Water Temperature: -2° C to + 20° C. 



Ice: Winter is 8 to 9 montlis 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 a minimum. Additional 

 design considerations include preparing for ice cover in the long winter time and 

 ice break-up and drifting during summer. 



