Application Of SRB And CERES In The Study Of Cloud Effect On Surface Solar Radiation In Xinjiang

Surface solar radiation provides energy directly and plays a decisive role in the thermal and statusof the circulation of the atmosphere and ocean which shapes the main characteristics of the earth'sclimate as well. The effect of cloud on surface solar radiation is very complex. The different macrophysical properties such as clouds, the cloud amout and other different micro physical properties ofclouds have different effects on the surface solar radiation.Using long-term radiation surface data product (Surface Radiation Budget) which was releasedby NASA WCRP/GEWEX (World Climate Research Program/Global Energy and Water CycleExperiment) and the data sets of the Clouds and the Earth's Radiant Energy System (CERES)-CERES Aqua MODIS Edition3A, the influence of cloud and surface solar radiation in xinjiangregion were analyzed. The main conclusions were as follows:(a) Surfer solar radiation were annually in the overall trend of decline after rising first.From Aprilto August the surfer solar radiation reached a peak of values, which were more than350W·m-2.Cloud shortwave radiation forcing had significant seasonal variation characteristics of coolingthroughout the year, which showed a trend of decrease after the enhancement overall. The values ofcloud shortwave radiation forcing which were from March to July in the spring and summer wereunder-100W·m-2. Clouds which were55.5%generally had a trend of decline after rising first. Itwas similar that clouds and cloud shortwave radiation forcing both had the peak in April andNovember. The increasing (decreasing) of clouds amouts enhanced (reduced) the cooling effect ofcloud shortwave radiation forcing and furtherly caused the decreasing (increasing) of surface solarradiation in spring and summer.Interannual variability of the surface solar radiation and cloud shortwave radiation forcing werethe same that high clouds had the most strongly extinction effect on surface solar radiation whilemiddle clouds were the opposite.(b)The values of mean ice water path for high clouds were mainly betwwen0and300g·m-2, however, the values for middle and low clouds were under200g·m-2. Clouds which had mean icewater path of0-50g·m-2had the least extinction effect on surface solar radiation. Low clouds whichhad mean ice water path of100-200g·m-2as well as high clouds which had mean ice water path of1000-10000g·m-2had more strongly extinction effect on surface solar radiation than other valuesof which clouds. Middle clouds had slightly extinction effect on surface solar radiation with theexception of1000g·m-2-10000g·m-2. With the increase of mean ice water path, surface solarradiation and cooling effect of cloud shortwave radiation forcing of high, and low clouds were frommuch difference to the status that high clouds had a stronger extinction effect on surface solarradiation than the low clouds.(c) The surfer solar radiation basically increased gradually from south to north. Surfer solarradiation in mountain area decreased gradually for interface with mountains along the latitudeincreasing. The More close to the mountains contour the area was, the more intensive surfer solarradiation changed. The distribution of cloud shortwave radiation forcing enhanced from north tosouth and basically weakened from west to east which was except for the Kunlun Mountains. Cloudamount in Tarim basin area was the lowest which was between51%and41%, while the highest wasappeared in the Kunlun Mountains, which more than61%. Cloud amount in Tianshan Mountainswas between56%and51%, and clouds in northern mountain were more than that in the south.The spatial distribution of surface solar radiation in high and low clouds had the obvious changeprocess. Surface solar radiation of middle clouds in the xinjiang region was basically between100W·m-2-300W·m-2, in addition that the terrain and the latitude had less impact on spatial distributionof surface solar radiation in middle clouds. Two strong cloud shortwave radiation forcing effect areaappeared in Xinjiang which were junggar basin and eastern kunlun mountains and in both of thetwo areas cloud shortwave radiation forcing was under-300W·m-2. Middle clouds had moredamping effect on surface solar radiation than high and low clouds.(d) In four seasons cloud amount was negatively related to the surface solar radiation, howere,cloud shortwave radiation forcing is positive correlation.The correlation between cloud amount andthe surface solar radiation changed from month to month. In spring and summer the correlationbetween cloud amount and cloud shortwave radiation forcing changed slightly from month to month.The mean ice water path of high, middle and low clouds in four seasons had similar impact oncloud shortwave radiation forcing, and the influence of them and cloud shortwave radiation forcing was positive correlation. The correlation of mean ice water path in high clouds was higher than thatin middle and low clouds, and the pearson correlation coefficient was under0.5which reachedcorrelation of middle or high level.To compare with what in middle and low clouds, cloud shortwave radiation forcing can be betterexplained by the variance of mean ice water path in high clouds.