已收录 273157 条政策
 政策提纲
  • 暂无提纲
Global distribution of Earth's surface shortwave radiation budget
[摘要] The monthly mean shortwave (SW) radiation budget at the Earth's surface(SRB) was computed on 2.5-degree longitude-latitude resolution for the17-year period from 1984 to 2000, using a radiative transfer modelaccounting for the key physical parameters that determine the surface SRB,and long-term climatological data from the International Satellite CloudClimatology Project (ISCCP-D2). The model input data were supplemented bydata from the National Centers for Environmental Prediction - NationalCenter for Atmospheric Research (NCEP-NCAR) and European Center for MediumRange Weather Forecasts (ECMWF) Global Reanalysis projects, and other globaldata bases such as TIROS Operational Vertical Sounder (TOVS) and GlobalAerosol Data Set (GADS). The model surface radiative fluxes were validatedagainst surface measurements from 22 stations of the Baseline SurfaceRadiation Network (BSRN) covering the years 1992-2000, and from 700 stationsof the Global Energy Balance Archive (GEBA), covering the period 1984-2000.The model is in good agreement with BSRN and GEBA, with a negative bias of14 and 6.5 Wm-2, respectively. The model is able to reproduceinteresting features of the seasonal and geographical variation of thesurface SW fluxes at global scale. Based on the 17-year average modelresults, the global mean SW downward surface radiation (DSR) is equal to171.6 Wm-2, whereas the net downward (or absorbed) surface SW radiationis equal to 149.4 Wm-2, values that correspond to 50.2 and 43.7% ofthe incoming SW radiation at the top of the Earth's atmosphere. These valuesinvolve a long-term surface albedo equal to 12.9%. Significant increasingtrends in DSR and net DSR fluxes were found, equal to 4.1 and 3.7 Wm-2,respectively, over the 1984-2000 period (equivalent to 2.4 and 2.2 Wm-2per decade), indicating an increasing surface solar radiative heating. Thissurface SW radiative heating is primarily attributed to clouds, especiallylow-level, and secondarily to other parameters such as total precipitablewater. The surface solar heating occurs mainly in the period starting fromthe early 1990s, in contrast to decreasing trend in DSR through the late1980s. The computed global mean DSR and net DSR flux anomalies were found torange within ±8 and ±6 Wm-2, respectively, with signals fromEl Niño and La Niña events, and the Pinatubo eruption, whereassignificant positive anomalies have occurred in the period 1992-2000.
[发布日期]  [发布机构] 
[效力级别]  [学科分类] 大气科学
[关键词]  [时效性] 
   浏览次数:2      统一登录查看全文      激活码登录查看全文