摘要
中分辨率成像光谱仪(MODIS)已成为研究云的微物理特征的重要数据来源,它提供的云水路径(LWP)产品已被广泛运用到各类研究中.但MODIS采用的光谱反演方法会在冰云存在的情况下导致大量下方水云LWP的漏测,而基于被动微波信号的反演算法则可反演出这类云的LWP.本文利用准同步的被动微波仪器AMSR-E的反演结果定量评估了2002~2011年间MODIS对于洋面LWP的漏测情况,结果发现:在全球洋面上空,MODIS漏测水云的比例约为10.8%,平均漏测的LWP约为0.15 kg/m^2.漏测样本主要分布在赤道和西太平洋暖池等利于混合云发展的海域上空.一般而言,所漏测的水云容易发生在云顶温度(CTT)低、冰水含量高的深厚对流云中,且这类漏测样本通常具有较高的LWP.当CTT处于205~235 K区间时,MODIS漏测水云的样本最多.此外,利用辐射传输模式模拟了因漏测而造成的全球辐射平衡计算差异,结果表明,由于MODIS漏测的水云将导致对地气系统辐射强迫的低估,进而造成对地气系统温度的低估.
Liquid water path(LWP)from Moderate Resolution Imaging Spectroradiometer(MODIS)measurement has been used as an important data source in cloud microphysics studies.However,due to the limitation of the visible-band retrieval methods under ice cloud conditions,the LWPs of mixed clouds are usually missed by MODIS.Another retrieval algorithm based on microwave signals can avoid the limitation.In this study,ten years(2002~2011)of microwave-derived and MODIS-retrieved LWP over oceans were compared.The result shows that the failures of MODIS detection are found to be most frequent over the equator and the Tropical Warm Pool region.In addition,the global missed rate of MODIS LWP is^10.8%and the averaged underestimation is^0.15 kg/m^2.The missed rates and mean missed LWP values have a strong correlation with ice water path(IWP)and cloud top temperature(CTT).Generally,well-developed convective clouds with colder tops and more ice water content are associated with higher missing frequency and mean LWP.Among all missed LWPs,clouds with CTT within 205~235K are most frequent.In addition,simulations were conducted on how MODIS missed LWP effects on the global radiation budget.The result shows that there is an underestimation of globally radiative forcing due to the MODIS missed LWP,which results in an underestimation of temperature of the earth-atmosphere system.
作者
李江妹
王雨
LI Jiangmei;WANG Yu(School of Earth and Sciences, University of Science and Technology of China, Hefei 230026, China)
出处
《中国科学技术大学学报》
CAS
CSCD
北大核心
2019年第11期912-919,929,共9页
JUSTC
基金
国家自然科学基金(41375030,41875024)
国家重点研发计划(2018YFC1507401,2017YFC1501402)
中央高校基本科研业务费专项资金资助.
