The Significant Role of Radiosonde-measured Cloud-base Height in the Estimation of Cloud Radiative Forcing  

作　　者：Hui XU Jianping GUO Jian LI Lin LIU Tianmeng CHEN Xiaoran GUO Yanmin LYU Ding WANG Yi HAN Qi CHEN Yong ZHANG 

机构地区：[1]State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081,China [2]College of Earth Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [3]Meteorological Observation Center,China Meteorological Administration,Beijing 100081,China

出　　处：《Advances in Atmospheric Sciences》2021年第9期1552-1565,共14页大气科学进展（英文版）

基　　金：support from the National Key R&D Program of China under Grants Nos.2017YFC1501401 and 2017YFC0212803;the National Natural Science Foundation under Grant No.41771399;the Chinese Academy of Meteorological Sciences under Grant No.2018Y014。

摘　　要：The satellite-based quantification of cloud radiative forcing remains poorly understood,due largely to the limitation or uncertainties in characterizing cloud-base height(CBH).Here,we use the CBH data from radiosonde measurements over China in combination with the collocated cloud-top height(CTH) and cloud properties from MODIS/Aqua to quantify the impact of CBH on shortwave cloud radiative forcing(SWCRF).The climatological mean SWCRF at the surface(SWCRFSUR),at the top of the atmosphere(SWCRFTOA),and in the atmosphere(SWCRFATM) are estimated to be-97.14,-84.35,and 12.79 W m^(-2),respectively for the summers spanning 2010 to 2018 over China.To illustrate the role of the cloud base,we assume four scenarios according to vertical profile patterns of cloud optical depth(COD).Using the CTH and cloud properties from MODIS alone results in large uncertainties for the estimation of SWCRFATM,compared with those under scenarios that consider the CBH.Furthermore,the biases of the CERES estimation of SWCRFATM tend to increase in the presence of thick clouds with low CBH.Additionally,the discrepancy of SWCRFATM relative to that calculated without consideration of CBH varies according to the vertical profile of COD.When a uniform COD vertical profile is assumed,the largest SWCRF discrepancies occur during the early morning or late afternoon.By comparison,the two-point COD vertical distribution assumption has the largest uncertainties occurring at noon when the solar irradiation peaks.These findings justify the urgent need to consider the cloud vertical structures when calculating the SWCRF which is otherwise neglected.

关 键 词：cloud base height RADIOSONDE radiative forcing China CLIMATOLOGY 

分 类 号：P412.23[天文地球—大气科学及气象学]