Radiance comparison of IASI and AVHRR on MetOp-A

Likun Wang; Changyong Cao

doi:10.1117/12.730391

24 September 2007 Radiance comparison of IASI and AVHRR on MetOp-A

Likun Wang, Changyong Cao

Proceedings Volume 6684, Atmospheric and Environmental Remote Sensing Data Processing and Utilization III: Readiness for GEOSS; 668417 (2007) https://doi.org/10.1117/12.730391
Event: Optical Engineering + Applications, 2007, San Diego, California, United States

Abstract

Accurate and precise satellite radiance measurements are important for data assimilations in numerical weather prediction models and climate change detection. Given the high-resolution spectral IASI measurements with high data quality, it allows us to assess the radiance measurements of 'heritage' instruments that share the same spectral region with IASI. In this study, we demonstrate the utility of the IASI radiances to evaluate the AVHRR IR channel observations. The IASI spectral radiances are convolved with the AVHRR SRFs (Spectral Response Functions) to produce the IASI-convolved AVHRR radiances. The co-registered AVHRR pixels inside each IASI pixel are averaged to compare with IASI. We analyzed one-orbit data on 21 June 2007, and preliminary comparison has been performed. Statistically, the temperature observed from AVHRR channels 4 and 5 is slightly warmer than IASI. The mean BT difference (IASI minus AVHRR) is -0.35K for channels 4 and -0.16 K for channel 5 with a standard deviation of 0.5K. The BT difference between IASI and AVHRR IR channels is scene-temperature dependent for both channels 4 and 5, possibly caused by the nonlinearity of detector. Both AVHRR Channel 4 and channel 5 show slightly symmetric dependence on scan angle with maximum differences of approximately ~0.2 K (AVHRR warmer than IASI) at both ends of the scan (with respect to the difference at nadir). However, the root cause of the bias still needs to be investigated by analyzing more datasets.

Citation Download Citation

Likun Wang and Changyong Cao "Radiance comparison of IASI and AVHRR on MetOp-A", Proc. SPIE 6684, Atmospheric and Environmental Remote Sensing Data Processing and Utilization III: Readiness for GEOSS, 668417 (24 September 2007); https://doi.org/10.1117/12.730391

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