GOES-16 ABI观测和ERA5全天空模拟亮温揭示的热带对流水平特征尺度对比分析  

Comparison of tropical convection horizontal scales between GOES-16 ABI TB observations and ERA5 all sky simulations

作　　者：汪栩涛 邹晓蕾[1] WANG Xutao;ZOU Xiaolei(Joint Center of Data Assimilation for Research and Application,Nanjing University of Information Science&Technology,Nanjing 210044,China)

机构地区：[1]南京信息工程大学资料同化研究和应用联合中心,南京210044

出　　处：《气象科学》2024年第1期125-137,共13页Journal of the Meteorological Sciences

基　　金：国家重点研发计划资助项目(2018YFC1507004)。

摘　　要：本研究通过将GOES-16 ABI观测亮温和ERA5再分析资料的全天空模拟亮温进行对比分析,发现观测亮温和模拟亮温对流低值区位置大体接近,也能够定性反映出对流从发展到减弱的日变化过程,但亮温低值区域的强度存在较大差异。即使把高分辨率ABI通道13观测亮温平均到ERA5分辨率(0.25°×0.25°),在热带对流区的低亮温强度仍然高于ERA5全天空模拟亮温。因此利用主成分分析(Principal Component Analysis,PCA)和离散傅里叶变换(Discrete Fourier Transform,DFT)对任意选择的两对流区域内的观测和模拟亮温进行了尺度分析和对比。在其中对流较强的区域内,当ABI观测亮温的主成分分量从1增加到9时,水平特征尺度从700 km逐渐减小到150 km。ERA5全天空模拟亮温从主成分1增加到4时,水平特征尺度从950 km减小到270 km空间尺度,但当主成分4增加到9时,特征尺度几乎不变。在对流较弱的另一区域也能够发现ERA5模拟亮温对对流水平特征尺度有明显高估。ERA5模拟亮温各主成分的相位和观测亮温存在2 h以内的误差。由于ERA5全天空模拟亮温低值区与ERA5云冰路径大值区吻合度较高,由此可以推测ERA5云冰路径误差是造成ERA5全天空模拟亮温与ABI观测亮温差别的主要原因之一。In this study,GOES-16 Advanced Baseline Imager Temperature Brightness(ABI TB)observations were compared with all-sky simulations of ERA5 reanalysis data.It is found that the ERA5 simulated low TB areas are nearly consistent with those of observations,and qualitatively reflect a diurnal variation from a developing to weakening process of convection.However,there are significant differences in how low TB reached.Even if the high-resolution(2 km)channel-13 TB observations are averaged to the ERA5 resolution(0.25°×0.25°),they are still lower than the ERA5 all-sky simulations.By using Principal Component Analysis(PCA)and Discrete Fourier Transform(DFT)methods,a scale analysis on the observed and simulated TB fields in two arbitrarily selected convective areas was conducted.In the area where convection is strong,the horizontal scales gradually decrease from 700 km to 150 km for principal components of TB observations from 1 to 9.However,the horizontal scales gradually decrease from 950 km to 270 km for the principal components of ERA5 all-sky simulations from 1 to 4,but hardly change from 4 to 9.In another area with weaker convection,it can also be observed that the ERA5 simulated TB significantly overestimates the horizontal characteristic scale of convection.For ERA5 simulated TB,there is an error of within two hours for the phase of each main component compared with ABI TB observations.Since the low-TB areas of the ERA5 all-sky simulations coincide highly with the areas of large ice water path,it can be speculated that the ice water path in the ERA5 reanalysis is responsible for the differences of spatial distributions and intensity changes of TBs between ERA5 all-sky simulations and ABI observations.

关 键 词：热带对流 静止卫星观测 全天空模拟 尺度分析 

分 类 号：P407[天文地球—大气科学及气象学]