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. 



