The Relative Importance of Clouds and Sea Ice for the Solar Energy Budget of the Southern Ocean (original) (raw)
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The analysis of measurements of daily mean temperature, daily mean relative humidity and daily total solar irradiation for the period 1979-1985, at the Antarctic stations Almirante Brown (64.9oS, 62.9oW, 10m a.s.l., West of Antarctic Peninsula), and BelgranoII (77.9oS, 34.6oW, 250m a.s.l., East of Antarctic Peninsula) is presented. A short-term characterization of monthly averages was established. Typical temperatures for summer and winter were 2oC and –7oC respectively at Brown, and –2oC and –20oC at BelgranoII. Relative humidity was always above 60% at both stations. Both measured parameters enter also as input variables in model calculations of the equivalent clear-sky daily total irradiation for each day, to determine the effective cloud transmittance of solar radiation. The effect of cloudiness was stronger at Brown, where an average cloud transmittance of 49% was determined, while it was of 71% at BelgranoII. Average daily irradiation of 27.4MJ/m 2 in December at BelgranoII is...
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The surface radiation environment over the Southern Ocean within the region bound by 42.8° S to 78.7° S and 62.6° E to 157.7° W is summarised for three austral summers. This is done using ship-based measurements with the combination of downwelling radiation sensors and a cloud imager. We focus on characterising the cloud radiative effect (CRE) under a variety of conditions, comparing observations in the open ocean with those in the sea ice zone. For comparison with our observed data, we obtained surface data from the European Centre for Medium-Range Weather Forecasts fifth reanalysis (ERA5). We found that the daily average cloud fraction was slightly lower in ERA5 compared with the observations (0.71 and 0.75, respectively). ERA5 also showed positive biases in the shortwave radiation effect and a negative bias in the longwave radiation effect. The observed mean surface CRE of −164 ± 100 Wm−2 was more negative than the mean surface CRE for ERA5 of −101 W m−2.