a chart of stability indeXe 



5«. Effect of Tlue of Cbsorvation Upon the Ice Potential 



Before discussinp; the ice potential climatology of the Beaufor.t 

 Sea in detail, it is necessary to consider the effect on the cl ima to lo ?;;;;'■ 

 of the tirae of the oceanographic data collectiono Since the ice po,t.ential 

 reflects the actual heat content and stability of the water mass at-^tbe 

 tine water samples ai'e col].ected, it is depjendent on the heat budget of 

 the watero If the potential ice thickness is calculated at intervals 

 while the water is ,r];aininp; heatj the sensible heat loss necessary to 

 form a specified amount of ice will increase » Conversely, during the 

 tirae when the water is losing heat, the potential ice thickness wi]l.l 

 steadily increa.seo The time of reversal of the heat budget in the 

 Beaufort Sea is not kno>m with certaintyo Separation of the available 

 data into those secured before and after 31 August did not show any 

 noticea,ble tine differences on an area-wide scale, although in some 

 individual cases where oceanographic stations were repeated at in- 

 tervals of a month or more, there was considerable variation in the 

 potential ice thickness « 



G» ICE POTENTIAL GLIMA,TOLOGI OF THE BFAWtHT. SEA kW ADJACENT' WATERS 



The Beaufort Sea area has been selected to illustrate the use of 

 the ice potential cliraatological techniques described above. This area 

 has been one of the least known water areas of the world, but >rithin 

 the past few yeax-s the area has been extensively surveyed. The large- 

 scale factors iniltencing the ice of the Beaufort Sea have been con- 

 sidered previously by the author (Gorton., 195^4)* 



Iff Ice Potential in 19^1 



Figure 1 shows the potential ice thickness associated with a 

 uniform heat loss of 20 kga cal./cra«2 jn summer 19^1, assuming that 

 observations were taken simultaneously at a time near the neutral point 

 between heat gain and heat loss in the water columno A small area near 

 Point Barrow shows a negative ice potential of some kO cm. At this 

 location a heat loss of 20 kgoCal./cm.'^ is not sufficient to form ice. 

 In an area north of Barter Island the potential ice thickness amounts 

 to 200 cm. 5 whereas the center of the polar basin shows potential ice 

 thicknesses greater than 220 cmo A second area of low ice potential 

 is found in the entrance to Amundsen Gulf, with increases to the 

 east and northwest of this center. 



There is a large subjective element in figure 1 in drawing lines 

 covering such a large area with comparatively sparse data. Since the 

 observations are made in water at least 50 m, in depth, the isolines 

 are estimated near shore. Also, since ice conditi.ons limit the opera- 

 tions of ships, the geographical coverage of the area is not uniform. 



-It- 



