阿克达拉大气本底站地表辐射收支特征

Characteristics of the surface radiation budget of the Akedala atmospheric background station

地表辐射收支变化影响区域乃至全球气候,利用阿克达拉大气本底站基准辐射观测系统的2021年11月1日至2022年10月31日地表辐射四分量数据,分析阿克达拉大气本底站地表辐射与反照率的变化特征。结果表明:(1)太阳总辐射年曝辐量为5772.74 MJ·m^(-2)。太阳总辐射曝辐量的季节变化表现为夏季>春季>秋季>冬季,不同月份太阳总辐射和反射短波辐射日峰值集中在11:00—12:00,地面长波辐射日峰值集中在12:00—13:00,大气逆辐射日峰值出现时间没有明显规律。(2)净收入辐射最大值主要出现在正午,净支出辐射最大值出现时间主要在日落时。(3)降雨对太阳总辐射、反射短波辐射、地面长波辐射、地表反照率具有削弱作用,降雪过程太阳总辐射受到削弱,降雪后地面积雪导致地表反照率增大,地面反射短波辐射增强,日间地面长波辐射和地面净辐射减弱,由于雪对地面的保温作用,夜间地面长波辐射较降雪前增强;降雨与降雪均对大气逆辐射具有增强作用。(4)雨天地表反照率最小值为0.16;当积雪深度达到5 cm时,地表反照率可达0.96,新雪地表反照率大于老雪,且稳定积雪的地表反照率日均值在0.72~0.88。

Changes in surface radiation budgets significantly affect regional and global climates,particularly in arid and semi-arid areas.The underlying surface of the Gobi wetland and desert steppe vegetation in the area surrounding the Akedala atmospheric background station is representative of northern Xinjiang and the hinterland of Asia and Europe.Meanwhile,its atmospheric background is clean and experiences long winter snow,making its surface radiation special.However,research on the radiation budget of the Gobi in northern Xinjiang is limited.Therefore,it is necessary to study the characteristics of its radiation budget.The four components of surface radiation from November 1,2021-October 31,2022 of the Akedala atmospheric background station reference radiation observation system were used to analyze the changes in surface radiation and albedo in different time scales and precipitation processes of Akedala atmospheric background station.The results indicated an annual exposure of total solar radiation of 5772.74 MJ·m^(-2).The seasonal variation of total solar radiation exposure is manifested as the largest in summer,followed by spring,and the smallest in winter.The daily peak of total solar radiation and reflected short-wave radiation in different months is concentrated between 11:00 and 12:00,while the daily peak of ground long-wave radiation is concentrated between 12:00 and 13:00.In addition,the daily peak occurrence time of atmospheric counter radiation is not obvious.The maximum net income radiation occurs mainly at noon,while the net expenditure radiation peaks mainly at sunset.Total solar radiation,reflected short-wave radiation,ground radiation,and surface albedo are weakened during rainfall,while total solar radiation is weakened during snowfall.Ground snow leads to increased surface albedo,while reflected short-wave radiation is enhanced,thereby weakening daytime ground radiation and ground net radiation.Simultaneously,influenced by the thermal insulation effect of snow,ground radiation is enhanced compared to before snowfall at night.Both rainfall and snowfall have an enhanced effect on atmospheric counter radiation.The minimum surface albedo on rainy days is 0.16,while a snow depth of 5 cm can increase surface albedo to 0.96.New snow has a higher surface albedo than old snow,and stable snow has a daily average surface albedo of 0.72-0.88.The changes in the surface radiation budget,surface albedo,and snow albedo in the Gobi wetland are revealed to a certain extent,providing a reference for understanding the evolution of the underlying land surface process of the Gobi wetter in northwest China and offering a theoretical and scientific basis for further exploration of the physical process of land-atmosphere interaction and climate change in arid and semiarid areas of China.