Characterization and evaluation of AIRS-based estimates of the deuterium content of water vapor

Worden, John R.; Kulawik, Susan S.; Fu, Dejian; Payne, Vivienne H.; Lipton, Alan E.; Polonsky, Igor; He, Yuguang; Cady-Pereira, Karen; Moncet, Jean-Luc; Herman, Robert L.; Irion, Fredrick W.; Bowman, Kevin W.

Single-pixel tropospheric retrievals of HDO and inline-formulaH2O concentrations are retrieved from Atmospheric Infrared Sounder (AIRS) radiances using the optimal estimation algorithm developed for the Aura Tropospheric Emission Spectrometer (TES) project. We evaluate the error characteristics and vertical sensitivity of AIRS measurements corresponding to 5 d of TES data (or five global surveys) during the Northern Hemisphere summers between 2006 and 2010 (inline-formula∼600 co-located comparisons per day). We find that the retrieval characteristics of the AIRS deuterium content measurements have similar vertical resolution in the middle troposphere as TES but with slightly less sensitivity in the lowermost troposphere, with a typical degrees of freedom (DOFS) in the tropics of 1.5. The calculated measurement uncertainty is inline-formula∼30 ‰ (parts per thousand relative to the deuterium composition of ocean water) for a tropospheric average between 750 and 350 hPa, the altitude region where AIRS is most sensitive, compared to inline-formula∼15 ‰ for the TES data. Comparison with the TES data also indicates that the uncertainty of a single target AIRS HDO inline-formula∕inline-formulaH2O measurement is inline-formula∼30 ‰. Comparison of AIRS and TES data between 30inline-formula S and 50inline-formula N indicates that the AIRS data are biased low by inline-formula M10inlinescrollmathml - normal 2.6 35pt10ptsvg-formulamathimga2a3c8be915c8002c3e0b6d5947b3b15 amt-12-2331-2019-ie00001.svg35pt10ptamt-12-2331-2019-ie00001.png  ‰ with a latitudinal variation of inline-formula∼7.8 ‰. This latitudinal variation is consistent with the accuracy of TES data compared to in situ measurements, suggesting that both AIRS and TES have similar accuracy.



Worden, John R. / Kulawik, Susan S. / Fu, Dejian / et al: Characterization and evaluation of AIRS-based estimates of the deuterium content of water vapor. 2019. Copernicus Publications.


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