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.
The temporal and spatial variations and causes of aerosol optical depth(AOD)in Shaanxi Province were investigated based on the Moderate Resolution Imaging Spectroradiometer(MODIS)derived aerosol data for the period of March 2000–February 2012.The results showed that the distribution of aerosol was largely affected by topography and local economic activities.Heavy aerosol loading and increasing tendency in AOD was observed in Guanzhong,Hanzhong and Ankang basin,while a reverse tendency was revealed in most other regions.The spatial distribution of aerosol Angstrom wavelength exponent was predominantly related to vegetation coverage in Shaanxi.Airborne dust from ground is an important source of coarse mode aerosols.Vegetation improvement indicated by an increase in normalized difference vegetation index(NDVI)and a reduction in dust weather led to a gradual decrease in coarse mode AOD to the north of Qinling Mountains in Shaanxi,while anthropogenic activities led to an increase in fine mode AOD in other areas except those covered by forests.The main aerosol type gradually shifted to the urban industrial type in Shaanxi.
