72 M. C. Miller et al. 



data of P. Miller (personal communication), or from the NOAA weather 

 station at Barrow. 



The winds are remarkably constant during the summer months 

 (Table 3-13) and vary little from month to month or from year to year. 

 However, the NOAA data are taken at 9 m above the ground and there is 

 a logarithmic decrease of average wind speed towards the ground. For 

 example, the summer 1971 IBP data (Weller and Holmgren 1974) show 

 that the average wind speed at 0.25 m above the ground was only 44% of 

 the speed at 8 m. The emergent grasses and sedges around and in the ponds 

 reduce the wind speed even further but we have no measurements of the 

 speed of the wind that contacts the water surface. 



There was no significant correlation between the wind speed and the 

 current velocities during six of the eight diurnal measurements. Of course 

 the currents did increase during high winds, but evidently our measuring 

 devices were not sensitive enough to give the complete picture. On the two 

 runs showing significant correlation, 18 and 19 July 1973, the currents 

 were measured 1.5 cm below the surface while the wind speeds were from 

 the NOAA Station at Barrow. On these dates (Figure 3-9), the current 

 velocity was 0.07 to 0.12% of wind speed at 9 m, which is much less than 

 the 2% of wind speed expected for currents in lakes (Hutchinson 1957). 

 Over the 8 days of measurement, the currents ranged from to 1.2 cm 

 sec ' while the winds ranged from 102 to 1028 cm sec '. 



On five of the diurnal studies the surface currents of the pond dropped 

 to zero during the night even though there was continuous wind at 9 m 

 (Figure 3-9, 19 July). This is likely caused by an inversion or similar 

 abrupt temperature change of the air immediately above the water. 



The surface currents produced by the wind move water to the leeward 

 side but there is also a return current along the bottom. These wind 

 currents, along with the microturbulences set up along the shear zones and 

 the circulation produced by sediment heating, are extremely important in 

 resuspending detritus and bacteria from the sediments and in keeping the 

 benthic sediments and water well oxygenated. 



SUMMARY 



The IBP study ponds lie in an area of polygonal ground. Each pond 

 averages about 20 cm deep and has a maximum depth of 40 cm. At the 

 beginning of the summer the whole polygon may be flooded; after a dry 

 summer only the central depression will retain water. 



Erosion and reworking of sediments make '^C dating unreliable in 

 the pond sediments. A peat layer beneath the oldest lake sediments is 

 12,000 years old. Several lakes formed and drained at this site but the 

 ponds lie in a lake basin that likely formed 3,000 to 6,000 years ago. Thus, 

 the ponds are likely several thousand years old. 



