TEMPERATURE VARIATIONS THROUGHOUT
MONTEREY BAY, SEPTEMBER 1971-OCTOBER 1972

David Howard Moomy

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Monterey, California

TEMPERATURE VARIATIONS
THROUGHOUT MONTEREY BAY
SEPTEMBER 1971-OCTOBER 1972

by

David Howard Moomy

Thesis Advisor:

D. F. Leipper

March 1973

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Temperature Variations Throughout Monterey Bay
September 1971-October 1972

by

David Howard Moorny

Lieutenant, United States Navy

B.A., University of Michigan, 1967

Submitted in partial fulfillment of the
requirements for the degree of

MASTER OF SCIENCE IN OCEANOGRAPHY

from the

NAVAL POSTGRADUATE SCHOOL
March 1973

Library

Naval Postgraduate School I

Monterey, California 93940

ABSTRACT

Temperature data was obtained at nine stations in Monterey Bay
on a weekly basis from September 1971 to October 1972. Monthly
mean depths of the isotherms were computed and compared to the
long term mean depths of these isotherms. Sea surface temperature
patterns and the topographies of the 10 C surface were drawn.
It was found that the period from October 1971 to May 1972 was
colder than normal while the months from June 1972 to October 1972
were warmer than usual. The NMFS coastal upwelling index was a
relative indicator of isotherm depth in relation to the long term
mean depths of these isotherms.

Quasi- synoptic observations between two offshore stations
indicated that the north- south component of the offshore current
seldom exceeded 20 cm/sec. The inferred flow from the surface
(T contours and the topographies of isothermal surfaces were
compared to current flow determined by drogue measurements. The
overall direction of the offshore current and the inferred flow in the
bay compared reasonably well to the proposed flow in the numerical
model of current patterns in the bay by Garcia [1971].

III.

TABLE OF CONTENTS

I. INTRODUCTION 9

A. GENERAL BACKGROUND 9

B. DESCRIPTION OF MONTEREY BAY 11

C. PREVIOUS RESEARCH 12

D. OBJECTIVES 15

II. PROCEDURE 17

A. DATA COLLECTION PROCEDURE 17

RESULTS 20

A. DESCRIPTION OF UPWELLING INDEX 20

B. THERMAL FLUCTUATIONS AT NINE BAY
STATIONS _ 21

1. Comparison of Depth of 10 C and 9°D Isotherms
to 40-Year Mean Depths at Station. 5 23

2. Comparison of Weekly Fluctuations to Monthly-
Mean 25

C. TWO STATION COMPARISON GRAPHS 27

1. Sea Surface Temperature Comparisons at
Stations 1 and 5 28

2. Sea Surface Temperature Comparisons at
Stations 4 and 8 30

3. Comparison of Depth of 9 C Isotherm at
Stations 4 and 8 31

D. THERMAL TOPOGRAPHIC CONTOUR CHARTS 32

1. Sea Surface Temperature 32

2. Mean Topography of 10 C Isotherm Surface 38

E. CURRENT PATTERNS IN MONTEREY BAY 42

1. Relation of Currents to Isothermal Surfaces 43

2. Relation of Drogue Tracks to Surface

Sigma- T Contours 46

F. OFFSHORE CURRENT 48

1. General Remarks 48

2. Synopsis of California Current 49

3. Synopsis of Davidson Current 50

4. Variations in the Flow of the Offshore Current 51

5. Current Profiles and Mass Transport from

Stations 2 and 3 52

6. Current Profiles from other Stations in and near
Monterey Bay 55

7. Relationship of Measured Offshore Current to
Events in Monterey Bay 55

G. TEMPERATURE-SALINITY CHANGES AT

STATIONS 2 AND 3 57

IV. CONCLUSIONS AND RECOMMENDATIONS 59

A. CONCLUSIONS 59

B. RECOMMENDATIONS 63

APPENDIX A_ 65

BIBLIOGRAPHY 156

INITIAL DISTRIBUTION LIST 158

FORM DD 1473 160

LIST OF FIGURES

1. Location of Monterey Bay Regions and Cruise

Stations 65

2. Location of Extended Bay Cruise Stations 66

3. Comparison of 1971-1972 Monthly Value of

Upwelling Index to the Long Term Mean Value 67

4. 1971-1972 Upwelling Index Anomaly Values 68

5-13. Isotherm Fluctuation at Stations 1 through 9 69-77

14. Comparison of Monthly Depths of the 9°C and
10°C Isotherms at Stations 5 to Long Term

Mean Depths 78

15. Comparison of 1971-1972 Sea Surface Temperature

at Station 5 to Long Term Mean Values 79

15A. Comparison of Upwelling Index Anomaly to the

Temperature Anomaly at Station 5 80

16. Weekly Fluctuations in the Depth of 10 C Isotherm

at Station 5 81

17. Comparison of Monthly Sea Surface Temperature
at Station 1 and Station 5 to Long Term Mean

Monthly Values 82

18. Comparison of Monthly Sea Surface Temperature
at Stations 4 and 8 to Long Term Mean Monthly

Values 83

19. Comparison of Monthly Depth of 9 C Isotherm at
Station 4 and Station 8 to Long Term Mean

Monthly Depths 84

20-33. Mean Sea Surface Temperatures September 1971-

October 1972 85-98

34-47. Mean Topography of 10°t Isotherm September 197 1 -

October 1972 99-112

48. Drogue Tracks for 20-21 June 1972 113

49. Drogue Tracks for 20-21 July 1972 114

50. Drogue Tracks for 3-4 August 1972 115

51. Drogue Tracks for 30-31 August 1972 116

52. Comparison of Inferred Flow from 10°C Monthly
Isothermal Surface to Drogue Paths on 20-21 June

1972 117

53. Comparison of Inferred Flow from lot Monthly
Isothermal Surface to Drogue Paths on

30-31 August 1972 118

54. Comparison of Inferred Flow from 12 C Daily
Isothermal Surface to Drogue Paths on

20-21 June 1972 , 119

55. Comparison of Inferred Flow from Mean
June Sea Surface Temperatures to Drogue

Paths of 20-21 June 1972 120

56. Comparison of Inferred Flow from Mean "
August Sea Surface Temperatures to Drogue

Paths of 30-31 August 1972 121

57. Comparison of Inferred Flow from Mean
September Sea Surface Temperatures to

Drogue Paths of 30-31 August 1972 122

58. Moss Landing Marine Laboratory and
Hopkins Marine Station Cruise Stations where

Samples were Collected 123

59. Comparison of Flow Inferred from Surface $\
Contours of 19-21 June to Drogue Paths on

20-21 June 1972 124

60. Comparison of Flow Inferred from Surface of (T±

28-30 August to Drogue Paths on 30-31 August 1972 125

61. Stations Where Geostrophic Current Information

was Available 126

61A. Mass Transport Between Stations 2 and 3 127

62_64. Geostrophic Current Profiles Between

Stations 2 and 3 128-130

65. . Geostrophic Current Profiles of 17 August 1972 131

66. Geostrophic Current Profiles from Pairs of

Stations Near Monterey Bay 132

67-78. Inferred Current Based on Surface Values of OT

September 1971-October 1972 133-144

79. Typical Monthly Temperature-Salinity Curves

at Station 2 145

80. Typical Monthly Temperature-Salinity Curves

at Station 3 146

81-94. Typical Temperature-Salinity Curves for

Stations 2 and 3 for September 1971-October 1972 147-154

95. Recommended Station for Addition of Bav Cruise .155

ACKNOWLEDGEMENT

The author wishes to thank Dr. Dale Leipper for his guidance
and encouragement in this project. Special thanks are due to Mr.
Jerrold Norton of the Department of Oceanography, Naval Postgraduate
School for his invaluable assistance in collecting and processing the
large amount of data taken during this study. Also, the author would
like to thank Mr. W. R. Reynolds, Master, R/V ACANIA and his
crew for their friendly assistance during the data collection phase of
this project. Finally, I would like to thank Professor R. Paquette
for altering his cruise plans so that several additional- bay cruises
could be conducted.

Finally, the author wishes to thank his wife, Barbara, for her
tremendous assistance in preparing the rough draft of this manuscript
and for preparing many of the drawings.

I. INTRODUCTION

A. GENERAL BACKGROUND

The Department of Oceanography of the Naval Postgraduate
School (NPS) commenced a sequence of studies of the thermal
structure of Monterey Bay in 1970. The first step in this project
was the work done by Lammars [1971] where he computed 40 -year
averages of the thermal characteristics from available data and
inferred currents in the bay from certain aspects of these temperatures
averages. Next, Anderson [1971] compared the thermal conditions
during short periods in 1966-1967 and 1970-1971 when quasi- synoptic
data -were available to the long term averages of Lammars. These
two investigators used data collected by other researchers. In the
fall of 1971 McClelland [1972] conducted a five month temperature
survey of Monterey Bay using a nine station grid, visiting these
stations on a weekly basis. The present author's study is a continua
tion of McClelland's -work and provides data to complete a consecutive
fourteen month study of the temperature structure of Monterey Bay.

The Monterey Bay area is one of the popular tourist attractions
along the central California coast. It is a region known for its clear
waters, aquatic sports and beautiful shoreline. A threat to these
attractions is the growing population in the communities around the

bay. This increased population demands more and more services
which are dependent to some extent on Monterey Bay. These services
incKide disposal of waste products, the elimination of heated water
from power stations and the need for oil and thus the need for ocean
going .tankers to provide the oil for local use. The bay has also been
an important location for the commercial fishing industry.

It is important to know the temperature averages or normal
thermal conditions for many reasons. For example it enables the
detection of changes caused by thermal pollution. Such pollution
could be caused by the introduction of relatively warm water into the
bay from power plants or other industrial activities. Changes in
thermal conditions could change chemical reaction rates or critically
affect the environment for certain species of marine life.

One of the factors influencing the location of sewage outfalls or
tanker anchorages is knowledge of v/hat will happen to pollutants
once they are deposited in the ocean. Will they be carried out to
sea and be dispersed to the point where they are no longer noticed
by man or harmful to marine life or will they end up concentrated
in a particular area or scattered along the beaches of Monterey Bay?
In order to determine which scenario will take place it is vital to
understand and be able to describe the current patterns in the bay
throughout the year.

10

It is hoped that the results of this work will be beneficial to
those interested in ocean related activities where current and
temperature information is necessary.

B. DESCRIPTION OF MONTEREY BAY

Monterey Bay is a nearly semi-eliptical indentation in the coast-
line of central California. The bay is approximately 20 miles from
north to south while the depth of indentation is about 10 miles. The
center of Monterey Bay is approximately 36 48 N and 121 54'W. The
seaward limit of the bay is a line running from Pt. Pinos to Pt.
Santa Cruz.

The bay can be divided into three main sections based on its
bottom topography. These sections are the southern and northern
shallows and the Monterey Submarine Canyon. The deep intrusion
of the Monterey Submarine Canyon into the bay effectively splits the
bay into halves. The southern shallows are south of the canyon and
include that region of the bay shoreward of the 100 meters isobath.
The northern shallows are north of the canyon and include that portion
of the bay shoreward of the 100 meters isobath. The bottoms in
these two regions of Monterey Bay are relatively flat. The Monterey
Submarine Canyon has very steep sides and reaches a depth in excess
of 2000 meters within 10 miles of the city of Monterey. The deepness
and orientation of the canyon allows deep oceanic water access to the
center of Monterey Bay.

11

C. PREVIOUS RESEARCH

The first long term oceanographic investigation of Monterey Bay-
was conducted by Skogsberg [1936]. He obtained oceanographic
observations over a five year period from 1929-1933. He had 23
stations located about the bay with 21 of these in water shallower
than 100 meters. The majority of these stations were in the southern
portion of the bay. Due to the limited seaworthiness of his ship he
was unable to visit these stations on a regular basis. Also Skogsberg
was not able to visit all of the stations on a given day. In certain
years only some lines of his stations were visited. Thus, while he
had a long term study he did not have continuous data from a series
of stations.

At his stations Skogsberg obtained temperature, salinity and
other chemical data and from this information he was able to divide
a year into three oceanographic seasons. These three seasons hav
come to be known as the Upwelling Period, the Oceanic Period and
the Davidson Current Period.

Bolin [1964] in his study of one station over the Monterey Sub-
marine Canyon for a five year period refined the definition of the
oceanographic seasons as proposed by Skogsberg as given below:

1. Upwelling Period - This period lasts from about mid-
January to sometime in September. During this time the
coastal water is ascending and the depth of various

12

isotherms become shallower. The isotherms reach their
shallowest depth in April or May and begin descending in

June. During this period the surface temperatures in the

o °

bay are in the 10 C to 1 1 C range.

2.. Oceanic Period - This period commences upon the comple-
tion of the Upwelling Period "ien the winds become weak
and intermittent. The Ccca:,, : Period usually lasts only
two months, September and October. It is generally
characterized by the sea surface temperature of the bay
being greater than 13 C and strong vertical temperature
gradient in the upper 100 meters.
3. Davidson Current Period - This period lasts from November
to mid- January, which is the period when the nearshore
counter current is flowing at the surface. This period can
be characterized by weak vertical temperature gradients
with the surface to 50 meter region well mixed. The
surface temperatures are usually lower than in the Oceanic
Period but not as low as those occurring during the Upwelling
Period.
These descriptions of the oceanographic seasons in Monterey Bay
should be considered only as general guidelines. The periods may
occur earlier or last longer than described above due to changes in
the driving forces which cause them. The features of these seasons

13

may be more intense or hardly distinguishable depending on the
generating forces during a given year.

Lammars [1971] used all available temperature data from a
40 year period to compute monthly averages of the horizontal and
vertical temperature distributions in Monterey Bay. He concluded
that progressive warming was occurring in the Bay and that the upper
layers of the Bay over the Monterey Submarine Canyon were warmer
than the shallow regions to the north and south. Lammars also
concluded that the topography of the 10 C or 11 C surface (depending
on the month) would be useful to infer current flow in Monterey Bay.

Anderson [1971] compared thermal conditions in Monterey Bay
from September 1966 to September 1967 and from January 1970 to
June 1971 to the monthly averages computed by Lammars. He
compared sea surface temperature, the temperature at the 20 meter
isobath and the depth of the 9 C and 10°C isotherms. He found that
1966- 1967 was approximately normal but that there was more intense
upwelling than normal in 1970-1971.

McClelland [1972] initiated the use of a nine station grid to cover
the various regions of Monterey Bay. His study covered the Oceanic
and Davidson Current Periods. He found that short term thermal
fluctuations were comparable to those found by other investigators
but that the seasonal changes in this period were more rapid than

14

previously noted. Also he computed the north- south component of
the gcostrophic currents between a pair of stations off Pt. Pinos.

D. OBJECTIVES

The objectives of this oceanographic study of Monterey Bay are:

1. To supplement the information obtained by McClelland [1972],
obtaining temperature data for a continuous fourteen month
period from a set of locations covering a substantial portion
of Monterey Bay.

2. To describe the various thermal fluctuations at this set of
stations in the bay and relate these fluctuations to the
oceanographic seasons described by Skogsberg [1936] and
Bolin [1964].

3. To compare monthly mean patterns of sea surface tem-
perature to those based upon the 40 year monthly means
computed by Lammars [1971] and attempt to explain any
anomalous results.

4. To compare monthly mean topographies of the 10 C surface
to those based upon the 40 year monthly means determined
by Lammars and attempt to explain any anomalous results.

5. To compare direct current measurements to currents
inferred from some easily obtainable parameters such as
the topography of a specific isothermal surface of (T

15

patterns in order to test the practicability of using such
a parameter to infer currents in Monterey Bay.

6. To describe inferred currents in the fourteen month period
if the above approach seems to give reasonable results.

7.. To compute the geostrophic north- south components of
the California or Davidson Current between two stations
located off of Pt. Pinos and to compute other components
between other pairs of stations located in or near Monterey
Bay.

8. To relate the computed north- south components of the

offshore currents to the inferred surface current patterns
in the bay.

16

II. PROCEDURE

A. DATA COLLECTION

The majority of the data used in this study was collected from
the Research Vessel ACANIA operated by the Oceanography Depart-
ment of the Naval Postgraduate School. A weekly cruise was conducted
■which covered a nine station grid of Monterey Bay. These stations
are numbered 1 through 9 in Figure 1. These nine stations were
chosen to provide stations which could all be reached within a 12 to
14 hour period and yet which would provide coverage of the various
features of Monterey Bay such as the southern and northern shallows,
the Monterey Submarine Canyon section, and to obtain the north-south
geostrophic component at two stations offshore. They were also
located close to stations where previous data had been obtained by
Skogsberg, Bolin and CALCOFI.

At each station a mechanical bathythermograph (MBT) was
lowered to obtain the temperature profile while surface temperature
was recorded using a bucket thermometer. At stations 2, 3, 4, 5 and
8 expendable bathythermographs (XBT) were also used to obtain a
temperature profile. Surface temperatures were also recorded
at mid-points between stations.

On most cruises Nansen casts were made at Stations 2 and 3
using 10 bottles at depths of 0, 20, 50, 100, 200, 300, 400, 600, 800

17

and 1000 meters. Temperatures were obtained from standard
reversing thermometers while salinity was determined using an
induction salinometer.

Supplementary data was obtained during several Extended Bay-
Cruises conducted by personnel of the Naval Postgraduate School
aboard oceanographic vessels (AGOR class) provided by the Naval
Oceanographic Office for short periods of time. This AGOR class of
vessel enabled a greater area to be surveyed due to its overnight
ability and its greater speed. The R/V ACANIA was limited at this
time to daily trips due to crew limitations and had a maximum cruising
speed of 10 knots.

The first Extended Bay Cruise was conducted on 8-10 May 1972.
Data was obtained at the regular nine stations in the Bay Cruise plus
data from the stations indicated by Roman numerals in Figure 2.
The second Extended Bay Cruise was held on 16-17 May 1972 and
data was collected from the nine stations of the weekly Bay Cruises
plus Station II. The third Extended Bay Cruise was conducted on
1-2 August 1972 where the regular bay cruise stations were visited
along with stations concerned with other oceanographic research.

Data collection procedures on these cruises were the same as
on the weekly bay cruises except that when an STD was available it
was used to supplement hydrographic data obtained by Nansen casts
and bathythermographs.

18

Skogsberg [1936]. McClelland [1972] and Broenkow [1972] reported
the presence of internal oscillations in Monterey Bay. The oscillations
occurred over a period of only hours, thus indicating non- steady
conditions in the bay. Broenkow [1972] at two stations near the head
of the canyon states that the oscillation of the isotherms and other
oceanographic parameters was related to the tidal cycle.

It was necessary to assume that each cruise provided synoptic
observations although it is obvious that large fluctuations in isotherm
depth and other parameters can occur within periods of only a few
hours. The time between first and last observations was 12 to 14
hours. This was the fastest coverage that could be obtained since
we were limited to the use of only one vessel, the R/V ACANIA.

The weekly bay cruise data in October was supplemented by
hydrographic observations made at CALCOFI station lines 67 and 70.
Thus geostrophic current information was available at stations near
Monterey Bay.

19

III. RESULTS

A. UPWELLING INDEX

The National Marine Fisheries (NMFS) and the Fleet Numerical
Weather Central in Monterey calculate a coastal upwelling index for
various locations along the coast of North America. The location
nearest Monterey Bay is at 36°N, 122°W which is approximately 40
miles to the south of the bay. These index values are computed from
the offshore component of the Ekman surface transport which is based
on monthly mean surface atmospheric pressure data. Bakun [in press]
has more detailed information on the procedure used to calculate the
coastal upwelling index.

The annual rhythm of the upwelling cycle at 36 N 122 W is
presented in Figure 3. The solid line indicates the 1971-1972 values,
while the dashed line represents the long term mean values based on
calculations from 1948 to 1967. From this graph, it can be seen that
upwelling occurs throughout the year though it is weak during the
late autumn and early winter months. The units of the upwelling
index are metric tons per second per kilometer of coast.

Figure 4 shows a plot of the upwelling index anomaly. This
anomaly is the difference between the monthly value of a given year
and the long term mean value for the same month. A positive

20

anomaly means that upwelling was more intense than normal while a
negative anomaly indicates the upwelling during that month was
weaker than the long term mean. During the fourteen months of
this oceanographic investigation, there was a positive anomaly for
only 4 months. There were 2 months where the monthly upwelling
index value and the long term mean were identical while there were
8 months when a negative anomaly existed.

B. THERMAL FLUCTUATIONS AT NINE BAY STATIONS

The average monthly depths of the isotherms at each of the nine
stations in the Monterey Bay Cruise station grid are shown in Figures
5 through 13. The monthly average depth at a station was determined
by summing the depths of the isotherms measured during a month of
the weekly cruises and dividing by the number of cruises made that
month at that station. The maximum depth at which temperature d? ta
was regularly obtained was 300 meters, the limiting depth of the
mechanical bathythermograph. Thus at the deep water stations,
Stations 2, 3, 4 and 5, the isotherm depths are shown for only the
upper 300 meters. At Stations 1, 6, 7, 8 and 9 the depth capability
of the bathythermograph was equal or greater than the water depth.
Therefore at these stations the isotherm depths are representative
of the entire water column.

In general the isotherm patterns during 1972-1973 agree with
the results obtained at a few of the same locations by Skogsberg [1936]

21

and Bolin [1964]. Their annual cycles showed the isotherms beginning
their ascent in January, reaching a peak in April or May and then
descending again til January. Their patterns also show an influx of
warm water during the months of August and September. Lammars
[1971] has plots of the Skogsberg and Bohn annual cycles.

While the overall pattern of the isotherm fluctuations at stations
■where comparisons could be made v/as similar to previous patterns,
there were several deviations from the normal. The first of these
features was the apparent surge of upwelling in December 1971 and
January 1972 which caused the. sea surface temperature and the
temperature of the upper layers at Stations 1, 2, 6, 7 and 9 to be

o Q

between 10 C and 11 C, about a degree lower than normal.

Another interesting event was the warming to 12 C seen in the
surface layers at Stations 3, 8 and 9 in the month of March. This
occurred at the offshore station (3) and the two stations near to
shore (8 and 9). The rest of the stations in the bay did not show this
warming.

By far the most interesting feature was the rapid warming in the
surface layers which occurred at all stations starting in June 1972.
The previous works by Skogsberg and Bolin show warming beginning

in June but only in the 12 C to 13 C range. In 1972 this warming

o o

caused temperatures in the 14 C to 15 C range to be present in these

layers at all stations in the bay. These warm pockets in late summer

22

have usually disappeared by October. In October 1972 the deepest
depths for the year for the 12°C - 15 C isotherms were measured
indicating the greatest warming. There was obviously some heating
process or weakening of upwelling taking place at this time.

Greater changes in depth of isotherms, particularly the 9°C
isotherm, occurred at Stations 2, 4 and 5 than at Station 3. Stations
2, 4 and 5 are located over the Monterey Submarine Canyon, but near
shore, while Station 3 is located 23 kilometers offshore. These
greater changes of isotherm depth could be indicative of upwelling
occurring more intensively at these coastal stations than in the
offshore region.

1. Comparison of Depth of 10 C and 9 C Isotherms to 40-Year
Mean Depths at Station 5

Figure 14 shows the comparison of the depths of the monthly

o o

average of the 9 C and 10 C isotherms from 1971-1972 to the 40 year

mean depth as computed by Lammars [1971]. The depths of the iso-
therms at Station 5 are compared to the depths computed at Lammars
block 3.

The depths of the 9 C and 10°C isotherms for 1971-72
correspond fairly well to the long term depths for the months of
September through November 1971. From December 1971 through
April 1972 the depths of the isotherms were less than the long term
mean indicating that the surface layers of the bay were colder than

23

normal for this period. During this time the upwelling index indicated
normal or stronger than normal upwelling except for the month of
February. This would tend to indicate shallower depths than normal
for the isotherms which is as observed.

Both the 9 C and 10 C isotherms reached their minimum
depths in April. These depths were approximately the same as

computed by Lammars but the peak in April for both isotherms

o
occurred one month early for the 9 C isotherm and two months early

for the 10 C isotherm.

During the period from May 1972 through October 1972, the

o °

depths of the 9 C and 10 C isotherms for 1971-1972 were greater than

the long term mean. There was an indication that the upper layers of
the bay were warmer than normal. The upwelling index for these
months had a negative anomaly indicating that upwelling was not as
strong as normal. Thus the combination of weak upwelling and heatir
and mixing from above tended to drive the isotherms deeper.

October 1972'at Station 5 shows a rapid deepening of all
isotherms indicating a period of weak upwelling. This was also the
month with the largest negative anomaly of the upwelling index.

There was evidence of the same type of cycle occurring at
other stations in the bay but Station 5 was used as an example because
Lammars had good data from that region and it is over the canyon so
there would be less influence of near-by landmass than at other
stations.

24

Figure 15 shows the relation between the sea surface tem-
perature (SST) for 1971-72 (solid line) at Station 5 and the long term
mean determined by Lammars for his similarly located Block 3.
It shows that when there was generally normal, or a positive anomaly,
to the upwelling index (October 1971-April 1972) the SST was lower
than normal. During the months when there was a negative anomaly
to the upwelling index (May 1972-October 1972, September 1971) the
SST at Station 5 was higher than the long term mean. Thus the anomaly
of the upwelling index appears to be generally related to the deviation of
the present sea surface temperature from the long term mean.

In Monterey Bay the upwelling index seems to be a good
indicator of general trends of isotherm movement, in relation to the
long term means. When there is a positive anomaly indicating more
intense upwelling than normal the isotherm depths were less than
the long term mean. When there is a negative anomaly the isotherms
■were deeper than normal.

A straight line was fitted to a plot of monthly upwelling index
anomaly versus the difference between the long term monthly mean
depth of the 10 C isotherm and the monthly depths for 1971-1972.
The slope of this line was +0. 54. This plot is shown in Figure 15 A.
2. Comparison of Weekly Fluctuations of the Isotherms to

their Monthly Mean Values

There was rapid change in the depths of the isotherms at all
stations throughout the period of this study. Figure 16 shows the

25

weekly fluctuations as a thin solid line and the average monthly depths

are connected by the heavier line. This figure shows the fluctuations

o

in the depth of the 10 C isotherm at Station 5. It was typical of the

fluctuations of other isotherms at other stations.

The weekly oscillations were generally greater than the
monthly changes in the average depth of a given isotherm. On occasion
these weekly changes were of the same order of magnitude as the
annual change in the monthly average depths.

The change in depth of an isotherm from one week to the
next could have been generated by one or several causes occurring
at the same time. The temperature data could have been obtained
during a different portion of the cycle of an internal wave, giving
different depths at different times for the same isotherm. An eddy
or a meander in the offshore current system could have been carried
a different water mass into the bay, again causing the change of
depths in the isotherms. The offshore current possibly switched
direction between observations, again changing the characteristics of
the waters of the bay.

About the only conclusion is that the waters of the bay -were
highly variable but that the monthly average depths of the isotherms
were a reasonable indicator of the overall condition of the bay. The
waters of the bay can apparently be disturbed quite easily; thus a
single observation would not be indicative of mean conditions of the
bay.

26

C. TWO STATION COMPARISON GRAPHS

Graphs of the type shown in Figures 17, 18 and 19 were used by
Anderson and McClelland to portray the comparative changes with
time in the sea surface temperature or depth of isotherms for a pair
of stations. Each point on the graph shows the monthly average sea
surface temperature or depth of an isotherm at both stations. The
horizontal temperature or depth gradient can be determined if the
distance between stations is known. Anderson plotted the 40 year
average data compiled by Lammars for Lammars' Blocks 1, 3 and 9.
Comparisons were done for Stations 4 and 8 and Stations 1 and 5
because these stations from the weekly bay cruise corresponded to
Lammars' blocks. The solid line connects the average monthly
values determined in 1971-1972 while the dashed line connects the
40-year monthly mean values.

From these graphs it can be seen which station changed tem-
perature or depth most rapidly and whether or not there was a
directional tendency. A positive 45 degree line implies an equal
change in temperature or depth in the same direction at both stations.
A more horizontal line segment indicates that the station represented
along the abscissa changed more rapidly than the station represented
along the ordinate.

If the monthly value of sea surface temperatures at both stations
were lower than the long term mean values , then the 1971-1972

27

monthly value will be to the left of and lower than the long term
mean value.

1, Sea Surface Temperature Comparison at Stations 1 and 5

Figure 17 compares the average monthly values of sea
surface temperature at a mid-canyon station, Station 5, and a
southern shallows station, Station 1. These two stations compare
changes in a north-south direction. The first thing that is obvious
was that there was basically two distinct periods. The first of these
periods was from October 1971 through May 1972 when the sea
surface temperature at both stations was lower than the 40 year means
for the appropriate months. The second period consists of the months
of June 1972 through October 1972 when the sea surface temperature
was higher at both stations than shown by the 40-year mean values
for the appropriate months.

The first period described above was also the months when
there was a positive anomaly in the NMFS upwelling index. Thus it
appears that when there was more intense upwelling than normal
taking place, the sea surface temperature was lower than indicated
by the 40-year mean value of the sea surface temperature. The
second period outlined above was the months when upwelling was
weaker than normal. Thus it seems that the sea surface temperature
was higher than normal during these months of weak upwelling.

For all fourteen months of this study both stations were
either significantly higher or lower than normal. Thus what ever was

28

causing changes at one station was also affecting the other station
in the same manner though the magnitude of change was not the same
at both stations.

Both stations were higher than normal in September 1971.
The bay then rapidly cooled until December 1971 with both stations
cooling at approximately the same rate. Both stations warmed
slightly in January 1972 and February 1972. During March, Station 1
warmed a small amount (about 0. 3 C) while Station 5 cooled slightly.
Through April and May both stations again cooled. In June there was
a large amount of warming at the pair of stations. This warming
trend continued on through July 1972. August saw a cooling of the
waters at Station 1 while the temperature remained almost constant
at Station 5. In September, basically the opposite situation occurred,
Station 1 remaining constant and Station 5 cooling. There was a
significant warming at both stations in October 1972.

The largest change from one month to the next occurred
between May and June and this happened at both stations. Thus there
was a significant change in the waters at these two stations between
these two months. The least monthly change at both stations took
place between the months of December 1971 and January 1972 indicat-
ing that the water temperature at these two stations was relatively
stable during these months.

29

2. Sea Surface Temperature Comparison at Stations 4 and 8

Figure 18 compares the sea surface temperature at Station
4 and Station 8, which form an east-west pair. Station 4 was located
over a deep portion of the Monterey Submarine Canyon and near the
open ocean while Station 8 is situated at the head of the canyon in
shallower water and near the shore. Again there were two distinct
periods. The first period covered the months of October 1971 through
May 1972 when the sea surface temperature at both stations was lower
than the sea surface temperature indicated for the appropriate months
on the long term mean graph computed by Lammars. The month of
April at Station 1 was the only exception to this feature. These
months again are the months of average, or stronger than average
upwelling. The second period consists of the months of July 1972
through October 1972. During these months the sea surface tem-
perature at both stations was higher than normal.

The waters at Stations 4 and 8 were warmer thar normal
in September 1971. Both stations cooled rapidly at about the sam
rate from October through December 1971. Both stations warmed
slightly in January 1972 and February. In March Station 4 cooled
while Station 8 warmed. Station 4 warmed at about the same rate
that Station 8 cooled in April. In May both stations cooled, this
possibly was due to upwelling. June showed a rapid warming at both
stations and more or less a transition month between the two periods

30

described above. The water at both stations warmed rapidly in July.
Station 4 remained approximately constant through August while
Station 8 cooled slightly. September 1972 was almost identical to
August at both Stations 4 and 8 indicating that no change took place in
the bay at that time. October 1972 exhibited rapid warming at both
stations.

The most rapid cooling at Stations 4 and 8 took place between
September 1971 and October 1971. The greatest monthly increase of
sea surface temperature took place between May and June at Station 4
and June and July at Station 8. The least monthly change occurred
between August and September 1972 when both months were almost
identical.

3. Comparison of Depths of the 9 C Isotherm at Stations 4 and 8

Figure 19 shows the relationship between the depths of the
9 C isotherm at Stations 4 and 8. The depths of the isotherm at both
stations seems to fluctuate in a random manner from September 1971
to January 1972. Greater fluctuations in depth took place at Station 8
which is at the head of the Monterey Submarine Canyon. This could
be due to the magnified surge of the internal waves at this location as
described by McClelland [1972].

From January 1972 through April 1972 there was a decrease
in the depth of the 9 C isotherm at both stations. This was also the
only period in 1972 when normal or more intense upwelling was

31

denoted by the upwelling index. These two actions correspond
nicely, stronger upwelling indicating a raising of isotherms. The
period from June 1972 through August 1972 showed an increase in
the depth of the isotherms at both stations. This was also a period of
weaker than normal upwelling as depicted by the NMFS upwelling
index. Though upwelling was occurring during these months, it
appears that it was not strong enough to support the isotherms against
the heating and mixing occurring in the surface layers.

D. THERMAL TOPOGRAPHIC CONTOUR CHARTS
1. Sea Surface Temperature

Figures 20 through 33 show the contours of sea surface
temperatures over Monterey Bay for the fourteen months that were

covered in this oceanographic investigation. The isotherms were

o

drawn at 0. 2 C intervals and relative cold regions were marked

with a C while relative warm regions were marked with a W. The
monthly averages were computed at each station and at each mid-point
between stations using the sea surface temperatures from the weekly
bay cruises. Thus, on the average, 3 or 4 weekly values were used
to obtain each monthly average.

The chart from September 1971 was drawn using values
obtained during the cruises of 21, 22, 23 and 28 September 1971.
Thus it is probably more representative of the last 10 or 12 days of

32

the month than of the entire month. This chart .shows a tongue of
relatively cold water which more or less follows the axis of the
Monterey Submarine Canyon. This band of cool water was between
the warmer waters further offshore and the warm waters found near
the shore.

During October the average bay temperature was generally
2 C lower than at the end of September. This relationship seemed
to hold true at almost all stations, thus indicating that the bay cooled
uniformly during this time. Again there was a cool band of water
over the canyon axis with the region between the mid-point of Stations 1
and ?. and Station 2 being the coldest point on the bay. There was also
warmer water both offshore and very near shore particularly in the
southern shallows. There was a resurgence of upwelling in October
which could have been the cause of the rapid uniform cooling of the
bay.

From October to November the surface water of the bay

o o

cooled slightly (about 1 C), but was more uniform with 12. 3 C beir _,

the most common temperature. The horizontal temperature gradients

were much weaker in November than in October. There was still a

large pool of cold water over the canyon but the marked increase in

sea surface temperature towards the open sea and the near shore

regions was absent. The general pattern present in September and

October was a tongue of cool water entering the bay from the south

33

near Station 2. In November this tongue-like intrusion had disappeared
and the isotherms took a roughly circular appearance.

The sea surface temperatures for December were lower
than those for November. Again there was a rotighly circular shape
to the contours and a cold spot generally centered over the axis of
the Monterey Submarine Canyon.

The month of January showed a slight warming over the
month of December. Again there was a large pool of cool water over
the canyon as in the previous month but it had expanded into the
southern shallows region. The range of temperature was quite
small being only 0. 6 C. The chart for February shows a cold tongue
of water centered at Station 6 and having a northeast- southwest trend.

There is also a cold tongue centered on Station 2 and extending into

o

the bay. The range of temperature was 0.9 C with the lowest value

on the outer edge of the southern shallows and the warmest area near
the shore in the southern shallows. Generally, waters were colder
in the center of the bay and warmer both further offshore and very
near the shore. This could be indicative of the location of upwelling
occurring in the bay. Horizontal temperature gradients were

generally weak.

o
In March the cold tongue at Station 2 had become 0. 2 C

colder and had spread out over the mouth of the bay. The horizontal

temperature gradients were stronger because the offshore and near shore

34

regions had warmed while the center had been cooled. The variation
between the warmest and coldest water had increased to 1. 9 C. The
upwelling index for March showed a marked increase in the magnitude
of upwelling, thus the cool tongue is probably due to the increase of
upwelling.

The April sea surface chart shows that the cold tongue from
the south had pushed farther into the bay causing the central part of

the Monterey Submarine Canyon and region near Station 6 to be 0.2 C

o

to 0.4 C colder than in March. The horizontal temperature gradients

were weaker due to colder water being present near the shore and the
extreme southern shallows.

With exception of the offshore station, Station 3, the entire
bay for the month of May exhibited the lowest sea surface temperatures

recorded for the period of this study. The cold tongue had intensified,

o
being 0. 6 C colder than in April. The horizontal temperature grad-
ients were stronger. It appears from this chart that upwelling had
intensified and was taking place over the canyon region of the bay or
that upwelled water was moving in from the south. There was a warm
tongue pushing out from the head of the canyon near Station 8 which
could possibly have been due to warm river runoff. There were again
low temperatures in the center of the bay with high temperatures near
shore and offshore.

35

The June chart shows a very different pattern than that
shown in May. Instead of the usual cold tongue from the south, there
is a very warm tongue pushing into the bay from the south. In general
the sea surface temperatures for June are 2 or 3 degrees warmer
than in May. There appears to have been a cold region located in the
northern shallows and in the southern shallows near Station 9. From
this chart it appears that upwelling was no longer dominating the bay
and that some other feature had taken over. This was anomalous to
the upwelling index which showed the strongest upwelling of the year
though it was less than the long term average.

July showed a general warming for the bay over the previous
month. There was a relative cold region located between Stations 2
and 3 which pushed its way into the southern shallows. There was a
large increase in temperature as one moved shoreward of Station 2
with a warin region generated in the extreme southern shallows.
There was a very strong horizontal temperature gradient ■''n these
areas. Possibly the upwelled water had been pushed to the southw st.

The monthly averages for August were slightly lower than
the J\ily values. There was a pool of cool water located in the vicinity
of Stations 2 and 4. From this region there was a strong increase in
sea surface temperature as one moved shoreward. There was a
strange feature at Station 5 where there was an intrusion of a warm
tongue of water. There was a strong horizontal temperature gradient
present in the bay during August.

36

The region of cold water present in August had contracted
by September but did not significantly change temperature. The
offshore waters had warmed while the near shore waters had cooled.
The warm intrusion at Station 5 which appeared in August had dis-
appeared by September. The horizontal temperature gradients were
weaker than in August, particularly in the southern shallows.

October was a very anomalous month. It is usually cooler
than August but this particular month the-, sea surface temperatures
were much higher. There was a cold region with its center in the
southern shallows which expanded out over the Monterey Submarine
Canyon. An interesting feature is that the southern shallows remained
at the same temperature as in September. Thus the greatest increase
in sea surface temperature occurred over the canyon and in the off-
shore areas. The relative cold tongue in October was a relative
warm region in September. There was also a warm area entering the
Monterey Bay region between Stations 2 and 3.

Generally there was a cool region over the Monterey Sub-
marine Canyon with the waters becoming warmer offshore and near
the shore.

The two months that overlapped in this study were September
and October. A comparison of the sea surface temperature for

September 1971 and 1972 showed that the bay was warmer in 1971

o
by about 1 C. The general trend of the contours was the same with

37

a region of cool water over the axis of the canyon and warmer water
at Station 3 and in the southern shallows. A comparison of the October
1971 and 1972 charts showed that 1972 was approximately 2. 0°C
warmer than 1971. October 1971 showed a region of cool water over
the axis of the canyon with the general direction of the isotherms
oriented north-south. The chart for 1972 shows a region of cool
water over the canyon and the southern shallows with the isotherms
generally running east-west.

This brief comparison showed that the same two months a
year apart arc very different from each other. This difference was
shown in the sea surface temperatures and in the general orientation
of the temperature contours.

2. Mean Topography of 10 C Isothermal Surface

The topography of the 10 C isotherm was chosen because it
probably best described the characteristics of the mid-waters (40-100
meters). The mid-waters were selected because it is at these depths
that the largest changes occur. This isotherm was also observed at.

most stations during the fourteen months of this study. The mean

o

topographies of the 10 C isothermal surfaces for the months of

September 1971 through October 1972 are plotted in Figure 34
through 47. The larger number indicates a greater depth of the
isotherm and the contours are drawn in 10 meter intervals. A "W"
indicates an area where the depth of the isotherm was deeper in

38

relation to the rest of the region and thus there was a thicker layer
of warm water above this depth. A "C" indicates a region where the
isotherm was closer to the surface in relation to other areas and thus
an area where the layer of warm water above this point was thinner.

September 1971 exhibited a cold core of water located at the

o

mid-point between Stations 2 and 3. The 10 C isotherm was very

near the surface during this month at this point. The range of depths
for this isotherm for September was 95 meters.

October 1971 shows a warm intrusion over the canyon from
both directions, the ocean side and the head of the canyon. The north-
ern and southern shallows were regions of cold. It appears the cold
water in the canyon flowed up the sides of the canyon and seeped along
or near the bottom to the shallow regions. The range of depths
recorded in October for the 10 C isotherm was 82 meters.

November 1971 again shows the depth of the 10 C isothern
to be greater over the canyon than over the shallow portions of the
bay. This would again indicate a flowing of water up and over the
sides of the canyon and into the shallow regions. The range of depths

of the 10 C isotherm was about 100 meters.

o
December 1971 also had greater depths for the 10 C isotherm

over the canyon than in shallow regions. There was an anomalous

cold spot between Stations 2 and 3 which could have been a small

localized region of upwelled v/ater. The range in this month was 75

meters for the isotherm.

39

January 1972 still had warmer water over the canyon to

greater depths than over the shallow sections of the bay. The small

o
localized shallow portion of the 10 C isotherm between Stations 2

and 3 was again evident in January. The range of the depths for the

10 C isotherm was 73 meters.

February 1972 had a warm water mass over the canyon

o

with depth of the 10 C isotherm becoming shallower as one came

nearer to the shore. The range of the depths recorded for the 10 C
isotherm in February was 53 meters. This was a considerably
smaller range than previously recorded and could have been due to
the onset of upwelling. The upwelling would tend to decrease the
depth of the 10 C isotherm particularly over the canyon where
upwelling was strongest and this would tend to decrease the range of
recorded depths.

March 1972 showed a general decrease in depth of the
isotherm from Station 3 towards the coastline. The range of depths
was 62 meters.

April 1972 had the least interesting of the monthly patterns.
The isotherm was slightly deeper offshore than over the inner portion
of the bay. The range was considerably smaller than previously
recorded, being only 34 meters. This -was the month that the iso-
therms reached their shallowest depth and the depth in deep water
was about the same as in shallow water. Thus there was no indication

40

of thi: seeping of water of this temperature up the sides of the canyon
and into the shallow regions of the bay.

May again has a warm layer indicated over the Monterey
Submarine Canyon. The range of depths was small, 33 meters, this
being a month of strong upwelling.

June 1971 was a month with a weak data base. The topography

o
of the 10 C isotherm shows a warm region over the canyon. The

range of depths was 40 meters, slightly larger than April and May

but still relatively uniform throughout the bay.

July was an uninteresting month and again there was only a

o

small change, 30 meters, in the depth of the 10 C isotherm during

this month of still strong upwelling.

Atigust had a warm tongue over the canyon with the depth of

o

the 10 C isotherm becoming shallower in the shallow portions of

Monterey Bay. The range of depths was again minimal, 30 meters.

September 1972 had a warm patch of water located at
Station 5 over the axis of the Monterey Submarine Canyon. The depth
of the isotherm rapidly lessens in the shallower portions of the bay.
The upwelling index shows a marked drop in the intensity of upwelling
for September and there was a significant change in the range of the
depth of the 10 C isotherm, being 70 meters for this month.

October 1972 shows a reverse pattern than had been seen

o

in previous months. The greatest depth of the 10 C isotherm

41

occurred at Station 8 at the head of the canyon with the depth of the
isotherm becoming shallower further seaward along the axis of the
canyon. This v/as again a month of weak upwelling and the range of
depths recorded for the isotherm was about 70 meters.

Diiring the months of relatively weak upwelling, September

through March, there were strong horizontal and vertical gradients

o

of the depth of the 10 C isotherm. The depths were greatest over

the canyon and closest to the surface in the northern and southern
shallows regions. This could have possibly been due to the water
flowing up the sides of the canyon and then seeping along or near the
bottom into the shallow regions. The range of the depths recorded
during this period was 70 to 100 meters in a given month.

The months of April through August were months of relatively
strong upwelling and during these months there was only a weak
horizontal and vertical gradient of the depth of the 10 C isotherm.
A commonly monthly range during these months was about 3^ meters

Generally there 'was a warm layer of water located over the

o

axis of the Monterey Submarine Canyon. The depth to the 10 C

isotherm decreased as the depth became shallower.

E. CURRENT PATTERNS IN MONTEREY BAY

An objective of this study ■was to attempt to find an easily obtain-
able parameter which could be used to describe the general surface
current patterns in Monterey Bay. In order to check the usefulness

42

of the various selected parameters, the results obtained from them
were compared to direct current measurements. Parachute drogues
were used to determine directly the current speed and direction during
a portion of the oceanographic investigation of Monterey Bay prepared
for the Association of Monterey Bay Area Governments (AMBAG) by
Oceanographic Services, Inc. In a few selected situations, these
drogue studies provided the type of direct current measurements
desired.

Four drogue studies were conducted between June 1972 and
August 1972 and the paths of the drogues are shown in Figures 48
through 51. These studies consisted of placing a number of parachute
drogues in a line generally running north -south and then tracking them
over approximately 24 hours. The drogties were rigged so that the
parachutes would deploy at a depth of 10 meters. With the parachutes
at this shallow depth, the drogue movements were probably indicative
of the surface currents in the bay. These drogues were either tracked
from a radar system located at the Naval Postgraduate School accord-
ing to the procedures outlined by Stoddard [1971] or they were tracked
using a ship and standard navigational procedures.

1. Relation of currents to Isothermal Surfaces

Leipper [1970] showed that temperature data alone could be
used to approximate the major currents in the Gulf of Mexico when
there were few direct current measurements available and there was

43

insufficient data for the geostrophic computations. Data collected on

several cruises there during the period 1965-1966 were compiled to

o

plot topographies of the 22 C isothermal surface. It was found that,

as would be expected under the geostrophic assumptions, the current
generally followed the contours with the greater depths of the iso-
thermal surface being on the right-hand side of the current as the
observer faces downstream.

Lammars [1971] investigated the feasibility of relating mean
currents in Monterey Bay to mean isothermal surfaces in a manner

similar to that employed by Leipper. Lammars used the topographies

o °

of the 10 C or 11 C surface in his investigation because he believed

that these surfaces provided the mean isothermal surfaces most
likely to be related to changes in the mean current. At a few times
when observations were available, he compared direct current
measurements taken on a given day in a given month to the topography
of the 40-year mean of the appropriate isothermal surface for that
month. He found a general agreement between the inferred flow and
the few available direct measurements of the currents.

It was hoped that currents could be inferred as outlined above
from the data obtained during the weekly bay cruises conducted for
the present study of Monterey Bay. When the currents inferred from
the topographies of various isothermal surfaces were compared to the
few available drogue paths it was found that there seemed to be no

44

good correlation. An example of this was the comparison of inferred
currents to drogues tracked on 20-21 June 1972.

Figures 52 through 54 show the topographies of various
isothermal surfaces and the drogue tracks for 20-21 June 1972 and
30-31 August 1972. The isothermal surfaces are plotted in 10 meter
intervals. The drogues are numbered and the initial position of each
drogue is marked with an S while the final position recorded for each

drogue is marked with an E. The various topographies plotted were

o o o o

the monthly means for the 9 C, 10 C, 11 C and 12 C isothermal

surfaces and the values for these same isotherms on a few selected
single days. When these drogue paths were compared to the inferred
currents as determined by the 40-year mean isothermal surfaces
computed by Lammars, there was again no good correlation between
inferred current paths and direct current paths.

The drogue paths were also compared to the sea surface
temperature contours, both monthly averages and those obtained the
day nearest to the day of the drogue study. There was good correlat >n
between drogue tracks and sea surface temperature contours for the
drogue study of 20-21 June. Figure 55 shows that drogues numbered
2 through 6 had moved in the same direction as the current inferred
from the temperature contours. There was excellent correlation
between the drogues paths of 30-31 August and the mean monthly sea
surface temperature contours for both August and September. This
is shown in Figures 56 and 57.

45

As can be seen in these few cases, the best correlation was
between the flow inferred from the SST pattern and the direct measure-
ment of the current. The drogues show a current which is going to
the east or northeast. When mid-depth isotherms were used the
inferr-ed flow shows the current with a generally southerly flow or to
the southwest. The comparison of flow inferred from mid-depth iso-
therms to that measured directly by drogues in June, July and August
1972 showed no correlation.

One reason why the mid-depth isotherm approach may not
always be used is that, because of large salinity variations, the topo-
graphy of an isothermal surface may not be an indicator of the density
structure upon which this method is predicated. Another reason why
this approach may fail at times is that the flow may not be always
geostrophic. These Monterey Bay surface currents are generally-
weak and could be easily perturbed by local winds, bottom topography
or tidal forces. Also, sudden changes may possibly be brought about
by changes in offshore meanders or eddies.

2. Relation of Drogue Tracks to Surface Sigma- T Contours

The next parameter to be investigated was the surface value
of 0~ . The salinity data used in this study was obtained from Moss
Landing Marine Laboratory (MLML) and Hopkins Marine Station (HMS).
This data was particularly appropriate since it was collected on the
same day or within one or two days of the AMBAG drogue studies.

46

Figure 58 shows the location of stations where surface « j.
values were available. All stations were not visited on the same day
but were sampled on consecutive days. Moss Landing's stations are
marked with an open circle while Hopkins' stations are located with a
cross. Contours of surface values were plotted using an interval of
0. 1 units. Drogue tracks are marked as before.

The comparison of surface (T values to the drogue tracks
is shown in Figures 59 and 60. The direction of the flow of the inferred
current would have the higher value of 0~ on the observers left-hand
side when facing downstream. This is assuming that the flow is geo-
strophic and that surface is indicative of density distribution. The

flow as inferred from the (T values and the flow indicated by the

t '

drogues are generally in the same direction, both show flow to the
northeast.

Figure 60 shows the drogue tracks and surface contours for
30-31 August. This study is particularly useful because"there are
drogue tracks in both the northern and southern shallows of Monterey
Bay. There is excellent agreement between the current as indicated
by the drogues and the current as inferred from the surface <T"
values. Both currents show flow entering the bay in the southern
shallows and leaving the bay in the northern shallows.

The results obtained by comparing direct current measure-
ments to current flow inferred from contours of surface <T" are

47

encouraging and tend to support the use of such an inference at times
to obtain the general direction of surface currents in Monterey Bay.

F. OFFSHORE CURRENTS

1. General Comments on the Offshore Current

An objective of this research was to examine the north- south
component of the geostrophic current near the southern entrance of
Monterey Bay. The majority of the data was obtained at Stations 2 and
3 from the weekly Monterey Bay cruises. Data -was collected at these
stations by means of Nansen casts to 1000 meters during the weekly
cruises while a self-contained STD was used during the Extended
Bay Cruises. Data at Extended Bay cruise stations III and II were
available for May 1972. Another series of cruises was conducted
in October 1972 using an STD system to record temperature, salinity
and depth at the Bay Stations and some CALCOFTStations which were
in or near Monterey Bay. These casts only 'went to a depth of 600
meters. All pairs of stations where offshore current data was avail
able can be seen in Figure 61.

The initial plan for this study involved the use of an STD so
that salinity, temperature and depth data would be available on a
weekly basis for all stations in the bay. This would have given the
density structure of Monterey and from this it was hoped that geo-
strophic currents could be inferred. However, the STD was lost

48

at sea during one of the extended Bay cruises. Funds were not avail-
able to replace this expensive instrument and thus most of the data
obtained during the year was temperature data only.

The Naval Postgraduate School IBM 360 computer system
wasthenused with a modified NPS Department of Oceanography
geostrophic program to process the data. This program made the
dynamic calculations necessary to give the geostrophic current
velocities at standard depths using a reference level of 1000 meters.
When the cast depth was less than 1000 meters at either station or
both stations, the computer was programmed to use the deepest
standard depth reached at both stations as the reference level. The
program also plots a profile of the current velocity components and
provides mass transport data.

The north-south current velocity components observed at
Stations II and III are plotted as a function of depth in Figures 62
through 64. Portions of the curves appearing to the right of the
ordinate indicate a northward flowing current. Depths are in meters,
and velocities are in centimeters per second.
2. Synopsis of California Current

The California Current is a southeastward flowing current
located off the west coast of North America. Wooster and Reid [1963]
indicate that the California Current is the eastern boundary current
in the clockwise circulation pattern of the North Pacific Ocean.

49

This current extends approximately 500 miles from the coastline and
flows at speeds generally less than 0. 5 knot. Since it is an extension
of the Aleutian Current, it carries the cold waters of the Gulf of
Alaska to the south. This water is warmed as it proceeds to the
south due to the effects of mixing with warmer waters and the effects
of solar insolation according to Reid, Roden and Wylie [1958].

Jennings and Schwartzlose [i960] used drogues with the
parachutes set at 10 meters to investigate the California Current in
March 195 8. They found that the current was flowing to the south-
east with an approximate speed of 0. 5 knot. Crowe and Schwartzlose
[1972] have shown that drift bottles released to the north of Monterey
Bay during the summe r months will drift into Monterey Bay or to the
coastline south of the bay, thus indicating a southerly flow off the
central California coast during these months.
3. Synopsis of Davidson Current

The Davidson Current is the name given to the northward
flowing countercurrent which is inshore of the California Current.
Sverdrup, Johnson and Fleming [1942] state that this countercurrent
is present throughout the year at a depth below 200 meters and that it
becomes a surface feature only in the late fall and winter when up-
welling has ceased. Anderson [1971] has brief descriptions of the
various proposed theories as to why the Davidson Current exists.

50

Reid [1962] used parachute drogues to measure the flow at
250 meters in the Davidson Current during November 1 96 1 . He found
a northward flow in a 40 mile wide section near the coast with a
maximum speed of about 0.5 knot. Crowe and Schwartzlose [1972] in
their compilation of 10 years of drift bottle data show that only those
bottles released near the coast are recovered. This would correspond
to Reid's observation that the Davidson Current is narrow and inshore
of the California Current. Reid and Schwartzlose [1962] used both
parachute drogues and geostrophic calculations to measure the
Davidson Current and found that the two methods compared favorably.
4. Variations in the Flow of the Offshore Currents

The California and Davidson Currents are generally weak
currents with their maximum speed less than 0. 5 knot. Since these
current systems are 'weak, they are easily perturbed and the overall
trend of the currents near the coast may be masked by stronger bui
short term currents induced by outside forces such as string local
winds, eddies or meanders in the current system, or tidal influenc s.

Eddy flow may be the main feature at work which masks the
overall current movement. Reid, Roden and Wylie [1958] state that
some disturbances in current flow are found on the inshore side of
the current. Evidence of eddy flow has been seen in a number of past
studies. Reid [1962] found eddy motion in his drogue study of the
Davidson Current off the coast of central California in 196 1. His

51

offshore drogues showed a clockwise eddy present with a portion of
the drogues greater than 40 miles offshore going to the south while
some even further seaward were tracked moving to the north.

The 1950-1964 mean monthly charts of the geostrophic
flow at the surface and 200 meters as presented in CALCOFI Atlas
Number 4 show an eddy to be present during most months near the
central California coast and Monterey Bay. These eddies were
present either when the California or Davidson C\irrent was the
predominate current system off the. mouth of the bay.

The flow in the offshore current has some effect on the
waters of Monterey Bay. This was shown in the results of drift
bottle studies conducted by CALCOFI from 1955 to 1971 and
presented in CALCOFI Atlas Number 16. This report revealed
that drift bottles released near shore and north of Monterey Bay
end up on the beaches surrounding the bay when the California
Current was the dominate current. Bottles released near shore and
south of Monterey Bay during the Davidson Current period also end
up on the shores of the bay. These offshore currents apparently
transfer the drift bottles to the current patterns in the bay.

5. Current Profiles and Mass Transport for Stations 2 and 3

There were 42 cruises during the fourteen months of this
oceanographic investigation for which the north-south component of
the geostrophic current and mass transport were computed. The

52

individual profiles are shown in Figures 62 through 64 while a graph
of mass transport is shown in Figure 62A.

The mass transport graph shows the direction of the overall
flow from a given profile. An individual profile may have two or
three current layers but the mass transport will present the direction
of the net flow.

From the months of September 1971 through May 1972,
seventeen measurements of the mass transport indicated a northward
flow while nine measurements depicted a southward flow between these
two stations. It appears that the Davidson Current in this observed
period commenced two months earlier than normal and possibly
lasted fotir months longer than its normal cut-off month of January.
The direction of the current seemed to change directions every few
weeks and maintained the new direction for several weeks. The
period from June 1972 through October 1972 showed a very dominant
southerly flow.

The current profiles generally showed that the maximum
current velocity was found in the upper 100 meters and that the
maximum speed was usually less than 20 centimeters per second
though there -were several instances where the maximum current
speed was as much as 40 centimeters per second.

There were several interesting features noted in some of
the current profiles. There was a large acceleration in current flow

53

between the data collected on 8 and 9 May 1972. This rapid change
could have been caused by an intensification of local winds or a
movement of the faster offshore current shoreward. The current had
changed direction by 16 May. There was a marked decrease in the
current speed between 16 and 17 May. This change could have been
caused by strong northerly winds offsetting the flow of the northward
flowing current of the passage of an eddy.

During the cruise of 17 August a special stop was made at
the mid-point between Stations 2 and 3 and a Nansen cast was taken.
The current between Stations 2 and 2 showed a predominantly south-
ward flow with its maximum speed of 7 centimeters per second at
250 meters. The current profile between Stations 2 and 3 indicated
a northward flowing current with a maximum speed of 27 centimeters
per second found at the surface. The normal current profile for
Stations 2 and 3 had a northerly current from the surface to about
250 meters with its maximum speed of 15 centimeters per second a
the surface. Below 250 meters there was a very weak southerly
flow. These three profiles can be seen in Figure 65.

The north-south components of the geostrophic current
computed from 24 August to 14 October indicated relatively strong
southward flowing currents. A distinctive feature of this period was
a pulsating rhythm. One week the current is relatively fast and the
next week it had slowed down considerably and the following week

54

its speed had increased again. Also from 29 August through 21 Sept-
ember there was a core of high current speed at a depth of 100 to
150 meters. On 2 October 1972 and 14 October 1972 this core of
high current had shifted to a depth of 200 to 250 meters.

6. Current Profiles from Other Stations in and near
Monterey Bay

A limited amount of data was available to compute the north-
south component of the offshore geostrophic c\irrent. This data was
available for Stations II and III of the Extended Bay Cruise of 8-10
May 1972 and at CALCOFI Stations 67-50, 67-55, and 67-60 and
Stations 70-55 and 70-60 for two cruises in October 1972. Since
this data was of such a limited nature it was not useful in this work
but is presented in Figure 66 for future work.

7. Relation of Offshore Current to Current Patterns in
Monterey Bay

Garcia [1971] developed a numerical model of the current
patterns in Monterey Bay. He found that a closed gyre could be
established in the bay. In order to determine the validity of such a
model it is necessary to check it against field measurements of the
currents. In paragraph III-E-2 it was shown that there was reasonable
correlation between drogue paths and the current direction inferred
from surface sigma-t values. Assuming that surface sigma-t
contours can be used in all months to infer current patterns, it

55

would be interesting to compare the currents inferred from these
contours to the current patterns predicted by the numerical model

Current flow in the bay in the model depends on the direction
of the offshore current. The offshore current drives the bay currents
by means of a shear stress mechanism. A southward flowing off-
shore current would cause a counterclockwise gyre while a northward
flowing offshore current would cause a clockwise gyre.

Figures 67 through 78 show the inferred currents based on
the available surface sigma-t contours. The geostrophic current
profile computed between Stations 2 and 3 is shown on the left-hand
side of the figure. There were twelve periods when data was avail-
able to plot contours of surface sigma-t and nine periods when the
data of the computation of the offshore geostrophic current was close
to date when sigma-t data was collected.

For eight of the twelve periods the relationship between the
direction of the offshore current and the inferred current flow in the
bay were in agreement with Garcia's model. The months of December
1971 and June 1972 could not be compared because the difference in
time of the two data collection period. November 1972 was not
compared because no general trend could be found in the current
patterns in the bay. The month of March 1972 was the only month
when the direction of flow in the gyre predicted by the model and the

56

inferred flow did not correspond. This could have possibly been
caused by a meander of the offshore current system bending into
Monterey Bay.

It appears that the direction of the gyre in the bay predicted
by Garcia's numerical model conforms to the general trend of flow
as inferred from surface sigma-t contours. This tentative con-
clusion is based only on a rather small number of cases and further
investigation of this relationship should be conducted.

G. TEMPERATURE - SALINITY RELATIONSHIPS AT STATIONS

2 AND 3

The temperature - salinity curves shown in Figures 80 through
94 were typical curves selected from each month of the study. They
were drawn from Nansen cast data obtained at Stations 2 and 3 during
the weekly bay cruises. The solid line represents the temperature -
salinity curve for Station 2 while the dashed line depicts the curve
for Station 3.

Figure 78 shows the monthly curves for Station 2 and Figure 79
shows the monthly curves for Station 2. These monthly curves were
drawn from the temperature - salinity curves described above. There
was a wide variation in the characteristics of the upper layers of
these waters (less than 200 meters) at both stations but the deeper
layers were generally consistent throughout the fourteen months.
The waters in the lower layers (greater than 200 meters) were

57

classified as North Pacific Intermediate Waters. Station 3 showed
more variability than Station 3 in these deeper waters. This was
probably because this outer station was affected to a greater degree
by the variations in the California and Davidson Currents.

There seemed to be several distinct periods in the temperature -
salinity relationship of surface waters at Stations 2 and 3. The
September 1971 and October 1971 curves were probably the remnants
of the summer season of 1971. The months of November 1971 through
January 1971 showed a decrease in temperature but maintained the
same salinity as present in earlier months. The months of February
1972 through April 1972 maintained the same surface temperatures as
the previous three months, but there was a 0. 3 to 0.4 parts per
thousand decrease in the surface salinities. May exhibited the lowest
temperatures in the upper layers and a marked increase in the surface
salinities from the earlier months. Both of these features were
most likely caused by the cold and more saline waters at greater
depths being lifted to the surface by the upwelling process. June
appeared to be a transition month from the cold, low saline months
of November 1971 through May 1972 to the warm, high salinity months

from July 1972 through October 1972. This last group of months

o

showed an increase in surface temperatures of up to 4 C over the

previous months. The salinities of this last period were lower than
those observed in May but higher than those obtained during February,
March and April.

58

IV. CONCLUSIONS AND RECOMMENDATIONS

A. CONCLUSIONS

The coastal upwelling index computed for 36 N, 122. W by the
National Marine Fisheries Service and Fleet Numerical Weather
Center was found to be a reasonable indicator of the isotherm depths
and sea surface temperatures in Monterey Bay in relation to the long
term isotherm depths and sea surface temperatures computed by
Lammars for the fourteen months (September 1971 -October 1972)
included in this study. During the months when upwelling was more
intense than denoted by the 20 year mean value of the index, the iso-
therms were shallower and the sea surface temperatures were
lower than normal. During the months when the coastal upwelling
index indicated v/eaker than normal upwelling, the isotherms were
found at greater depths and the sea surface temperatures were
warmer than depicted by the long term mean values.

There seemed to have been several anomalous features in the
1971-72 oceanographic seasons when compared to those described
by Skogsberg and Bolin. The Davidson Current apparently com-
menced as early as October 1971, about one month ahead of its usual
starting date. It also appears to have lasted about four months
longer than normal, ceasing its flow in May instead of January.

59

Thus the Davidson Current was present during the first portion of
the usual Upwelling Period. During this study, the minimum depths
of the isotherms were obtained one to two months earlier than in the
description of the Upwelling Period as given by Skogsberg and Bolin.
The Oceanic Period, which is normally only present in September
and October, appears in 1972 to have commenced at the end of June
or early July and lasted only through October. Thus, the ocean-
ographic seasons as described by Skogsberg and Bolin occurred
earlier and lasted longer in the time span of fourteen months covered
in this study.

The monthly mean patterns of sea surface temperature usually
had a relative cold area located over the axis of the Monterey Sub-
marine Canyon and the outer edge of the southern shallows. It could
not be determined if this cool region was caused by the presence of
water upwelled in this location or whether it had been advected into
the region.

The monthly mean topographies of the 10 C surface indicated
that there was generally a thicker layer of warm water located over

the canyon axis which was generally consistent with the long term

o
means. During months of strong upwelling the 10 C topography

showed weak horizontal and vertical gradients. The months of weak

upwelling showed strong gradients in both the horizontal and vertical

directions. It appeared that during these weak upwelling months that

60

the cold water flowed up the sides of the Monterey Submarine Canyon
and seeped into the shallow regions of the bay at or near the bay
floor.

It was found for the few parachute drogue studies available that
the contours of surface sigma-t values were reasonable indicators
of the current flow as described by the drogue paths. The monthly
mean sea surface temperature contours for June 1972 and August and
September 1972 were also good indicators of the general flow of the
current as denoted by the drogue paths of 20-21 June 1972 and 30-31
August 1972. The topographies of various isothermal surfaces,
both monthly mean surfaces and those obtained the day of the drogue
studies, were not reliable indicators of the current as described by
the drogue paths. It was thought that these surfaces would be related
to the mean density structure of the bay and thus would be indicators
of the general mean flow in the bay. Strong geostrophic flow would
not be expected during these summer months diie to the weak horizontal
gradients of the isotherm so that good correlation with direct currents
would not necessarily be expected.

The large number of north-south geostrophic current profiles
computed between Stations 2 and 3 showed that the maximum current
speed was usually less than 20 centimeters per second and that this
maximum speed occurred at the surface or in the upper 100 meters.
The overall direction of the geostrophic current was toward the north

61

from September 1971 through May 1972. From June 1972 through
October 1972 the general direction of the current between Stations
2 and 3 was to the south.

A comparison between the current flow indicated by the available
sigma-t contours and the flow predicted by Garcia's [1971] numerical
model of current patterns in the bay was conducted. It was found
that there was good agreement between the overall current flow
between Stations 2 and 3 and the current flow in the bay. Thus it
appears from this limited investigation that Garcia's numerical model
current pattern are indicative of flow in the bay.

The temperature - salinity curves for Stations 2 and 3 showed
several periods when the surface waters at these stations had the same
characteristics. The period from November 1971 through April 1972
showed cold-low salinity water to have been present at these stations.
In the months from June 1972 to October 1972 the surface waters
were warmer and more saline than in the previous period. The curves
for all months at both stations were nearly the same for the deeper
layers and this water was classified as North Pacific Intermediate
Water.

A comparison of the current flow between Stations 2 and 3 and
the current flow in the bay was conducted. It was found that the
relationship between the direction of the overall offshore flow and the
flow within Monterey Bay was the same as predicted by Garcia's

62

numerical model. This was done for only a few days when data was
available. This should be used with caution but the preliminary
results were encouraging.

The one overall description of the waters of Monterey Bay that
is appropriate at all times is that these waters are extremely variable.
Evidence of this variability was shown in the large weekly fluctuations
of the depths of isotherms at all stations in the bay, the various
oceanographic seasons occurring earlier and lasting longer than
described in past investigations and the change in the characteristics
of the surface waters at Stations 2 and 3 on a monthly basis.

B. RECOMMENDATIONS

It is recommended that the bay cruises be continued on a weekly
basis. The data base for Monterey Bay could be greatly improved if
the Naval Postgraduate School, Moss Landing Marine Laboratory and
Hopkins Marine Station coordinated their weekly and monthly cruise
schedules so that the respective cruises would take place on the same.
day. This would increase the amount of synoptic data and events
occurring in the bay could be described.

In order to increase the usefulness of the data from the weekly
bay cruises, it is recommended that a new station be established at
least 22 kilometers directly north of Station 3 and that a Nansen or
STD cast be condticted there and that surface salinity samples be

collected at all stations. The new station would allow for the com-
putation of the east-west component of the geostrophic current while
the surface salinities would permit the calculation of surface sigma-t
values so that the use of this parameter can be further investigated
in determining surface current patterns in Monterey Bay.

It is also recommended that at least a year-long series of direct
current measurements be taken in order to obtain a better under-
standing of current patterns in Monterey Bay.

64

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60

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Figure 17. Comparison of Monthly Sea Surface Temperature
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81

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Figure 18. Comparison of Monthly Sea Surface Temperature
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16

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60 80 100 120 140 160 180 200 220 240 260 280

DEPTH ( M) STATION 4

Figure 19- Comparison of Monthly Depth of 9 C Isotherm at
Station 4 and Station 8 to Long Term Mean Monthly Depths

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MONTEREY

112

121° 50'

^C^>

Figure 49.
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20-2 1 July 1972

113

121° 50'

Figure 50.
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3-4 August 1972

MONTEREY

114

115

Figure 52.

Comparison of Inferred Flow
from 10 C Monthly IsothermaJ
Surface to Drogue Paths on
20-2 1 June 1972

r

MONTEREY

116

121° 50'

2 70

Figure 53.

Comparison of Inferred Flow

from 10 C Monthly Mean

Isothermal Surface to

Drogue Paths on

30-31 August 1972

50 —

36°40'H

MONTEREY

_J-

117

Figure 54.

Comparison of Inferred Fl
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Surface to Drogue Paths
on 20-21 June 1972

JL.

118

Figure 55.

Comparison of Inferred Fl
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Temperatures to Drogue
Paths of 20-21 June 1972

119

120

121

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121° 55'

121° 50'

NPS

MLML G
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Figure 58.

Moss Landing Marine
Laboratory and Hopkins
Marine Station Cruise
Stations where Samples
were Collected

122

Figure 59.
Comparison of
from Surface C
19-21 June to D
Paths on 20-21

123

Figure 60.

Comparison of Flow Inferred
from Surface Contours of
t of 28-30 August 1972
to Drogue Paths of 30-31
August 1972.

124

Figure 61. Stations Where Geostrophic Current Information

was Available

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Inferred Current Based on
Surface Values of 0 •£
20-22 Oct 71.

-L™

133

122°00

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121° 50'

4 19 Nov 71

• 5 N

1 — -vj • 'i

Figure 69.

Inferred Current Based
Surface Values of CT^
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36°40'-

134

135

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Figure 72.

Inferred Current Based
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17-19 April 72

137

138

139

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Figure 79. Typical Monthly Temperature-Salinity Curves

at Station 2

144

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Figtire 80. Typical Monthly Temperature-Salinity Curves

at Station 3

145

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Figure 81. Typical Temperature-Salinity Curves
for Stations 2 and 3 for September 1971

146

33.00

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Figure 82. Typical Temperature-Salinity Curves
for Stations 2 and 3 for October 1971

147

3 3.00 .20 .40 .60

Salinity %o

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_T__ , — ,_™T__ , p- ( — 1 —

18
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Figure 83. Typical Temperature -Salinity Curves
for Stations 2 and 3 for November 1971

148

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60 .80 34.00 .20 .40 .60 .80 35.00

T —

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Figure 84. Typical Temperature-Salinity Curves
for Stations 2 and 3 for December 1971

149

3 3.00 .20 .40
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Figure 85. Typical Temperature-Salinity Curves
for Stations ?. and 3 for January 1972

150

3 3.00 ?0

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Figure 86. Typical Temperature -Salinity Curves
for Stations 2 and 3 for February 1972

151

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17
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15
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7
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Salinity %o
.80 34.00 .20 .40 .60 .80 35.00

16MAR 72

Figure 87. Typical Temperature-Salinity Curves
for Stations 2 and 3 for March 1972

152

33.0 0 .20 40

— y~ (—

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17

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Figure 88. Typical Temperature -Salinity Curves
for Stations 2 and 3 for April 1972

153

3 3.0 0 .20 .40 .60

SoiiniSy %0

80 34.00 .20

~i — r — — t—

.40 .60 .80 35.00

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17
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16 MAY 72

1000

Figure 89. Typical Temperature-Salinity Curves
for Stations 2 and 3 for May 1972

154

3 3.00 .20 .40 .60

Salinity °/0O

.80 34.00 .20 .40 .60 .80 35.00

—| — -i — r— — -i —

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Figure 90. Typical Temperature-Salinity Curves
for Stations 2 and 3 for June 1972

155

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Figure 91. Typical Temperature-Salinity Curves
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156

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Figure 92. Typical Temperature-Salinity Curves
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157

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BIBLIOGRAPHY

1. Anderson, C. A., Thermal Conditions in Monterey Bay during

September 1966 through September 1967 and January 1970
through June 1971, Master's Thesis, Naval Postgraduate
School, Monterey, California, September 1971.

2. California Cooperative Oceanic Fisheries Investigations Atlas

No. 4. , Geostrophic Flow of the California Current at the
Surface and at 200 Meters, by J. G. Wylie, December 1966.

3. California Cooperative Oceanic Investigations Atlas No. 16,

Release and Recovery Records of Drift Bottles in the
California Current Region 1955 through 1971, by F. J.
Crowe and R. A. Schwartzlose, June 1972.

4. Garcia, R. A. , Numerical Simulation of Currents Monterey

Bay, Master's Thesis, Naval Postgraduate School,
Monterey, California, 1971.

5. Jennings, F. D. and R. A. Schwartzlose, "Measurements of

the California Current in March 1958, " Deep Sea Research,
v. 7, p. 42-47, I960.

6. Lainmars, Lennis Larry, A Study of Mean Monthly Thermal

Conditions and Inferred Currents in Monterey Bay,
Master's Thesis, Naval Postgraduate School, Monterey,
California, June 1971.

7. Leipper, D. F. ', "A Sequence of Current Patterns in the Gulf

of Mexico, " Journal of Geophysical Research, v. 75, No. 3,
p. 637-657, 20 January 1970.

8. McClelland, J. J. , Jr. , An Oceanographic Study of Thermal

Changes in Monterey Bay, California, September 1971-
January 1972, Master's Thesis, Naval Postgraduate School,
Monterey, California, March 1972.

9. Moss Landing Marine Laboratories Publication 72-5, Tidal

Oscillations at the Head of Monterey Submarine Canyon and
Their Relation to Oceanographic Sampling and the Circulation
of Water in Monterey Bay, by William W. Broenkow and
Scott J. McKain, September 1972.

161

10. Office of Naval Research Contract NGONR-25127, Hydrographic

Data from the Area of the Monterey Submarine Canyon,
195 1- 1955, by R. L. Bolin and Collaborators, p. 1-10 1 ,
30 July 1964.

11. Reid, J. L. , "Measurements of the California Countercurrent

at a Depth of 250 Meters, " Journal of Marine Research,
v. 20, p. 134-137, 1962.

12. Reid, J. L. , G. I. Roden and J. G. Wylie, "Studies of California

Current Systems, " CALCOFI Progress Report 1 July 1956 to
1 January 1958, Marine Research Committee California
Department of Fish and Game, p. 27-56, 1958.

13. Reid, J. L. and R. A. Schwartzlose, "Direct Measurements of

the Davidson Current off Central California, " Journal of
Geophysical Research, v. 67, No. 6, p. 2481-2497, June
1962.

14. Skogsberg, T. , "Hydrography of Monterey Bay, California

Thermal Conditions, 1929-1933, " Transactions of American
Philosophical Society, v. 29, December, 1936.

15. Stodard, H. S. , Feasibility Study on the Utilization of Parachute

Drogues and Shore-Based Radar to Investigate Surface
Circulation in Monterey Bay, Master's Thesis, Naval
Postgraduate School, Monterey, California, 1971.

16. Sverdrup, H. U. , M. W. Johnson, and R. H. Fleming, The

Oceans: Their Physics, Chemistry and General Biology,
Prentice-Hall, 1942. ~

17. U. S. Department of Commerce, NOAA Technical Report NMFS.

SSRF by A. Bakum, in press.

18. Wooster, W. S. and Reid, J. L. , "Eastern Boundary Currents, '

in The Sea, Volume 2, edited by M. N. Hill, John Wiley and
Sons, New York, 1963.

162

INITIAL DISTRIBUTION LIST

No. Copies

1. Defense Documentation Center 2
Cameron Station

Alexandria, Virginia 22314

2. Library, Code 0212 2
Naval Postgraduate School

Monterey, California 93940

3. Department of Oceanography, Code 58 3
Naval Postgraduate School •

Monterey, California 93940

4. Professor D. F. Leipper, Code 58Lr 1
Department of Oceanography

Naval Postgraduate School
Monterey, California 93940

5. Professor E. B. Thornton, Code 58Tm 1
Department of Oceanography

Naval Postgraduate School
Monterey, California 93940

6. Assoc Professor J. B. Wickham, Code 58Wk I
Department of Oceanography

Naval Postgraduate School
Monterey, California 93940

7. Mr. W. W. Reynolds, Master 1
R/V ACANIA

Department of Oceanography
Naval Postgraduate School
Monterey, California 93940

8. Mr. J. Norton 1
Department of Oceanography

Naval Postgraduate School
Monterey, California 93940

9. LT David H. Moomy, USN 2
SMC 1897

Naval Postgraduate School
Monterey, California 93940

10. Dr. Ned A. Ostenso
Code 408D

Office of Naval Research
Arlington, Virginia 22217

11. Oceanographer of the Navy
The Madison Building

732 N. Washington Street
Alexandria, Virginia 22314

12. Director

Hopkins Marine Station of Stanford University
Pacific Grove, California 93950

13. Director

Moss Landing Marine Laboratories of the

California State Colleges
Moss Landing, California 95039

14. Mr. A. Bakun

National Marine Fisheries Service
Monterey, California 9.3940

15. Association of Monterey Bay Area Governments

(AMBAG)
798 Cass Street
Monterey, California 93940

16. Professor S. P. Tucker, Code 58
Department of Oceanography
Naval Postgraduate School
Monterey, California 93940

17. Mr. M. J. Doyle, Jr.
Department of Engineering Research
Pacific Gas and Electric Company
4245 Mollis

Emeryville, California 9460 8

18. Office of Naval Research
Code 480

Arlington, Virginia 22217

164

Unclassified

pcurity Classification

DOCUMENT CONTROL DATA -R&D

(Security ( lessilic at ion of Jjjje. body of Abstract and indexing annotation must be enforce/ when the overe.lt report ts classified)
CINA1INC ACTIVITY (Corporate vutltor) \ia. REPORT SECURITY CLASSIFICATION

Naval Postgraduate School
Monterey, California 93940

Unclass Lfied

26. GROUP

PORT TITLE

Temperature Variations Throughout Monterey Bay
September 1971-October 1972

;SCRIPTIVE NOTES (Typo of report and, inclusive dates)

Master's Thesis; March 1973

JTHORI5I (First nemo, middle tnltlul, l«»t neme_)

David H. Moorny

PORT DATE

March 1973

OK TRACT OR GRANT NO.

■> ROJEC T NO.

7o. TOTAL NO. OF PAGES

166

76. NO. OF REFS

60. ORIGINATOR'S REPORT NUMBERIS)

»6. OTHER REPORT hiOiS} (Any other numbore that may bo mmalffrted
thie report)

DISTRIBUTION STATEMENT

Approved for public release; distribution unlimited.

SUPPLEMENTARY NOTES

12. SPONSORING MILITARY ACTIVITY

Naval Postgraduate School
Monterey, California 93940

ABSTRACT

Temperature data was obtained at nine stations in Monterey Bay on a
weekly basis from September 1971 to October 1972. Monthly mean depths of
the isotherms were computed and compared to the long term mean depths of
these isotherms. Sea surface temperature patterns and the topographies of the
10°C surface were drawn. It was found that the period from October 1971 to
May 1972 was colder than normal while the months from June 1972 to October
1972 were warmer than usual. The NMFS coastal upwelling index was a relative
indicator of isotherm depth in relation to the long term mean depths of these
isotherms.

Quasi- synoptic observations between two offshore stations indicated that the
north-south component of the offshore current seldom exceeded 20 cm/sec. The
inferred flow from the surface <T contours and the topographies of isothermal
surfaces were compared to current flow determined by drogue measurements.
The overall direction of the offshore current and the inferred flow in the bay
compared reasonably well to the proposed flow in the numerical model of
current patterns in the bay by Garcia [1971].

D/Lr..1473

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(PAGE I )

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165

Unclassified

Security CIosBilicetion

A-31408

, MC»

Unclassified

Security Clans if ir-ution

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LINK A LINKS

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A- 31 409

Thesis

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Temperature variations throughout Monter

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3 2768 002 04739 1 ,
DUDLEY KNOX LIBRARY '