Radiative energy budget in the cloudy and hazy arctic

Abstract

A radiation model is constructed that includes radiative interactions with atmospheric gases, as well as parameterized treatments of scattering and absorption/emission by cloud droplets and haze particles. During the arctic summer, stratus clouds are a persistent feature and decrease the downward flux at the surface by about 130-200 W m-2. Arctic haze in the summertime is important if it is above the cloud layer or in air with low relative humidity, and it decreases the downward flux at the surface by about 10-12 W m-2. By comparison the greenhouse effect of doubling the carbon dioxide amount increases the downward flux at the surface by about 4-7 W m-2 and can be offset by the background haze or by an increase in cloudiness of about 4%. Assuming steady microstructures of stratus clouds, we find that in late June a clear sky condition results in more available downward flux for snow melt (yielding a melting rate of 9.3 cm day-1) than does a cloudy sky condition (6 cm day-1). -Authors