Physics 63 



TABLE 3-7 Precipitation at Barrow (30 year average) and 

 at Other Stations in Northern Alaska* 



♦Source: Allen and Weedfall 1966. 



emphasize again the importance of the drifting and of the microrehef of 

 the polygon ridges on the snow depth and on the volume of water available 

 for runoff. 



The precipitation during the summer is more important to the ponds 

 than the meltwater from the snowfall because it adds nutrients and organic 

 matter through leaching from the soils and vegetation. In addition, the 

 amount of summer rainfall determines the water level, and therefore, the 

 degree of biological effect of the shrinking pond volume. During the 1970 

 to 1973 period, the summer precipitation ranged from 1.7 to 13.2 cm of 

 water at the NOAA weather station at Barrow (Table 2-2), where the 50- 

 year mean is 6.7 cm. While there were some differences between the IBP 

 site and the NOAA station, they were not significant. 



About 50% of the total precipitation is received as snow at Barrow, 

 similar to the value for other arctic sites. Thus, at two stations in northern 

 Canada, the values were 53% (Devon Island, Cogley and McCann 1971) 

 and 54% (Resolute Bay, Cook 1960). In the Yukon Basin to the south of 

 Barrow, some 40% of the precipitation occurred as snow and at Fairbanks 

 only 33.3% of the total of 31. 3 cm fell as snow (Dingman 1971). 



The total precipitation at Barrow over the past 30 years is comparable 

 to that of other coastal sites in northern Alaska (Table 3-7) and also to 

 other arctic sites. 



RunofT 



In 1972 and 1973 the runoff of snowmelt water was measured at five 

 outlets from the IBP Pond Site (Figure 3-1). This was done somewhat 

 crudely in 1972 by measuring the cross-sectional area of the outlets and 

 timing the speed of a slug of fluorescent dye over a distance of 1 m or 

 more. In 1973 the small outlets were equipped with "V" notch weirs which 

 were calibrated by collecting all the flow for an interval. The large outlet 

 (weir 1) was fitted with a Parshall Flume early in the melt period and later 

 with a rectangular notch weir. 



