Radiation characteristics of the selected channels for cirrus remote sensing in terahertz waveband and the influence factors for the retrieval method
Received:June 07, 2017  Revised:August 16, 2017  download
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Author NameAffiliationE-mail
LI Shu-Lei National Key Laboratory on Electromagnetic Environmental Effects and Electro-optical Engineering, Army Engineering University lishulei91@gmail.com 
LIU Lei College of Meteorology and Oceanography National University of Defense Technology liuleidll@gmail.com 
GAO Tai-Chang College of Meteorology and Oceanography National University of Defense Technology  
SHI Li-Hua National Key Laboratory on Electromagnetic Environmental Effects and Electro-optical Engineering, Army Engineering University  
QIU Shi National Key Laboratory on Electromagnetic Environmental Effects and Electro-optical Engineering, Army Engineering University  
HU Shuai College of Meteorology and Oceanography National University of Defense Technology  
Abstract:Terahertz is expected to be the best waveband for remote sensing of cirrus. However, the retrieval results of satellite terahertz passive remote sensing are susceptible to different atmospheric conditions. The terahertz radiation was simulated under the clear sky and the cloudy situations, based on the atmospheric radiative transfer simulator. The influences of the surface reflectivity, atmospheric profiles and the middle-low level water clouds to terahertz radiation were analyzed. The retrieval errors caused by these factors were calculated based on the multiple lookup-tables method. The results indicate that the influence caused by changing the surface reflectivity mainly range below 300 GHz, and there is no influence on the selected channels. Among the atmospheric profiles, only changing water vapor profiles and temperature profiles have effects on the retrieval results. When the temperature profile changes are between ±2 K, or the water vapor profile changes are between ±20%, for cirrus whose particle size is above 50 μm and ice water path is above 10 g/m2, the retrieval errors stay below ±20%. For low-level water clouds (cloud base height below 2 km), the effects on retrieval errors can be ignored. The retrieval errors caused by middle-level water clouds increase with the increases of the cloud base height and cloud optical depth.
keywords:cirrus, atmospheric profiles, water clouds, retrieval errors
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Copyright:《Journal of Infrared And Millimeter Waves》