AMTD Atmospheric Measurement Techniques Discussions AMTD Atmos. Meas. Tech. Discuss. 1867-8610 Göttingen, Germany 10.5194/amtd-3-2833-2010 Characterization of merged AIRS and MLS water vapor sensitivity through integration of averaging kernels and retrievals Liang C. K. 1 2 Eldering A. 2 Irion F. W. 2 Read W. G. 2 Fetzer E. J. 2 Kahn B. H. 2 Liou K.-N. 1 Joint Institute for Regional Earth System Science and Engineering, Los Angeles, California, USA Jet Propulsion Laboratory/California Institute of Technology, Pasadena, California, USA 06 07 2010 3 4 2833 2859 Copyright: © 2010 C. K. Liang et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://amt.copernicus.org/preprints/3/2833/2010/amtd-3-2833-2010.html The full text article is available as a PDF file from https://amt.copernicus.org/preprints/3/2833/2010/amtd-3-2833-2010.pdf

In this paper, we analyze averaging kernels to assess the sensitivity of the Aqua Atmospheric Infrared Sounder (AIRS) and Aura Microwave Limb Sounder (MLS) to water vapor. The averaging kernels, in the tropical and extra-tropical upper tropospheric and lower stratospheric region of the atmosphere, indicate that AIRS is primarily sensitive to water vapor concentrations typical of tropospheric values up to a level around 260 hPa. At lower pressures AIRS retrievals lose sensitivity to water vapor, though not completely as indicated by the non-zero verticalities at pressures less than 260 hPa. The MLS is able to provide high quality retrievals, with verticalities ~1 for all pressure levels, down to the same level for where AIRS begins to lose sensitivity. Previous analyses have estimated both instruments to have overlapping sensitivity to water vapor over a half temperature scale height layer, within the upper troposphere, for concentrations between ~30–400 ppmv. Thus, we implement a method using the averaging kernel information to join the AIRS and MLS profiles into an merged set of water vapor profiles. The final combined profiles are not only smooth functions with height but preserve the atmospheric state as interpreted by both the AIRS and MLS instruments.

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