Evaluating the Diurnal Cycle of Upper Tropospheric Humidity in Two Different Climate Models Using Satellite Observations

Remote Sensing

Kesavapillai Mohanakumar¹  Ajil Kottayil¹  Viju O. John²  Stefan A. Buehler³ 

[1] Advanced Centre for Atmospheric Radar Research, Cochin University of Science and Technology, Kerala 682022, India;EUMETSAT, Darmstadt 64295, Germany;Meteorological Institute, University of Hamburg, Hamburg 20146, Germany;

关键词: upper tropospheric humidity;    diurnal cycle;    microwave;    infrared;    convection;    climate models;   

DOI  :  10.3390/rs8040325

来源: DOAJ

【 摘 要 】

The diurnal cycle of upper tropospheric humidity (UTH) is known to be influenced by such processes as convection and the formation of clouds which are parameterized in current global climate models. In this study, we evaluate the performance of two climate models, the Community Atmospheric Model version 5 (CAM-5) and the Global Atmosphere 3.0 (GA-3) model in simulating the diurnal cycle of UTH (represented by a combination of sinusoids of 12 and 24 h periods) by comparing with microwave and infrared (IR) measurements (where available). These comparisons were made over two convective land regions in South America and Africa, and over oceanic regions in the Atlantic, Indian and West Pacific for the month of January 2007. We analyzed how the diurnal cycles from IR and microwave instruments differ, and the reason for the differences. Our study suggests that the differences in the diurnal cycles of IR and microwave UTH result from sampling differences due to the presence of clouds. As noted by earlier studies, the models exhibit considerable discrepancies in diurnal amplitude and phase relative to observations, and these discrepancies have different magnitudes over land and ocean.

【 授权许可】

Unknown