Untersuchen zum Strahlungshaushalt in der Akkumulationszone des grönlandischen Indlandeises.

Resumé

Study of the radiation balance in the accumulation area of the Greenland Ice Cap
(Carrefour Station, φ = 69°49'25"N, λ = 47°25'57"W, 1850 m)

The site of measurements is Carrefour Station (φ = 69°49'25"N, λ = 47°25'57"W, 1850 m) in the accumulation area of the Greenland Ice Cap. In general, the snow surface is dry, only during a few days in midsummer melting occurs without any run off. The radiation fluxes, incoming shortwave radiation, reflected shortwave radiation, incoming longwave radiation and outgoing longwave radiation were measured from 15 May to 27 July 1967 and were evaluated as hourly sums. The difference of the calibration factor for shortwave and longwave radiation as well as the dependence on the calibration factor from the solar elevation angle and the temperature were taken into account. Over the total period of measurements the albedo amounts to 84,9% referring to an undisturbed surface of the surrounding. The hourly variation of the albedo and the dependence on the albedo from the cloudiness are discussed. The averaged daily sums of the net radiation balance over the total period of measurements (74 days) amounts to 0.544 MJm ^-2d ^-1(13 calcm^-2d ^-1). In spite of high values of the incoming shortwave radiation, the net radiation balance is mainly controlled by the longwave radiation balance because of the high albedo. The sum of energy sources equals the sum of energy sinks within an error of measurement of 1%. The maximum value of the direct solar radiation, corrected for the mean solar distance, amounts to 60.71 kJm ^-2min ^-1 (1.45 calcm^-2min ^-1, 1012 Wm ^-2) at the solar elevation angle of 40.2° and an optical air mass of m=1.15.