Eddy correlation measurements of evaporation and sensible heat flux over Arctic Sea ice

Abstract

A sonic anemometer, lyman alpha humidiometer, and thermistor thermometer were operated on ice at 75°N, 15°W in March-April 1972 as part of the Aidjex pilot study. Spectra of temperature and humidity fluctuations and cospectra for the sensible and latent heat fluxes were similar to those published for neutral conditions over sea and land. Bulk transfer coefficients were CT = 1.2 × 10−3 and CQ = 0.55 × 10−3, respectively. The Bowen ratio of sensible to latent heat fluxes ranged from 1 to 15 and can be obtained from values of the temperature and humidity spectra at low frequencies except when the latent heat flux is very small. These data were recorded at the spring equinox, and the dominant feature of the heat fluxes is their diurnal variation. Evaporation continued for several hours after the sensible heat flux changed to the downward direction. Over Robeson Channel in July 1972 the heat transfer coefficient was CT = 1.0 × 10−3 for stable conditions.