Retrieval of methane profiles from spaceborne hyperspectralinfrared observations
利用卫星红外高光谱资料反演大气甲烷浓度垂直廓线

This paper presents an improved Empirical Orthogonal Functions (EOF) model for estimating methane profilesfrom spaceborne hyperspectral infrared observations based on profile dataset from European Centre for Medium-RangeWeather Forecasts (ECMWF) and radiative transfer model RTTOV9.3. The model was applied to Atmospheric InfraredSounder (AIRS) observations, validated by ground-based Fourier Transform Spectrometer (FTS) observations and AIRS v5.0 CH4 products. Compared with FTS measurements, the Root Mean Square (RMS) relative error of CH4 mixing ratio of EOFretrieval was smaller than that of AIRS v5.0 CH4 product for data lower than 300 hPa, and the relative error of CH4 columnamount of EOF retrieval was also smaller. Compared with AIRS v5.0 CH4 product, the coefficient of determination for CH4profiles retrieved from EOF model was 0.9715, and the RMS relative errors were smaller than 2.5%. The validation resultsshow that the EOF model could provide a good initial value for physical retrieval and is a promising operational approach dueto high stability and efficiency.