Physics 57 



The highest temperatures and greatest diel ranges occur on sunny 

 days when changes of 8°C are common but changes of 10° are rare (Figure 

 3-4). In this figure, the depression of both range and magnitude in late 

 August is due to snowdrifts in the pond following a snowstorm on 19 

 August. The highest temperature recorded during 4 years of study was 

 20°C in Pond B on 6 July 1972. 



The temperature regimes in other tundra ponds appear similar to that 

 of the IBP ponds. Kalff (1965) observed a high of 19.9°C in his Pond II on 

 16 July 1964. Cameron et al. (1973) recorded 22°C in flooded shallows 

 behind the beach berm at Ikroavik Lake on 6 July 1972, the same day as 

 the maximum in Pond B. Ponds from other arctic areas such as Cape 

 Thompson (Watson et al. 1966a) and Bathurst Island (Danks 1971a) have 

 similar temperature patterns. 



The same pattern does not hold for lakes, however, which are similar 

 to temperate lakes with a very small diel temperature range and a 

 maximum temperature in August (data summarized in Hobbie 1973). In 

 one direct comparison between a Barrow pond and a nearby shallow lake, 

 Stross and Kangas (1969) found that pond temperatures averaged 10°C 

 higher than lake temperatures (15 June to 15 July 1967). 



Sediment Temperatures 



Temperatures at various depths in the sediments were recorded 

 hourly in Pond C in 1971 (2 cm depth using thermocouples), and in Ponds 

 B (1972) and C (1973) at and 10 cm depth using a YSI scanning tele- 

 thermometer (data reported in Stanley 1974, 1976a). 



The average temperatures at the surface of the sediment are very 

 close to the average water temperature. For example, betwen 14 June and 

 27 August 1972 the water temperature averaged 8.4°C and the sediment 

 temperature 8.5°C (Table 3-3). However, on sunny days the sediment 

 temperatures can be 2° to 4°C above the water temperatures. This rise was 

 relatively brief and as the sediments warm more slowly than the water in 



TABLE 3-3 Mean Water and Sediment Temperatures, 1971 and 1972 



Water Sediment 



cm 2 cm 10 cm 



4.5 



5.2 



1.5 



