DocumentCode :
2674181
Title :
Combined microwave and hyperspectral infrared retrievals of atmospheric profiles in the presence of clouds using nonlinear stochastic methods
Author :
Blackwell, William J. ; Chen, Frederick W. ; Jairam, Laura G.
Author_Institution :
Massachusetts Inst. of Technol., Lexington
fYear :
2007
fDate :
23-28 July 2007
Firstpage :
2814
Lastpage :
2817
Abstract :
A nonlinear stochastic method for the retrieval of atmospheric temperature and moisture profiles has been developed and evaluated with sounding data from the Atmospheric InfraRed Sounder (AIRS) and the Advanced Microwave Sounding Unit (AMSU), and is presently being adapted for use with the NPOESS Cross-track Infrared Microwave Sounding Suite (CrIMSS) consisting of the hyperspectral Cross-track Infrared Sounder (CrIS) and the Advanced Technology Microwave Sounder (ATMS). The algorithm is implemented in three sequential stages: 1) stochastic cloud clearing (SCC), 2) eigenvector radiance compression and denoising, and 3) neural network (NN) estimation. First, the infrared radiance perturbations due to clouds are estimated and corrected by combined processing of the infrared and microwave data. Second, a Projected Principal Components (PPC) transform is used to reduce the dimensionality of and optimally extract geophysical profile information from the cloud-cleared infrared radiance data. Third, a feedforward neural network is used to estimate the desired geophysical parameters from the projected principal components. The performance of the algorithm (henceforth referred to as SCC/NN) was evaluated using global (ascending and descending) EOS-Aqua orbits co-located with ECMWF forecasts (generated every three hours on a 0.5-degree lat/lon grid) and radiosonde observations (RAOBs) for a variety of days throughout 2003 and 2004. Over 500,000 fields of regard (3times3 arrays of footprints) over ocean and land were used in the study. The performance of the SCC/NN algorithm exceeded that of the AIRS Level 2 (Version 4) algorithm throughout most of the troposphere while achieving approximately four times the yield. Furthermore, the SCC/NN performance in the lowest 1 km of the atmosphere greatly exceeds that of the AIRS Level 2 algorithm as the level of cloudiness increases. The SCC/NN algorithm requires significantly less computation than traditional variational retrieval metho- ds while achieving comparable performance, thus the algorithm is particularly suitable for quick-look retrieval generation for post-launch CrIMSS performance validation.
Keywords :
atmospheric humidity; atmospheric techniques; atmospheric temperature; clouds; geophysical signal processing; neural nets; nonlinear estimation; principal component analysis; remote sensing; stochastic processes; AIRS; AMSU; ATMS; Advanced Microwave Sounding Unit; Advanced Technology Microwave Sounder; Atmospheric Infrared Sounder; CrIMSS; CrIS; NPOESS Crosstrack Infrared Microwave Sounding Suite; PPC transform; SCC-NN algorithm; atmospheric moisture profiles; atmospheric temperature profiles; clouds; dimensionality reduction; eigenvector radiance compression; eigenvector radiance denoising; feedforward neural network; hyperspectral crosstrack infrared sounder; hyperspectral infrared observations; infrared data processing; microwave data processing; microwave observations; neural network estimation; nonlinear stochastic methods; parameter estimation; projected principal component transform; sounding data; stochastic cloud clearing; Clouds; Hyperspectral imaging; Information retrieval; Microwave technology; Microwave theory and techniques; Moisture; Neural networks; Noise reduction; Ocean temperature; Stochastic processes;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007. IEEE International
Conference_Location :
Barcelona
Print_ISBN :
978-1-4244-1211-2
Electronic_ISBN :
978-1-4244-1212-9
Type :
conf
DOI :
10.1109/IGARSS.2007.4423428
Filename :
4423428
Link To Document :
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