利用MODIS和CERES遥感数据研究青藏高原的云辐射强迫效应  

The Analysis of the Cloud’s Radiative Forcing Effect over Qinghai-Xizang Plateau Based on MODIS and CERES Data

作　　者：陈光灿 李函璐 傅云飞[1] CHEN Guangcan;LI Hanlu;FU Yunfei(School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,Anhui,China)

机构地区：[1]中国科学技术大学地球和空间科学学院,安徽合肥230026

出　　处：《高原气象》2021年第1期15-27,共13页Plateau Meteorology

基　　金：国家自然科学基金项目(91837310,41675041);第二次青藏高原综合科学考察研究项目(2019QZKK0104);国家重点研发计划课题(2018YFC1507200,2017YFC1501402);国家公益性行业支撑项目(GYHY201406001);安徽省重点研究与开发计划(201904a07020099)。

摘　　要：准确估算青藏高原的云辐射效应,对分析该地区的近地面感热通量十分重要。本文首先利用加权平均方法,分别将中分辨率成像光谱仪(MODIS)、测云雷达(CPR)和云与地球辐射能量系统(CERES)的像元数据进行融合。利用这些数据,分析了青藏高原上多云个例(2017年5月5日)与少云个例(2017年8月2日)情况下的可见光通道和热红外通道的信号、云参数和大气长短波辐射强迫等的差异。研究表明,少云时高原地区的大气顶大气长波辐射强迫为108.3 W·m-2,多云时为104.5 W·m-2。同时少云个例中塔里木盆地的大气顶大气长波辐射强迫为200.7 W·m-2,表明该辐射强迫受到地表热力状况影响较大。深厚与浅薄云区的云顶高度相差不大,但多云个例中深厚云区的短波辐射强迫是浅薄云区的2倍多,这一比例远大于长波。这表明短波辐射强迫对云厚度较敏感。最后,本文分析了CERES观测的大气顶长短波辐射分别与MODIS热红外和可见光通道之间的关系,结果表明它们存在很好的相关性(相关系数超过0.95),MODIS的可见光通道可以用于估算大气顶的短波辐射量,而MODIS的热红外通道只可用来估算云区的大气顶长波辐射量。Accurate estimation of cloud radiation effects on the Qinghai-Xizang Plateau is essential for analyzing the near-surface sensible heat flux. The weighted average method was used to merge the data of MODerate-resolution Imaging Spectroradiometer(MODIS),CloudSat Profiling Radar(CPR),and Clouds and the Earth’s Radiant Energy System(CERES). The discrepancy between the visible and infrared channel,cloud parameter,and the radiative forcing(RF)in two cases(May 5,2017 for cloudy,August 2,2017 for cloudless)were analyzed base on the merged data. The results show that the atmospheric longwave RF at the top of the atmosphere(TOA)in the cloudless case is 108. 3 W·m-2,in the cloudy case is 104. 5 W·m-2. The atmospheric longwave RF at the TOA on the Tarim Basin is 200. 7 W·m-2 in the cloudless case. It indicates that longwave RF is strongly influenced by surface thermal conditions. The results also show that there exists a little discrepancy between the deep and the shallow cloud at the cloud top height. The shortwave RF of the deep cloud in the cloudy case is more than twice that of the shallow cloud. This ratio is much larger than that of the longwave. It indicates that shortwave RF is more sensitive to cloud thickness. Finally,not only the relationship between the longwave radiation and infrared signal but also the relationship between the shortwave radiation and visible signal were simultaneously analyzed. The results show that they both have a strong correlation(correlation coefficients exceed 0. 95),indicating the signals of the visible channels measured by MODIS can be used to estimate the shortwave radiation at the TOA,while the signals of the thermal channels can only be used to estimate the longwave radiation at the TOA at the cloudy condition.

关 键 词：青藏高原 云 中分辨率成像光谱仪 云与地球辐射能量系统 辐射强迫 

分 类 号：P422.2[天文地球—大气科学及气象学]