古尔班通古特沙漠地表辐射收支特征

古尔班通古特沙漠是中国最大的固定、半固定沙漠。利用2017年该沙漠克拉美丽站辐射资料，分析了古尔班通古特沙漠不同时间尺度和不同天气条件下的地表辐射变化特征。结果表明：（1）不同月份沙漠辐射收支各分量月平均日变化均呈单峰型，但极值大小及出现时间存在差异。各分量曝辐量季节变化明显：太阳总辐射表现为生长期（4—9月）>积雪期（1—3月）>凋零期（10—12月），反射短波辐射表现为积雪期>生长期>凋零期，长波辐射和净辐射均表现为生长期>凋零期>积雪期。（2）地表反照率4—11月的日变化均呈“U”型曲线，年均值为0.367，积雪期、生长期、凋零期的平均值分别为0.7、0.246和0.27，其中1月1日至3月15日的日均值均高于0.7，这是该期间古尔班通古特沙漠存在稳定积雪所致。（3）晴天各分量日变化均为倒“U”型曲线，多云和雨天则不如晴天平滑，雪天短波辐射和净辐射日变化呈倒“V”型，长波辐射无明显日变化。降雨前后地表反照率日均值表现为雨前晴天>雨后晴天>雨天，降雪前后表现为雪后晴天>雪天>雪前晴天。（4）融雪前后各分量变化明显，积雪快速融化时地表反照率和反射短波辐射逐日减小，净辐射则反之，积雪完全融化前地表长波辐射一直较弱，积雪完全融化后逐渐增强。

Characteristics of surface radiation budget in Gurbantunggut Desert

As the largest fixed and semifixed desert in China,the Gurbantunggut Desert presents the obvious variety on local surface radiation budget and energy balance.In order to clarify the law of evolution of the surface radiation budget over the desert,the variation characteristics of the desert surface radiation under different time scales and different weather conditions were analyzed by using the radiation data of the Kelameili observation station in the hinterland of Gurbantunggut Desert in 2017.The results showed that:(1)The monthly mean diurnal variation curves of surface radiation components were all in unimodal type,but extreme values of which appeared at different times and were unequal.The monthly total variation of surface radiation components were obvious:mean monthly total of the downward long-wave radiation were ranked as growth phase(April-September)>snow cover phase(January-March)>withering phase(October-December),and which of upward shortwave radiation ranked as snow cover phase>growth phase>withering phase,while which of long-wave radiation and net radiation were all ranked as growth phase>withering phase>snow cover phase.(2)The monthly mean diurnal variation of surface albedo were all in U-shaped curves from April to November.The annual mean value was 0.367.The average values of snow cover phase,growth phase,and withering phase were 0.7,0.246,and 0.27,respectively.The daily mean values was greater than 0.7 from January 1 to March 15 because Gurbantunggut Desert has been covered within the snow covered continuously during this period.(3)On clear day,The diurnal variation of surface radiation components was smooth inverted U-shaped curves,while which on cloudy and rainy day became irregular.On snow day,the diurnal variation of short-wave radiation and net radiation were inverted V-shaped curve,while which of long-wave radiation was inconspicuous.During the rainfall and snowfall periods,the daily mean values of surface albedo were ranked as the day before rainfall>the day after rainfall>rainy day and as the day after snowfall>snow day>the day before snowfall,respectively.(4)During the snowmelt period,the variation of radiation components was obvious:the daily mean value of surface albedo and upward short-wave radiation decreased day by day when snow cover melted rapidly,while which of net radiation increased.Before snow cover had melted completely,the diurnal variation of long-wave radiation was inconspicuous,but which after snow cover melted completely increased.