AIRS晴空大气温度廓线反演试验

Retrieval of clear-air atmospheric temperature profiles using AIRS observations

  • 摘要: 2002年5月发射的Aqua是美国地球观测系统中的第2颗卫星EOS-2(Earth Observing System),它携带的大气红外探测仪AIRS(Atmospheric Infrared Sounder)是目前国际上最先进的超高光谱分辨率红外大气垂直探测仪。1200的光谱分辨率和全球覆盖能力使其可以观测全球大气状态及其变化。对其超高光谱分辨率资料的处理和应用的研究既有科学意义,又有实用价值。利用AIRS实际观测资料反演大气温度,本文使用的是便于处理大数据量的统计反演方法中的特征向量法,计算回归系数使用的是AIRS观测辐射值和T213数值预报分析场。本文从通道个数、地形及地表发射率影响、增加预报因子、国外同类产品比较等4个方面进行了大气温度反演试验研究。研究结果表明:(1)在利用超高光谱分辨率仪器进行反演时,合理选择通道是非常必要的;(2)AIRS反演的大气温度在对流层顶和中上层具有较高的精度,在对流层低层,尤其是近地面反演精度不够理想;(3)增加地表温度,地表发射率和地形3个预报因子,可以提高近地面的反演精度;(4)文中反演的大气温度精度与国外同类产品精度基本一致。

     

    Abstract: Atmospheric Infrared Sounder(AIRS)is on board the EOS-2/ Aqua satellite, launched on May 4, 2002. It is now an advanced atmospheric remote sensing instrument with a super high spectral resolution and a global detection coverage in the world. Study on AIRS data processing is of significance in both science and operational application. In the retrieval of atmospheric temperature from the AIRS observations, the eigenvector method is used, and collocated AIRS brightness temperature and corresponding T213 temperature analyses fields are used to compute the regression coefficients. The study includes the following aspects: selection of spectral channels, impacts of surface emissivity and topography, determination of additional predictors, and comparison of retrieval results. Research results indicate that: (1) it is very essential to rationally choose the channels when retrieving atmospheric temperature with the high spectral resolution AIRS data; (2) AIRS data can significant improve the retrieval accuracy of temperature in mid-upper troposphere and at the tropopause, however in the lower troposphere, especially near the surface, the accuracy is not satisfactory; (3) different surface emissivity and topography will affect retrieval result; (4) factors reflecting surface radiation nature, such as surface temperature, surface emissivity, and topography, are selected as additional predictors, which improves the retrieval accuracy near the surface; (5) AIRS retrieval accuracy in this paper is consistent with the AIRS team's.

     

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