NORA-
Tm) MOS opaA-54Y

NOAA Technical Memorandum NOS OMA 54

WATER LEVEL MEASUREMENTS IN THE POLAR REGIONS:

STATUS AND TECHNOLOGY

\

DOCUMENT
LIBRARY

Woods Hole Oceanographic

Institution

—

Rockville, Maryland
September 1990

Nn O a a NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION

NATIONAL OCEAN SERVICE

Office of Oceanography and Marine Assessment
National Ocean Service
National Oceanic and Atmospheric Administration
U.S. Department of Commerce

The Office of Oceanography and Marine Assessment (OMA) provides decisionmakers with
comprehensive, scientific information on characteristics of the oceans, coastal areas, and
estuaries of the USA. The information ranges from strategic, rational assessments of coastal and
estuarine environmental quality to real-time information for navigation or hazardous materials
spill response. For example, OMA monitors the rise and fall of water levels at about 200
coastal locations of the USA (including the Great Lakes); predicts the times and heights of high
and low tides; and provides information critical to national defense, safe navigation, marine
boundary determination, environmental management, and coastal engineering. Currently, OMA
is installing the Next Generation Water Level Measurement System that will replace by 1992
existing water level measurement and data processing technologies. Through its National Status
and Trends Program, OMA uses uniform techniques to monitor toxic chemical contamination of
bottom-feeding fish, mussels and oysters, and sediments at 200 locations throughout the USA. A
related OMA program of directed research examines the relationships between contaminant
exposure and indicators of biological responses in fish and shellfish.

OMA uses computer-based circulation models and innovative measurement technologies to
develop new information products, including real-time circulation data, circulation forecasts
under various meteorological conditions, and circulation data atlases. OMA provides critical
scientific support to the U.S. Coast Guard during spills of oil or hazardous materials into marine
or estuarine environments. This support includes spill trajectory predictions, chemical hazard
analyses, and assessments of the sensitivity of marine and estuarine environments to spills.
The program provides similar support to the U.S. Environmental Protection Agency's Superfund
Program during emergency responses at, and for the cleanup of, abandoned hazardous waste
sites in coastal areas. To fulfill the responsibilities of the Secretary of Commerce as a trustee
for living marine resources, OMA conducts comprehensive assessments of damages to coastal and
marine resources from discharges of oil and hazardous materials.

OMA collects, synthesizes, and distributes information on the use of the coastal and oceanic
resources of the USA to identify compatibilities and conflicts and to determine research needs
and priorities. It conducts comprehensive, strategic assessments of multiple resource uses in
coastal, estuarine, and oceanic areas for decisionmaking by NOAA, other Federal agencies, state
agencies, Congress, industry, and public interest groups. It publishes a series of thematic data
atlases on major regions of the U.S. Exclusive Economic Zone and on selected characteristics of
major U.S. estuaries. It also manages, for the U.S. Department of the Interior, a program of
environmental assessments of the effects of oil and gas development on the Alaskan outer
continental shelf.

OMA implements NOAA responsibilities under Title Il of the Marine Protection, Research, and
Sanctuaries Act of 1972; Section 6 of the National Ocean Pollution Planning Act of 1978; and
other Federal laws. OMA has three major line organizations: The Physical Oceanography
Division, the Ocean Assessments Division and the Ocean Systems Division.

NOMA

0 0301 O086b8e &

MBL/WHOI

MII

NOAA Technical Memorandum NOS OMA 54

Water Level Measurements in the Polar Regions:
Status and Technology

Eugene M. Russin
Hsing H. Shih
Richard F. Edwing

| FEW AS
Nia ee he
Rene ae HA

Weeds Hole Oceanographic
jasiitution

Rockville, Maryland
September 1990

DENCO

United States National Oceanic and National Ocean Service
Department of Commerce Atmospheric Administration

Robert A. Mosbacher John A. Knauss Virginia K. Tippie

Secretary Assistant Secretary and Assistant Administrator

Administrator

Correspondence relative to this report should be addressed to the authors in care of:

Ocean Services Division

Office of Oceanography and Marine Assessment
National Oceanic and Atmospheric Administration
U.S. Department of Commerce

6001 Executive Blvd., Rm. 110

Rockville, MD 20852

NOTICE

This report has been reviewed by the National Ocean Service of the National Oceanic and
Atmospheric Administration (NOAA) and approved for publication. Such approval does not
signify that the contents of this report necessarily represent the official position of NOAA or of
the Government of the United States, nor does mention of trade names or commercial products
constitute endorsement of recommendation for their use.

TABLE OF CONTENTS

List of Figures

ABSTRACT

1.0 INTRODUCTION

2.0 PRESENT EFFORTS AND TECHNOLOGY

on Background

2.2 The Polar Region Environment

2.3 NOS Efforts

6). Tide Stations

232: Bench Marks

2.3.3. Dinkum Sands Project

2.4 Canadian Efforts

2.5 Other Countries Efforts

Zone Japan

PAIS) 7X U.S.S.R.

gayseh New Zealand

2.6 Recent and Applicable Meetings and Workshops
2.7 Organizations Interested in the Polars Regions
3.0 WHAT NOAA/NOS COULD DO IN THE NEAR-TERM
3.1 Prudhoe Bay Saltwater Treatment Plant

3.2 Thermal Bench Marks

4.0 CONCLUSIONS AND RECOMENDATIONS

4.1 Conclusions

4.2 Recommendations for Future Study and Work

Appendix A. REFERENCES

Appendix B. SELECTED BIBLIOGRAPHY

Page

Sao Oe &) Aaa @ WM D

10

Al

B1

List of Figures

. The Arctic Region

. The Antarctic Region

. NOS Tide Stations in Alaska

. Present Data Acquisition

. Next Generation Water Level Measurement System
. Possible Polar Region Installation

. Dinkum Sands Project Tide Station Installation

. Canadian Developments

Oo ON Ooh WO YO —

. The present system of tidal observation at the Japanese SYOWA Station
10. Pruhoe Bay, Alaska, NGWLMS Site Sketch
11. Thermo Bench Mark

Page
19
20
21
22
23
24
25
26
27
28
29

WATER LEVEL MEASUREMENTS IN THE POLAR REGIONS
STATUS AND TECHNOLOGY

E. M. Russin, H. H. Shih and R. F. Edwing

National Ocean Service, NOAA

ABSTRACT

Continuous sea level measurements have been made and recorded for more than 100 years,
but their importance has increased dramatically in the past few years due to the great international
interest for monitoring global levels in anticipation of climate warming. Since the National Ocean
Service (NOS) is the primary agency for measuring and recording water levels in the United States,
itis being encouraged to increase the number of permanent sea level measuring stations especially
in the polar regions where the data are extremely sparse.

Personnel from the Physical Oceanography Division (POD) and the Ocean Systems Division
(OSD) of the Office of Oceanography and Marine Assessment (OOMA) have been researching the
status of the technology and the requirements for water level measurements in the polar regions
with special emphasis on the needs of NOAA’s Climate and Global Change Program and The Global
Sea Level Observing System, known as GLOSS. It is called GLOSS because it measures the global
level of the sea surface, a smooth level after averaging out waves, tides and meteorological events.
GLOSS, co-ordinated by the Intergovernmental Oceanographic Commission (IOC), provides high
quality standarized data from which valuable sea level products are prepared for international and
regional research programs as well as for practical national applications.

This report includes a survey of the work that NOS and others are or have been doing in this
area and also assesses the state-of-the-art of the technology involved, the potential for future
development, and provides recommendations for near and long-term projects. The report con-
cludes that the technology and techniques exist for making sea level measurements in polar regions
but that they must be site-specific; also, that stable bench mark connections and atmospheric
pressure measurements are mandatory; that the field measurement system should be as
automated as possible; and that near real-time transmission of data is highly desirable to ensure
proper system operation and early availability of information to users. The report recommends the
use of thermal bench marks in certain polar areas and the further development of acoustic and
electromagnetic means of transmitting data from underwater sensors through the ice or land to
nearby shore stations. It also recommends that Prudhoe Bay, AK be established as a pilot station
for further investigations into the measurement requirements of other Arctic stations and that a
cooperative program be initiated with the National Science Foundation for establishing stations in
Antarctica.

1.0 INTRODUCTION

Continuous sea level measurements have been made and recorded for more
than 100 years, but their importance has increased dramatically in the past few
years due to the great international interest for monitoring global levels in
anticipation of climate warming. Some scientists believe that the long term rise
of sea level is due to three processes: thermal expansion of the upper layers of
the ocean, the melting of glacial ice, and the addition of mass from the polar caps.

Since the National Ocean Service (NOS) in the National Oceanic and Atmos-
pheric Administration (NOAA) is the primary agency for measuring and recording
water levels in the United States, it is being encouraged to increase the number
of permanent sea level measuring stations, especially in the polar regions where
the data are extremely sparse.

Personnel from the Physical Oceanography Division (POD) and the Ocean
Systems Division (OSD) of the Office of Oceanography and Marine Assessment
(OOMA) held a meeting on March 29, 1990 to discuss the status and requirements
of water level measurement in the polar regions with special emphasis on the
needs of NOAA’s Climate and Global Change Program and the Global Sea Level
Observing System, known as GLOSS. It is called GLOSS because it measures
the global level of the sea surface, a smooth level after averaging out waves, tides
and meteorological events. GLOSS, co-ordinated by the Intergovernmental
Oceanographic Commission (IOC), provides high quality standardized data from
which valuable sea level products are prepared for international and regional
research programs as well as for practical national applications.

This report is a follow-up to that March 1990 meeting and includes a survey
of the work that NOS and others are or have been doing in this area and also
assesses the state-of-the-art of the technology, the potential for future develop-
ment, and provides recommendations for near- and long-term projects. This
report can be used as a basis for planning, for future discussions within NOS and
NOAA and with other U.S. agencies, and also with other nations.

2.0 PRESENT EFFORTS AND TECHNOLOGY
2.1 Background

The lack of U.S. sea level data in the polar regions is due to the lack of NOS
measurement stations in those areas. Most of the Alaskan stations are sited on

the southern coast of Alaska with very few on the west coast and even fewer on
the north coast. The primary reason for the Alaskan station situation is funding;
an Arctic station could cost up to a million dollars to establish, operate and
maintain properly.

Station data problems occur mainly due to sensor failures or bench mark
instability caused by either ice, icing or the freeze/thaw cycle. Sensor operability
problems have been overcome in some remote areas by the use of gas-purging
(bubbler) instruments connected to an onshore data collection platform. Al-
though such instruments are not successful in areas where ice movements
damage the gas-purging tubing in the ice/shore interface, at least the replacement
cost is relatively low. The bench mark instability problem has been addressed in
areas where no bedrock exists by what is called a thermal bench mark - a type
of thermal pile filled with pressurized carbon dioxide gas used to stabilize the
active layer (freeze/thaw zone) and prevent frost jacking.

The following describes the environment we are addressing and the present
efforts of the United States and other countries in the technology areas related
to making tidal measurements in polar regions.

2.2 The Polar Region Environment

The relatively small tides and tidal currents, and the hostile environment in the
polar regions have, in the past, prevented NOS from conducting any significant
long-term ocean measurements in those regions. The term polar region in this
report is loosely used to include the coastal waters along the north and northwest
of the state of Alaska (i.e., in the Arctic region - the Beaufort Sea in the north,
Chukchi Sea, Bering Strait, and Bering Sea in the northwest), and along the United
States territory in the Antarctic region. See Figures 1 and 2. Around the Arctic
area, NOS maintains only one tide station along the whole northwest and north
coasts of Alaska. In the Antarctica continent, NOAA currently has four measure-
ment stations for climate research programs but no tide measuring stations.

Because of the hostile conditions, environmental data for the polar regions
are scarce. A general description of the environment of the polar regions is as
follows:

Air Temperature: -17° C to +5° C along the coasts in the Arctic, colder
toward the interior, and much colder in the Antarctic region.

Water Temperature: -2°C to +20°C.

Ice: Winter is 8 to 9 months long (from mid-September through late May in
the Arctic), extensive ice covers the water (from the coast to a few kilometers
offshore in the Arctic, with thickness up to 3 meters); there is significant ice
movement (with velocities in the order of several cm/sec) after ice break-up
(including drift of large ice bergs). The extent of the ice cover varies with the
seasons.

Land: Snow covered during the winter. The ground is perennially frozen to
610 meters depth (permafrost). Surface thawing causes upheaval. Glacial
rebound also causes vertical land movement.

Sunlight: Weak due to low sun altitude above the horizon.
Wind: Polar winds prevail most of the time.
Tides: Low tidal amplitudes (less than 100 cm).

Waves: Non-tidal water fluctuations - storm surges and low atmospheric
pressure movement-induced long period fluctuations are frequent and often
overshadow the tide. Extensive ice cover may affect both the amplitude and
phase of the tide.

Currents: Low speed (less than one-half meter per second) in offshore, and
higher (up to several meters per second) in certain near coastal areas. An ice
motion-induced boundary layer flow extending about 30 meters below the surface
also exists.

Because of the above environmental conditions, the sensors or equipment
one designs or selects for use in the polar areas must be capable of operation at
very low temperatures with a limited power supply and have greater sensor
Stability and system reliability than equipment used in less hostile regions.
Batteries are considered the most reliable power source. Solar power is not viable
due to the low percentage on sun exposure but winds could be a possible
supplemental power source in some areas. Due to the remoteness of the
measurement sites, the capability of automated data collection and transmission
is most desirable if only to monitor system performance as aminimum. Additional
design considerations include preparing for ice cover in the long winter time and
ice break-up and drifting during summer.

2.3 NOS Efforts

2.3.1 Tide Stations

NOS’s experiences with water level measurements in polar regions have been
only in the Arctic in Alaskan waters north of the Aleutians. There are presently
16 permanent National Water Level Observation Network (NWLON) stations
operating in Alaskan coastal waters (See Figure 3). Only one of them, Prudhoe
Bay, is located in Arctic waters, and it is presently operated on a seasonal basis
(July - September) although there are plans to make it a year-round station
starting this year. There have been approximately 1,100 short-term historical
stations established in Alaska, but only 20% of them were north of the Aleutians.
The majority of these stations were operated during the summer months, and
most utilized bottom-mounted, pressure-type gauges whereas a typical NOS
primary tide station (Figure 4) operated year-round would have an Analog to
Digital Recorder (ADR) gauge with a float inside a 12-inch stilling well and a
bubbler gauge as a back-up.

In general, the combination of insufficient resources and the harsh Arctic
winter has prevented the establishment of any long-term, year-round NOS water
level stations to-date. The specific obstacles to establishing Arctic tide stations
with NOS’s present water level measurement technology, whether it be the older
ADR or the newer Next Generation Water Level Measurement System
(NGWLMS), can be summarized as follows:

e Lack of vertical support structures for stilling and protective wells;
e Ice pack movement, shallow water depths, freezing wells;
e Bench mark instability; and

e Difficulty and cost of transportation, logistics, utilities, maintenance, etc.
due to the remoteness of the sites.

Although the NGWLMS uses an air acoustic device as its primary water level
sensor, and therefore also requires a support structure, it can also take inputs
from pressure transducers or other underwater sensors and transmit the data via
the GOES satellite communication system so that system performance can be
monitored and users receive the data in near real-time (see Figure 5). ANGWLMS
unit with an acoustic water level sensor has been recently installed, however, in

Prudhoe Bay, AK - only because that is a unique Arctic facility as explained in
Section 3.1. A possible installation of an NGWLMS Data Collection Platform
(DCP) with a bubbler system under the ice is illustrated in Figure 6.

The few existing Arctic marine facilities are typically gravel causeways extend-
ing out into the shallow waters, sometimes miles from shore. They are built with
a low profile and sloping sides to minimize damage from ice pack movement.
Sheet pile is used infrequently along the causeways for various purposes.
However, ice scouring and the shallow water depths make it impossible to operate
through the winter any system attached to the sheet pile. Even when wells are
protected from destruction by ice movement, it is very difficult to prevent the water
from freezing inside the wells.

There have been a few stations designed for year round operation on the
gravel causeway type facilities. A sump-type design was utilized to avoid some
of the problems discussed above. The installation cost of this type station is very
high (Several hundred thousand dollars) and none have been built.

2.3.2 Bench Marks

Bench mark stability is essential to preserving the datums established at a
site. Bench mark stability has been a problem in the Arctic region due to the lack
of bedrock and a large active zone. The lack of bedrock (and large concrete
structures) eliminates the most stable, easily established type of bench mark. The
large active zone, the layer of earth where a jacking action is produced by the
freeze-thaw cycle, renders all monument and pipe marks, and a large number of
Class B (unsleeved) deep rod marks, unstable. Permafrost, in itself, does not
cause instability. High stability bench marks can be established in permafrost
areas by anchoring the bench mark into the permafrost. In areas where per-
mafrost does not exist, Class A (sleeved) bench marks can be established which
are insulated from the active zone. Establishing permafrost-anchored and Class
A bench marks is expensive and difficult to do in remote areas due to the need
to augur a 1-inch diameter guide hole.

The remoteness of the arctic region has obvious impact on site accessibility,
utilities service, logistics, available resources, maintenance, etc. all of which can
be significant cost drivers in addition to installation costs.

Tidal datums, and the marine boundaries determined through their estab-
lishment, have been an important issue in the Arctic over the past two decades
because of ownership claims. Millions of dollars have been at stake in State
versus Federal ownership of oil leasing plots. The Bureau of Land Management
has been surveying coastal lands for the purpose of restoration of the Federal
lands to the State and native corporations; the Extended Jurisdiction Zone (200
mile boundary) has been determined; and NOAA has been conducting
hydrographic surveys and mapping in the Arctic. The private sector uses tidal
datums for artificial island construction, marine operations and other oil industry
related activities. These projects all require tide data, to varying degrees of
accuracy and for differing lengths of time, that has not been previously available
in this region. These requirements, and the inability of standard technology and
methods to satisfy them, has resulted in development and experimentation with
new and improved procedures and instrumentation in an attempt to collect the
needed tide data.

2.3.3 Dinkum Sands Project

Much of the search for new technology or procedures for making tide
measurements in the polar regions has been performed in cooperation with the
State of Alaska and other Federal agencies due to the common need for the data.
The most ambitious, and costly, project was the Dinkum Sands project. An
attempt was made to collect a full year of data off the coast of the north slope
using standard technology (ADR & bubbler gauges) so that the tidal datums
established would be defensible in court. Three long-term stations were estab-
lished on three small, remote gravel islands for redundancy. The fully enclosed,
heated, shelters (see Figure 7) were installed on specially-designed support
platforms, heat tracing was used in the steel reinforced stilling wells, heated oil
was dripped around the wells to prevent ice formation, bottom-mounted pressure
gages supplemented the standard gages, and various other methods were
employed to collect the data. Specially designed, sleeved, deep-rod bench
marks were installed (and sometimes leveled to) while under ice pack cover. A
full year of data was collected at one station at a cost of over $ 1 million.

Other attempts have centered around installing bottom-mounted pressure
gauges but these devices have their own set of problems. Pressure gages are
inherently less accurate than ADRs and must be corrected for barometric
pressure and density variations; it is difficult to establish a physical reference point

on them and to survey to it; and also hard to maintain their stability on the ocean
bottom. If the entire instrument package is underwater, proper operation is a
continual verification problem. If the data recorder is land-based, the cabling is
extremely difficult to protect, particularly at the shore/sea interface. Bottom-
mounted pressure gauges have been installed several times by the State of
Alaska and it’s contractors with limited success.

Short-term data requirements, mostly for hydrographic or photogrammetric
operations, are met simply by conducting measurements during the ice-free
summer months. Standard bubbler pressure gages are used as they are
relatively easily transported and installed in remote and/or rugged areas. In
situations where staff installations are difficult or subject to constant destruction
from storms, several alternative methods are available. Sometimes a rod is driven
into the ocean bottom in a shallow area. The high point of the rod is connected
by survey levels to the bench mark net, and a staff is held on the high point for
staff readings during an observation. The equivalent of a staff reading may also
be made by leveling from a bench mark to the waters edge, if sea conditions are
calm enough. These methods are dependent upon reasonably sheltered loca-
tions, however.

2.4 Canadian Efforts

With the discovery of oil and gas in the Canadian Arctic and subsequent
decisions to transport these products to southern markets by sea, the Canadian
Hydrographic Service (CHS) increased its involvement in collecting arctic tidal
measurements. Initially, the emphasis was directed towards collecting short-term
tidal records in order to obtain a general knowledge about tidal propagation
through the complex archipelago in the Canadian Arctic. The method used to
collect these data consisted of deploying self-recording pressure gauges on the
sea bed and recovering the gauges after a specified elapsed time. The data
collected from these short-term deployments were generally not corrected for
atmospheric pressure variations and were not tied to bench marks.

In 1985, the CHS developed a permanent gauging system with limited
application in the Arctic. This gauge used a conventional gas-purge system to
measure sea levels. The system is connected to a brass orifice which is located
in a protective housing attached to a wharf face. Data collected by the gauge is

transmitted to satellite (ARGOS) at regular intervals and processed later in
Burlington.

In 1987, the CHS commissioned the Bedford Institute of Oceanography (BIO)
to design and develop an atmospheric pressure-measuring system and tide
gauge capable of withstanding arctic conditions for an entire year. In August
1988, BIO successfully demonstrated such a system off the coast of Labrador
using a air pressure sensor manufactured by Atmospheric Instrumentation
Research, Inc.(AIR Inc.) that is accurate to +0.7 millibar and consumes very little
power. BIO is presently working on a satellite data link in order to allow the
collected data to be transmitted to an operating center on an hourly or daily basis.
To avoid using a physical link between the two devices, and to avoid the inherent
problems of communicating through the ice/water barrier, the tide gauge will
transmit ultra-low frequency electromagnetic signals to the data recording system
through the intervening rock. Figure 8 is an artist’s conception of the system.
Electromagnetic energy has been used in mines in South Africa to communicate
through rock and has proved viable for short distances. A short cable will be
used to link the tide gauge to the electromagnetic communications link, located
nearby on the sea bottom.

NOS is closely monitoring the progress of BIO and the Canadian
Hydrographic Service with the hope that we can benefit from this important
research project. Mr. George Steeves, the systems engineer in charge of the
project, hopes to have a system with an electromagnetic communications link
ready for testing near BIO in the winter of 1990-91.

2.5 Other Countries’ Efforts

2.5.1 Japan

Japan has three observation bases in Antarctica - two of them are inland and
the other is coastal. The coastal base, SYOWA STATION, was established in
1958 on the East Ongul Island which is in the face of the Indian Ocean about 5
kilometers off the Antarctic continent. In 1987, a new type of tide gauge using a
quartz oscillator as a sensor was installed at the SYOWA STATION (see Figure
9). In the tide observation hut there is a junction box with a heater to protect the
equipment from freezing. The heater is designed to work when the air tempera-
ture falls below -10° C. The signal cable from the underwater unit to the junction

box is protected with hard plastic tubing. The tide gauge has an air venting tube
from the junction box to the underwater unit through the cable together with the
signal lines and DC power supplying lines in order to make corrections for the
effect of the atmospheric pressure automatically.

2.5.2 U.S.S.R.

Russian activities regarding sea-level measurements at Soviet Antarctic sta-
tions are performed by the Arctic and Antarctic Research Institute of the USSR.
Due to severe ice conditions no permanent sea-level observations have been
made at Soviet Antarctic stations. Some rough sea-level observations have been
made at the Stations Bellingshausen and Russkaya and, occasionally, at the
Station Molodezhnaya. There are plans to obtain regular sea-level observations
at some Soviet Antarctic stations in connection with the GLOSS and WOCE
programs. This will need, however, cooperation with other countries with regard
to the establishment of modern tide gauges and exchange of sea-level data with
other Antarctic stations.

2.5.3 New Zealand

New Zealand has, at infrequent intervals, collected sea level data in the Ross
Sea region of Antarctica since 1957. The best continuous sea level data sets are
15 months of data from Scott Base in 1988 to 1990. The Scott Base gauge, an
absolute pressure transducer type, was lost in a storm in February 1990. The
gauge is to be re-established as a permanent site in 1990 with a second gauge
to be established as a permanent site at Cape Roberts in 1991.

2.6 Recent and Applicable Meetings and Workshops

2.6.1 Workshop on Sea-Level Measurements in Hostile Conditions

10

This meeting was held at the Proudman Oceanographic Laboratory, Bidston
Observatory in Bidston, U.K. on March 28-31, 1988. The workshop ended with
the participants agreeing on the following general conclusions:

e The technology needed to make sea level measurements in hostile
regions exists and is affordable;

e the technology and techniques used must be site specific;

e bench mark connections are mandatory using the applicable state-of-
the-art technology;

e atmospheric pressure measurements are mandatory using the ap-
plicable state-of-the-art technology;

e real-time data transmission is required to ensure proper operation and
early availability of data to the user community;

e since the availability of global reference systems (Very Long Baseline
Interferometry [VLBI] and Global Positioning System [GPS]) has in-
creased, the local reference system can be connected to them and
subsequently the sea level data measured in relation to the latter will
become extremely valuable;

e bench marks themselves have to meet the technical requirements for
the site in view of permafrost disturbances and other local hazards.

2.6.2 First Session of IOC Group of Experts on the Global Sea-Level Observing
System (GLOSS)

This meeting was also held at the Proudman Oceanographic Laboratory,
Bidston Observatory in Bidston, U.K. in June 19-23, 1989. The Group discussed
the draft report of the Committee on Geodetic Fixing of Tide Gauge Bench Marks
(TGBMs) set up by the IAPSO Commission on Mean Sea-Level and Tides. The
Group supported the recommendations, technical conclusions and strategy in
the report. In particular, it was agreed that the primary strategy of connecting
GLOSS (and other) tide gauges with differential GPS measurements to the
fundamental VLBI/ Satellite Laser Ranging (SLR) stations of the conventional
terrestrial reference frame (of the International Earth Rotation Service [IERS]) was
very important for the various oceanographic and geophysical requirements listed
in the report. Wherever possible, the vertical movements of the TGBMs should
be verified by absolute gravity measurements.

11

The Group discussed the five technical conclusions of the Committee’s draft
report and made the following recommendations:

e ‘It is recommended that all gauges used to monitor mean sea-level must
have a local network of bench marks (6 to 10) that are resurveyed by
accurate levelling or GPS at least once per year and that information on
this local bench mark control should be collected by the Permanent
Service for Mean Sea Level (PSMSL).

e Using the accuracy of differential GPS stated in the report (1 cm in 1000
km) and the positions of the IERS (VLBI/SLR), it is possible to identify
those GLOSS gauges that can be fixed to within 1 cm radially with
respect to the IERS stations. It is recommended that the GLOSS gauges
within this range and with, for example, (a) 20 years mean sea-level data
and (b) 60 years mean sea-level data be identified and priority be given
to geocentric location of these gauges.

elt is recommended that GLOSS gauges that have 60 years mean
sea-level data, and where no IERS station is within 1000 km, should be
identified as priority locations for either permanent VLBI/SLR stations or
for mobile VLBI/SLR measurements.

e It is recommended that present IERS stations with no suitable GLOSS
gauges within 1000 km should be identified and consideration should
be given to installing suitable tide gauges within this range.

e It is recommended that the PSMSL would be a suitable center to collect, -
archive and distribute the geodetic information for each TGBM and that
the PSMSL should consult the IERS Directing Board with regard to the
information defining the geodetic reference frame that needs to be
stored."

2.6.3 Workshop on Sea Level Measurements in Antarctica

This meeting was held in Leningrad, USSR in May 28-31, 1990. The par-
ticipants at this workshop reported the following specific problems facing in-
stallers of reliable tide gauges in the Antarctic region:

e Ice scouring on the near-shore sea bed;
e the destruction of support structures by sea ice;
e the logistics of gauge maintenance;

e the lack of ice free locations and/or the unknown spurious effects
encountered when using a gauge with a heated stilling well;

12

e the power requirements necessitated by any mechanism including
automated data uplink to a satellite.

The Group’s review of the gauges currently in operation revealed that one was
a conventional float gauge (using a heated stilling well), one was a bubbler gauge
and four were absolute pressure gauges.

The consensus of the participants was that the most appropriate type of gauge
for Antarctic conditions was a bottom-mounted absolute pressure gauge, both
recessed into the sea floor and with cabling either recessed into the local rock or
well protected by some other means from ice action. The Group also agreed that
gauges must be calibrated on an annual basis at ice free periods.

2.6.4 Second Session of the |OC Group of Experts on the Global Sea-Level
Observing System (GLOSS)

This meeting will be held in Miami, FL, USA in October, 1990.

2.7 Organizations Interested in the Polar Regions

Organization Country Contact Person
NOAA/NOS USA L.Baer
301-443-8938
National Science Foundation USA T. Delaca
Div. of Polar Programs 202-357-7894
IOC France V. Jivago
Ocean Services Unit 33-1-45-68-40-44
Canadian Hydrographic Service Canada G.M. Yeaton
Tides,Currents, Water Levels
Flinders University Australia G.W. Lennon
School of Earth Sciences 08-275.2298
Inst. of Oceanographic Sciences U.K. D.T. Pugh

042879-4141

13

U. of Hawaii USA K. Wyrtki

Dept. of Oceanography 808-948-7633
Arctic/Antarctic Res. Inst. USSR V. Ivchenko
Comm. for Hydrometeorology 352-03-19
Dept. of Survey/Land Info NZ: J. Hannah
New Zealand 64-4-710-380
Hydrographic Dept. Japan M. Odamaki
Maritime Safety Agency 81-3-541-3811
Army Corps of Engineers USA J. Brown
Cold Regions Res.& Eng. Lab

Off. of Naval Research USA T. Curtin
Arctic R & D 703-696-4118
U. of Alaska USA D. Kowalik
Modelling 907-474-7753

3.0 WHAT NOAA/NOS COULD DO IN THE NEAR-TERM

NOS is presently performing two projects to improve measurements in the
Arctic region. The first is the establishment of a year-round tide station on the
north slope of Alaska. The second is the testing and evaluation of a new type
bench mark resistant to frost heave.

3.1 Prudhoe Bay Saltwater Treatment Plant

The establishment of a long-term, year-round, tide station, using NGWLMS
technology, at the ARCO Saltwater Treatment Plant (STP) in Prudhoe Bay was
accomplished in July 1990. This station will replace the seasonal Prudhoe Bay
station located about 1.6 Km away on the same gravel causeway known as West
Dock. A year-round station at the STP is possible only through the unique
circumstances associated with the STP design. The ARCO STP is a massive
barge sunk in-place at the end of West Dock. It is surrounded on three sides by
gravel, with the fourth side fronting onto a small, sheltered, bay. The STP is used
to process seawater before it is pumped underground to facilitate oil removal.
Two bubbler gages were installed at the STP in August of 1988. The instruments

were located inside the reservoir room at the southern end of the barge, which
is where the large water intakes are located. One orifice was installed outside the
barge (on a pile), and the other was installed inside the barge, just inside one of
the large intakes to the western reservoir. See Figure 10.

The purpose of two gages was to determine whether or not the water level in
the western reservoir truly reflected the outside water level, so that it might provide
a protected environment for the establishment of a permanent station using
standard equipment. It was initially thought that the outside orifice would not
survive the severe winter conditions.

After a year of operation, tidal analysts of the Physical Oceanography Division
determined that the inside water level does accurately reflect the true outside
water level. In addition the outside orifice survived the winter conditions so well
that it is now believed that an outside orifice can be permanently maintained. In
July, 1990, a full NGWLMS was installed inside the STP. In addition, the outside
orifice is being used, and a digital bubbler gauge, using a high precision
Paroscientific pressure sensor, is measuring the pressure variation in the gas-
purged tubing. This station is the United States’ first permanent year-round tide
station north of the Aleutians!

Future projects in this area could be the establishment of other stations, on
facilities like the Arco STP if they exist at other oil fields, or on some of the oil
companies’ artificial islands. Investigations should be conducted to determine
the number and locations of these types of facilities and analyses made of their
suitability as strategic GLOSS stations.

3.2 Thermal Bench Marks

A new type of bench mark was developed inhouse through the application of
existing technology. It is being tested for use in remote areas where no bedrock
or permafrost exists, and Class A type bench marks are too difficult or expensive
to install. The new type bench mark, called a thermopile or "thermo" bench mark,
is a type of bench mark specifically designed to resist the frost heave (vertical)
forces generated by seasonal freeze/thaw cycles, specifically in Arctic regions.
The thermo bench mark operates on a heat transfer mechanism and is generically
known as a two-phase closed thermosyphon. Ten foot of a 1-inch diameter iron
pipe is sealed and pressurized to 600 psi with carbon dioxide gas. The process

15

is activated only when the air temperature is colder than the ground temperature.
The temperature differential can be as small as one degree. The temperature
differential starts an evaporation /condensation cycle within the pipe. The material
within the pipe is in both a liquid and gas state due to being charged with a
refrigerant. Heat is absorbed from the ground through evaporation of the liquid
which rises to the top of the pipe. The rising gas meets the colder air temperature
and condenses, radiating heat out from the upper half foot of pipe. Gravity pulls
the condensate back down the pipe to the bottom and starts the cycle over again.
This cycle tends to keep the thermopile at a uniform temperature over its entire
length. This will reduce the thermal expansion /contraction effects and result in
freezing occurring radially about the thermopile. Ice lenses and other associated
pressures will develop radially and therefore not in the vertical direction necessary
to cause heaving. See Figure 11.

Three thermo bench marks were installed in Port Moller in 1987 to supplement
five standard Class B deep-rod bench marks installed in 1984. Three of the Class
B deep-rod marks are steadily being jacked out of the ground by frost heave. To
date, after three years of seasonal freeze and thaw, the three thermo bench marks
have not shown any movement.

It is recommended that thermo bench marks be incorporated into NOS’
accepted bench mark types and be used at remote sites with suitable conditions,
where appropriate.

4.0 CONCLUSIONS AND RECOMMENDATIONS
4.1 Conclusions

The conclusions of this report are essentially the same conclusions reached
by the various workshops held on making water level measurements in polar
regions. The problems are associated with ice scouring on the near-shore sea
bed, the destruction of support structures by sea ice, the logistics of gauge
installation and maintenance, the lack of ice free locations, and the necessary
power requirements of the site. But, on the other hand, it appears that these
problems are not insurmountable and, with proper planning and resources, are
definitely solvable. The consensus of the experts is that the technology needed
to make sea level measurements in polar regions exists today and is considered
affordable. However, the technology needed and the techniques used for

16

installation and maintenance are quite site specific and therefore no standard
"manual" can be written at this time. Bench mark connections and atmospheric
measurements made in conjunction with underwater pressure sensors are con-
sidered mandatory using the applicable state-of-the-art technology for the site.
Near real-time data transmission is highly desirable to ensure proper operation
of the station equipment and early availability of the data to the user community.
Also desirable is to make the field measurement system as automated as possible
and to connect the local measurement and reference system to the VLBI and
GPS global reference systems, if available.

4.2 Recommendations for Future Study and Work

The United States (and therefore NOAA/NOS) appears to have fallen behind
the other countries of the world in making water level measurements in hostile
environments and in particular the polar regions. The following general and
specific recommendations are made relating to future efforts that NOS should
continue or commence to ensure its world leadership in the area of water level
measurements.

4.2.1 | tion

- Continue to actively support NOAA’s Climate and Global Change Program
and the Intergovernmental Oceanographic Commission (IOC) GLOSS Program.
These two programs provide the network of international experts and hopefully
resources to obtain world-wide high quality standardized data from which valu-
able sea level products will be obtained.

- Establish near and long-term objectives and goals for NOS for making
measurements in polar regions. A committee consisting of a subset of the
managers involved in the Climate and Global Change Program should prepare
such a list of goals and objectives for NOS over the next ten years initially and
then beyond.

- Foster development of advanced technology through the DOC Small Busi-
ness Innovation Research (SBIR) Program and others means such as grants,
contracts and visiting research scientists/engineers.

17

- Establish cooperative programs with other agencies (NSF, COE, NASA,
etc.), universities and foreign governments. The National Science Foundation is
very interested in polar research and funds many projects in Antarctica but its
mission prevents it from funding monitoring programs. It appears feasible that a
cooperative program could exist between NSF and NOAA whereby NSF funds
the initial research portion of a water level measurement project in the Antarctic
and then NOAA would continue the funding when the project becomes more
routine. A similar type of arrangement could be made with the U.S. Army’s Cold
Regions Research and Engineering Laboratory or with NASA. We already have
cooperative projects in progress with the Canadians, British, Australians, and
Russians and should expand them to include field measurements in polar regions.
NOS should also develop projects with Japan and New Zealand.

4.2.2 Specific Recommendations

- Investigate and find additional suitable sites for polar tide stations such as
the one established at the Prudhoe Bay, AK Saltwater Treatment Plant. After
suitable sites are found, they should be prioritized and an installation schedule
generated. The Prudhoe Bay site should be established as a pilot station for
continued R&D activities.

- Continue to refine techniques for the installation of thermal bench marks at
appropriate cold region sites. These types of bench marks have been proven
very successful in areas where an active zone exists on top of the permafrost
layer.

- Continue and foster the development of acoustic and electromagnetic links
for the transmission of information through the water/ice interface. A few
American companies have developed prototype underwater acoustic modems
with much improved reliability and data rates. A Canadian company has
developed a prototype electromagnetic device for transmitting data from sensors
under the water to aland-based receiver. Both of these developments show great
promise as the communication links of the future.

18

uoibey dndJy oUL “| eunbi4

\
\
Z

\
pivs! N
Yi VINOLIIAN
\

~~ ee

SS \

GNVIS! Nibjve

/

| 3u3WS3103

kes GNV1N3349 l

/ < NK \ x
SS ~
/ i

vist

7 ‘ouiova

ONV 1Si.

vusSVIV 40 »v ION

VASVIV

| syunquiny &

vas d
IHOMNHO
WS

°
M0408 Id

vas

inosnvag ONvas| if
/ V139NVeM

~
x

vas

a

370d HLXON

BL/b ONSDIY 40 BOY jO;UaWUOsIAUG

HLYON

SONV1S!
NvILN3dv

\

w
Nwuaais, \ %

SESSBJODON|OD

ueed0C UP/pUl

uoibey onouejuy eUuL “Zz eunbi4

ueedO JyJ9ed YyINOS

Ud}}JEIS
OPpJNIWOW

uOone}S
SOMIIM

uonels
pkg
@

UONEIS E10d YyINOS Aue
yj09S-uespunwiy &
=

udHeIS
neejeid jloUuS 99]
e JOUUd|!4

VOILOYUVLNV

uoney
YYOms||

eouesjUuy
euuoYy ees

IlEPPEM

uee90 ORUeNY YyINOS

yweus 09] [J

SUOI}E]S PUNOI-1EBA JOWIO4

suonelg punol-see, yueLND @

Aeg
ewenbiew

peseg se

> UO}eIS JOWIed
spue|s|

20

eySE|Y Ul SUONLIS SPILL SON “€ eNbi4

A) (5)
aa ° G oWQ 2
nyo e “a wvGV & S G
Reese lowyNG
VYSV TV 4O FIND INIOd GNVS ~¢ F
3 a Ava TOLSIYE a
po (ys Oo w
S 9 NVAIHD i yvIGO ue , y
ges . MALIS wIAOG1as Ya suojyeis Epil jeuosees HH
= Mk ae ; & suones eplL SON Bursa @
nvannr~ \ YAHSIMIN : Sy
AYMOWAS Sioa / FDVHOHONY
VAOGHOO GNNOS
— NOLYON MS _
\ a
; ‘wsn 1 9S
vavNVo \ WISVIV Nos y
: ‘us’s'n
AVa SOHGNYd VAS IHOMNHD
Dp
VAS LYOF
O4NVAg MG \

SNOILVLS AGIL SON

21

wa}sAs uolsinboy e}eq yUueseld “py einbi
SNVLNI 39141a0

35141d0 a3 dan TW13M ONIVIVULS

f

UNS)

ONT Wd

Vall
NOILVOI4ILvaLS ~~
ALISN3d ~7—~

TAA41 SaLVA NVSW LNATEWy
S3AVA

V1S9M JSCISNI 13A31

MGLVM SNO3NVINVISNI =

N SS
ddId

ONIGNL 83 adn

ivO4 MaVW HONIG
3aIM LvO14 SqSV SSS Orel
Oi
39V9 af 1ddnd 39v9 wav

3SMOH Adit

22

|
:
|
|

JUN Reka) <==

1
el
=

\

\

\

|

|
ee ea a
mal |[l/M0

Vall
NOLLVOI4ILvalS ~~
ALISN30. 77

wia}shs }UsWSINSeS|] [BAD] 18}eM\ UOILIOUSH 1XON ‘SG ounbi4

YOSN3S

JSYNSS3dd oN

aS

TAA371 YaLVA NVSAW LN3IEWy
SSAVA

V1SM 3CISNI 143A31
SALVA SNOANVINGLSNI

Fant |

ONIGNNOS/NOI LV 1Vv9
V1I3M 3ATLO39L0¢d

) N
oS
=

/

YOSN3S JILSNODV

WdO4LV 1d
NOILO3ST1IO9 Vivd AYVAIdd

= SZ
ad3lId

MaVW HONIE

4AVLS HLIM ADEW3ASSY¥
ddvOd ONINOVA YOSNIS

WYO4LV 1d NOWDITIOD VLIVG dNyXOVva

YNNJINY $309 NG

SSNOH 3dIL

23

Oq
ainssaid
89110

39140
sajqqng

d
Ayisuap
Jayem

eq
ainssaid
oueydsowjye

Buigny
auajAujaAjod
wh X

POO ION ors
yoRY 9d}

"

uonelje}sul UOIBeY 1ej0d a|qISSOd “9 einbi4

H6d =
ey = 04 =
wd eainssaid a6e6 painseaw

(dOG 0006 SAIMON)
Wu0}}e|d UONDA||O9 eyep «
(dyUaldsoseq)
Jaonpsued) ainssaid «
yun jOujU09 MO} SEB «
JapuljAo se6 passaidwoo «

uoNeIS
JOA97 JOVEN

ix YN Y)

Ie
youag

24

hs - Stabilization [_]

|
!
|
Upper Level & | ! /. AccessDoor 1 |
Instrument | ! Let ae
Access Door! a Vo
| I 14
I |

— Electrical Fuse &
Junction Box

Steel Structure With
2" Styrofoam Insulation

Wood Structure With
ih 2" Styrofoam insulation

Lower structure slides

up & down around outside
of upper structure as the
tide comes in and goes out

If
al
\
Diesel Stove
| Fuel Barrel
Bubbler

—
~~ Tube
A

ZED 18"x30"x48" Submerged Tank
With Fuel Fire Stove Inside

Heat Tape On ——
All 3 Legs

au ai
“ /

7" Round Steel Pipe With
Fiberglass Liner For
Stilling Well

Figure 7. Dinkum Sands Project Tide Station Installation

25

3 ARCTIC BAROMETER/
Roe. ARGOS PLATFORM

Se ees (Fa

—)

SOLB.WEIGHT -

The atmospheric pressure-measuring system operating in situ with the satellite uplink, the
electromagnetic (EM) link, and the submerged tide gauge. FEBRUARY 1990/SEA TECHNOLOGY

Figure 8. Canadian Developments

26

uoneIS VMOAS eseueder ay} je UOHeAJOSQO jepl) jo Wa}SAs juaseld ey “6 aunbi4
YOHONV

JANL ONILIFLO"d

JONVS AGI

391 vas 49) 1SV4

Adid NOU! MYVW HONS

‘aV7 3ONSIOS HLYW3 (HaW3H W HLIM)

XOd LNIOF

x V7 V7/

LNH NOILVAYAS8O J4GIL

NOILONYLSNOO Y3AGNN
WALSAS NOISSINSNVHYL VLVG

27

SEAWATER
TREATMENT
PLANT

Coraver

----—) _ WESTERN RESERVOIR
oan (inside NGLWMS location)
i]
\
!

INTAKE #1

z SOLITARY PILE

(Outside onitice location)

CIRCULAR CELL SHEET PILE BULKHEAD

(Geena SEAWATER

RESERVO! TREATMENT ‘UwesterN RESERVOIR
PLANT 7

FISH DIVERTER SCREEN

NGWLMS DCP LOCATION \

INSULATED WALL

Figure 10. Prudhoe Bay, Alaska, NGWLMS Site Sketch

28

3° DIA. ALUMINUM DISK
WITH THREADED STUD

FALL: The active layer starts
freezing from the top and
Proceeds down. Ice lenses
form creating heave forces in
upward direction. The thermo
bench mark is activated by the
air temperature dropping below
ground temperature. The
refngerant is heated to the
boiling point by the higher
ground temperature along the
bottom of the mark, and
evaporates to the top, where it
condenses. The condensate
then retums to the bottom of
the mark through gravity. This
thermal cycling draws heat out
of the ground radially around
the thermo bench mark. The
radial freezing prevents ice
lense formation adjacent to the
mark and therefore upward
heaving forces. Higher
temperatures near the top of
the mark also cause the frozen
soil to sublimate and relax its
grip on the mark.

ACTIVE LAYER

WINTER: The active layer is
completely frozen and the
potential for frost heave is past.
The thermo bench mark
continues to cycle and reduce
the grip of the frozen soil near
the surface.

SPRING/SUMMER: Air
temperature is greater than
ground temperature and the
thermo bench marks thermal
cycling stops. No heave forces
are present during these
seasons.

1° DIA. EPOXY COATED
PIPE FILLED WITH
PRESSURIZED CO, GAS.

REFRIGERANT FLUID

PERMAFROST:

DRIVING HEAD WITH
THREADED STUD

%
HEAT FLOW = = —>> EVAPORATION QU? CONDENSATION

Figure 11. Thermo Bench Mark

29

' et teh ma am sf

Se ee ee a

k acuavent Wp
wee nataal | (CRE

- et en ae a op { jue

i, a, TERRI AA RII

j 1 tie ee Pein s pierre aie
[ 4 4 a a PEaTARO ANS | Bes ns
; ) (i seen meacie ‘ “ 1 yur meen om Negus ear ers ata shes Ay ea 4 Pe / earners jn ‘sree MERRY OY
ars: ~parrnedricr: Phy err tetas Sb ooo
Liha a reno commnedt?

APPENDIX A

REFERENCES

Aagaard, K. et al. Outer Continental Shelf Environmental Assessment Program
(OCSEAP) Final Reports of Principal Investigators. NOAA/NOS/OMA. Vol. 65.
January, 1990.

Brochure of Artic Foundations, Inc., Anchorage, AK. Erozen Assets. Erwin
L.Long, President. 1983.

Global Sea-Level Observing System (GLOSS) Implementation Plan. Fifteenth
Session of the IOC Assembly. (IOC-XV/8 Annex 4) Paris, 4-19 July 1989.

Hartman,C.W., and P.R. Johnson. Environmental Atlas of Alaska. University of
Alaska. Revised 1984.

Report of First Session of IOC Group of Experts on the Global Sea-Level
Observing System (GLOSS). Proudman Oceanographic Laboratory, Bidston,
U.K., 19-23 June 1989.

Russin, E.M., T.N. Mero, and S.K. Gill. NOAA’s Water Level Measurement System

for the Nineties and Beyond. Conference Proceedings. Marine Instrumentation
90 Exposition and Conference. pp 52-56. February, 1990.

Schwerdtfeger, W. Weather and Climate of the Antarctic. Elsevier, NY, 1984.

Shih, H.H. Pneumatic Tide Gauge Upgrade. NOAA Technical Memorandum, NOS
OMA46. 1989.

Smith, T.E. Atmospheric Barometer Measures Sea Surface Height. Sea Technol-
ogy. February, 1990.

Steeves, G., Bedford Institute of Oceanography, Nova Scotia, Canada, personal
communication, May 31, 1990.

Weller, G. and S.A. Bowling, Editors. Climate of the Artic. 24th Alaska Science
Conference. University of Alaska. 1973.

Workshop on Sea-Level Measurements in Antarctica. |OC Workshop, Draft
Report, Leningrad, USSR, 28-31 May 1990.

Workshop on Sea-Level Measurements in Hostile Conditions. |OC Workshop
Report No. 54. Bidston, U.K., 28-31 March 1988.

Wrathall, P., Correpro Atlantic, Ltd., Nova Scotia, Canada, personal communica-
tion, August 13, 1990.

Al

7 i. inet, Godateeln ma 4 (2BOIE)
hia be ake ene at ei |

lowe see twice ert No ohn So thoi) BOI: to. adlbeee he 1B nx
nS wicca aioanee pate TINCEON — evade 2G
Panu. oS

v
“A

deade elivaeteaanolh lwo. vesete \C) fi) 12 borne: Sule Wy, Me,
} CRaESIT AT RRO rs edie poet booved Gig Bdito-w
ee OR Apne HIF B-S8 a6 é rave oS) bike alia

r etiiecsiie baiprtog ¥ DAC 1 para a mote oy

Ve Sau ond ingle ecnathue eed era solace wel srengaerth ay if
7 ie | DY Vicia 2, sense) stone mA rinigonaieD to atnitend Gebea a: ‘ }
ee yh ee \Oe8er AE yeni “suena
Ve 7 | SORSIOE aout HOR) oi wit MO eternite CMe ad siwoel M2 bn Qo soo a
Hie. — uF 4 ‘e¢Rt Ba > yttenevic) aT ter
ee tend, aoe arta SOI .acitoeinA nl aindmanamal levetee? ng eprania! a
a ane | IGT at TEAMS |G a bengine Hoge” a
“| 7 : ' ore AON DOr’. srieithis rich oy olite of 6 | ee | wr eyatioM ‘aves age OQ, 0 jorholly y
, | BBRE rave TEAR YALU inorebid ae on nogeH
a slog 9) has rowieq as plows of ivOM, te dl oat orev a waco ig

bee? et ie tt

APPENDIX B

SELECTED BIBLIOGRAPHY

Antarctic Oceanography. Proceedings of Symposium. Santiago, Chile.
SCAR/SCOR/IAPO/IUBS. 1966.

Barnes, P.W.,D.M. Schell, and E. Reimnitz. Editors. The Alaska Beaufort Sea
Ecosystems and Environments. 1984.

Coachman, L.K., K. Aagaard, and R.B. Tripp. Editors. Bering Strait, The Regional
Physical Oceanography. 1975.

Murphy, T.K.S., J.J. Connor, and C.A. Brebbia. Editors. Ice Technology.
Springer-Verlag, New York. 1986.

Rey, L. Editor. The Arctic Ocean. John Wiley and Sons. New York. 1982.

Bi

},

oe

, ; Panes ait
v 4 1! 4] . fd
i ; Aaa” BAe
: ( a ; nes oe An
shy Ane : eR aS Aes)

On iy
STA

Acknowledgement

The authors would like to thank Patricia Bass for her assistance in the areas
of graphics and desk top publishing.

wi

ily ne bb |