Trends and variability of yearly mean sea-level, 1893-1972

NOAA Technical Memorandum NOS 13

TRENDS AND VARIABILITY OF YEARLY MEAN SEA LEVEL
1893-1972

Steacy D. Hicks and James E. Crosby

Rockville, Md.
March 1974

NATIONAL OCEAN (@))

noa NATIONAL OCEANIC AND
ATMOSPHERIC ADMINISTRATION SURVEY
LL

NOAA TECHNICAL MEMORANDA
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C&GSTM 1 Preliminary Measurements With a Laser Geodimeter. S. E. Smathers, G. B. Lesley, R. Tomlin-
son, and H. W. Boyne, November 1966. (PB-174-649)

C&GSTM 2. Table of Meters to Fathoms for Selected-Intervals. D. E. Westbrook, November 1966. (PB-174-
655) ;

C&GSTM 3. Electronic Positioning Systems for Surveyors. Angelo A. Ferrara, May 1967, (PB-175-604)
C&GSIM 4 Specifications for Horizontal Control Marks. L. S. Baker, April 1968. (PB-179-343)

C&GST™ S Measurement of Ocean Currents by Photogrammetric Methods. Everett H. Ramey, May 1968. (PB~
179-083) ;

C&GSTM 6 Preliminary Results of a Geophysical Study of Portions of the Juan de Fuca Ridge 7nd Blanco
q Fracture Zone, William G. Melson, December 1969. (PB-189-226) ‘

C&GSTM 7 Error Study for Determination of Center of Mass of the Earth From Pageos Observations. K. R.
Koch and H. H. Schmid, January 1970. (PB-190-982)

C&GSTM 8 Performance Tests of Richardson-Type Current Meters: I. Tests 1 Through 7. R. L. Swanson
and R, H. Kerley, January 1970. (PB-190-983)

NOAA Technical Memoranda

NOS 9 The Earth's Gravity Field Represented by a Simple Layer Potential From Doppler Tracking of
Satellites. Karl-Rudolf Koch and Bertold U. Witte, April 1971. (COM-71-00668)

NOS 10 Evaluation of the Space Optic Monocomparator. Lawrence W. Fritz, June 1971. (COM-71-00768)

NOS 11 Errors of Quadrature Connected With the Simple Layer Model of the Geopotential. Karl-Rudolf

Koch, December 1971. (COM-72-10135)

NOS 12 Trends and Variability of Yearly Mean Sea Level 1893-1971. Steacy D. Hicks, March 1973.
(COM-73-10670)

SS a oe

NOAA Technical Memorandum NOS 13

TRENDS AND VARIABILITY OF YEARLY MEAN SEA LEVEL
Its} SS IL) 7/72

Steacy D. Hicks and James E. Crosby

Rockville, Md.
March 1974

UNITED STATES NATIONAL OCEANIC AND NATIONAL OCEAN
DEPARTMENT OF COMMERCE ATMOSPHERIC ADMINISTRATION SURVEY
Frederick B. Dent, Secretary Robert M. White, Administrator Allen L. Powell, Director

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TRENDS AND VARIABILITY OF YEARLY MEAN SEA LEVEL, 1893-1972

Steacy D. Hicks
and
James E. Crosby
National Ocean Survey, NOAA
Rockville, Maryland

ABSTRACT. Sea-level trends, their standard
errors, and variability are presented in
tabular form for 50 locations along the coasts
of the United States. The values are given
for the entire series length at each station,
the oldest dating from 1893 at New York. For
intrastation comparisons, values also are
given for the longest length of series common
to 46 of the stations, 1940-72. Graphs of
yearly mean sea level, upon which the calcu-
lations were performed, are plotted for 44
stations.

1. INTRODUCTION

This Technical Memorandum is directed toward the manage-
ment fields of wetlands preservation, pollution abatement and
control, conservation, coastal zone management, and global
energy; the engineering fields of beach erosion, harbor and
waterway construction, shore and sea boundaries, and coastal
inundation; and the scientific fields of glaciology, physical
and geological oceanography, meteorology and climatology,
tectonics, and geodesy. Since the uses of the calculations may
vary greatly, no interpretive text is included. This publica-
tion will be issued annually; each issue will incorporate the
new yearly mean sea level values in each tabulated calculation
and graph.

2. EXPLANATION OF TRENDS AND VARIABILITY

Yearly mean sea level is the arithmetic mean of hourly sea
level heights obtained from an analog tide gage over a period
of one calendar year. The tide gage, often located on a pier,
continuously measures sea-level heights relative to the land
adjacent to the station location. The gage is connected to
bench marks on the adjacent land by precise first-order lev-
eling. If possible, the bench marks are located in bedrock.

One table and nine illustrations show the trends and
variability of yearly mean sea level at permanent tide stations
operated by the National Ocean Survey (NOS). Column 1 of the
table lists all of the NOS-operated stations that were in opera-
tion by 1939 and that had very few and short breaks in measure-
ment. In addition, all permanent stations in the greater New
York Bight area are included. The inclusive dates of each
station series are given in column 2. Where the length of a
break in the series is sufficient to invalidate a yearly mean,
the missing year is shown in column 3.

If a series of yearly mean sea level values is plotted on
a graph of height against date, an apparent secular trend and
yearly variability become evident. ''Secular'' means nonperi-
odic; "apparent'' means it is not known whether the trend is
nonperiodic or is merely a segment of a very long oscillation.
Apparent secular trends in sea level result from glacial-
eustatic, tectonic, and climatological and oceanographic appar-
ent secular trend effects. Columns 4 and 7 show the apparent
secular trend as the slope of a straight line mathematically
fitted through the yearly mean sea level values (see note a on
table). About two-thirds of repeated calculations of the ap-
parent secular trend will differ from the true apparent secular
trend by less than the standard error of slope listed in col-
umns 5 and 8 (see note b on table). About 95% of repeated
calculations of the apparent secular trend will differ by less
than two times the standard error of slope, and practically
all repeated calculations will differ by less than three times
the standard error of slope.

Yearly variability is caused by variations in the mete-
orological and oceanographic parameters of wind, direct atmos-
pheric pressure, river discharge, currents, salinity, and
water temperature. About two-thirds of the yearly mean sea
level values will differ from the straight line slope by less
than the variability given in columns 6 and 9 (see note e¢ on
table). About 95% of the yearly mean sea level values will
differ from the line by less than two times the variability,
and practically all the values will differ by less than three
times the variability.

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TIME, years

1920 1930 1940 1950 1960

Te
PORTLAND, ME. ar!

1910

PORTSMOUTH, N.H.
20

HEIGHT, cm

SCALE, cm

"9 BOSTON, MASS.
5

WOODS HOLE, MASS.
0
NEWPORT, R.I.

NEW LONDON, CONN.

Figure 1.--Change in sea level with respect to adjacent land
for stations from Maine to Connecticut. Straight-line
segments connect yearly mean sea level values. Curved
lines connect yearly values smoothed by weighting array.

TIME, years
1930

1910 1920 1940 1950 1960

1890 1900

WILLETS PT., N.Y.

NEW YORK, N.Y.

HEIGHT, cm

SANDY HOOK, N.J.

20

ATLANTIC CITY, N.J.
15

SCALE, cm

ANNAPOLIS, MD.

BALTIMORE, MD.

Figure 2.--Change in sea level with respect to adjacent land
for stations from New York to Maryland.

TIME, years

1920 1930 1940 1950 1960 1970

WASHINGTON, D.C.

SOLOMONS, MD.

HAMPTON ROADS, VA.
20

HEIGHT, cm

SCALE, cm

5 PORTSMOUTH, VA.
CHARLESTON, S.C.

FORT PULASKI, GA.

Figure 3,--Change in sea level with respect to adjacent land
for stations from the District of Columbia to Georgia.

TIME, years
1930 1940 1950 1960

1970

1910 1920

FERNANDINA, FLA.

MAYPORT, FLA.

HEIGHT, cm

20
MIAMI BEACH, FLA.
15 KEY WEST, FLA.

SCALE, cm

5 CEDAR KEY, FLA.

PENSACOLA, FLA.

Figure 4.--Change in sea level with respect to adjacent land

for stations in Florida.

10

TIME, years
1900 1910 1920 1930 1940 1950 1960 1970

20
EUGENE I., LA.

SCALE, cm

HEIGHT, cm

GALVESTON, TEX.

SAN DIEGO, CALIF.

Figure 5.--Change in sea level with respect to adjacent land
for stations from Louisiana to California.

TIME, years
1890 1900 1910 1920 1930 1940

LA JOLLA, CALIF.
LOS ANGELES, CALIF.
- ALAMEDA, CALIF.
15

SAN FRANCISCO, CALIF.

10
i)
0

CRESCENT CITY, CALIF.

Figure 6.--Change in sea level with respect to adjacent land
for stations in California.

1950 1960 1970

HEIGHT, cm

SCALE, cm

2

TIME, years
1890 1900 1910 1920 1930 1940 1950 1960 1970
Fi pecenmeet aed pon GORA RENAE MPTGR POUT ooaaE vse fotaeen I ectaeegRnges D aeeoenyrer Tso D eae pa ree | eee fee

20
ASTORIA, OREG.

SCALE, cm

SEATTLE, WASH.

NEAH BAY, WASH.

FRIDAY HARBOR, WASH.

5. HEIGH?, cm

KETCHIKAN, AK.

Figure 7.--Change in sea level with respect to adjacent land
for stations from Oregon to Alaska.

13

TIME, years
1930 1940 1950 1960 1970

SITKA, AK.

HEIGHT, cm

20 JUNEAU, AK.

15

SCALE, cm

SKAGWAY, AK.

Figure 8.--Change in sea level with respect to adjacent land
for stations in Alaska.

14

TIME, years
1900 1910 1920 1930 1940 1950 1960 1970
YAKUTAT, AK.
20
15 =
SS
5 =
uit 10 ia
Ss
wn
5
0 HONOLULU, HI.

CRISTOBOL, C.Z.

Figure 9.--Change in sea level with respect to adjacent land for
Yakutat, Alaska, Honolulu, Hawaii, and Cristobal, C.Z.

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