FY-2F云量产品在新疆区域的评估及检验

Evaluation of FY-2F satellite cloud products in Xinjiang

利用2015-06—2016-05月新疆区域地面观测的总云量小时数据,对比分析了FY-2F/CTA与地面观测云量的相关性和一致性,开展了FY-2F云量产品在新疆区域的分析检验。结果表明:(1)FY-2F/CTA与地面人工观测总云量的相关性较好,天山以北区域(含天山山区)冬季除外。(2)FY-2F/CTA与地面人工观测总云量的一致率为51.5%,南北疆差别不大,均是夏、秋季较高,但天山以北区域冬季较低,南疆春季较低;卫星反演总云量整体比地面观测值偏低,即呈高偏弱率低偏强率分布,南疆区域偏低最为明显。(3)不同云量等级下,一致率与总云量呈反比,即晴天、少云状况下的一致率较高,多云、阴天条件下的一致率较低。(4)沙尘会降低FY-2F/CTA判识的一致率,增大其偏弱率,但是对于有、无云的判识影响不大。本研究考虑了不同季节、不同云量等级以及有无沙尘影响,对FY-2F/CTA产品进行了评估,研究结果为干旱区总云量的卫星反演及应用提供了重要参考。

Clouds are an important element of weather and climate characteristics:they affect atmospheric movement and the earth’s climate through three mechanisms:radiative forcing,latent heat forcing,and convective forcing.Cloud is also an important parameter of artificial water augmentation,which is of substantial significance to judge precipitation capacity.Total cloud products from satellite observation are suitable for revealing large-scale climate characteristics,and they have advantages in the plateau,desert,ocean,and other areas where data are scarce.Xinjiang is part of the arid area of Northwest China,where weather stations are sparsely distributed and the types of underlying surface are complex.Therefore,it is suited to the use of total cloud cover products inversed from satellite.However,the retrieval of the amount total cloud from satellite data in arid areas with complex underlying surfaces is a challenging task.Based on the hourly data of total cloud cover observed by ground observation stations from June 2015 to May 2016,we compared and evaluated the correlation and consistency between the FY-2F/CTA products and manually observed total cloud cover in Xinjiang region.We found that FY-2F/CTA correlates with the total cloud cover observed on the ground,except in winter in the area north of Tianshan Mountains,including Tianshan Mountains.Additionally,the consistency rate of FY-2F/CTA products in Xinjiang region was 51.5%,and there was little difference in cloud cover among the three regions of Xinjiang,which is higher in summer and autumn but lower in winter in the northern of Tianshan Mountains and lower in spring in southern Xinjiang.The amount of total cloud inverted from satellite data was generally lower than that observed by ground observation stations,especially in southern Xinjiang.Under different cloud cover levels,the consistency rate was inversely proportional to the total cloud cover:the consistency rate was higher under sunny and partly cloudy conditions and lower under cloudy and overcast conditions.Dust reduced the consistency rate of FY-2F/CTA,increased the strong rate,but it has little effect on the identification of cloud and non-cloud.This study provides an important reference for satellite retrieval and the application of total cloud cover in arid areas.