Effects of Clouds and Aerosols on Surface Radiation Budget Inferred from DOE AMF at Shouxian, China

Based on data collected during the first U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) field campaigns at Shouxian, eastern China in 2008, the effects of clouds and aerosols on the surface radiation budget during the period October–December 2008 were studied. The results revealed that the largest longwave (LW), shortwave (SW), and net Aerosol Radiative Effects (AREs) are 12.7, –37.6, and –24.9 W m–2, indicating that aerosols have LW warming impact, a strong SW cooling effect, and a net cooling effect on the surface radiation budget at Shouxian during the study period 15 October–15 December 2008. The SW cloud radiative forcing (CRF) is –135.1 W m–2, much cooler than ARE (about 3.6 times), however, the LW CRF is 43.6 W m–2, much warmer than ARE, and resulting in a net CRF of –91.5 W m–2, about 3.7 times of net ARE. These results suggest that the clouds have much stronger LW warming effect and SW cooling effect on the surface radiation budget than AREs. The net surface radiation budget is dominated by SW cooling effect for both ARE and CRF. Furthermore, the precipitatable clouds (PCs) have the largest SW cooling effect and LW warming effect, while optically thin high clouds have the smallest cooling effect and LW warming on the surface radiation budget. Comparing the two selected caseds, CloudSat cloud radar reflectivity agrees very well with the AMF (ARM Mobile Facility) WACR (W-band ARM Cloud Radar) measurements, particularly for cirrus cloud case. These result will provide a ground truth to validate the model simulations in the future.