TY - JOUR
T1 - Using AIRS and ARM SGP Clear-Sky Observations to Evaluate Meteorological Reanalyses
T2 - A Hyperspectral Radiance Closure Approach
AU - Chen, Xiuhong
AU - Huang, Xianglei
AU - Dong, Xiquan
AU - Xi, Baike
AU - Dolinar, Erica K.
AU - Loeb, Norman G.
AU - Kato, Seiji
AU - Stackhouse, Paul W.
AU - Bosilovich, Michael G.
N1 - Funding Information:
We wish to thank three anonymous reviewers for their thoughtful comments. The PCRTM used in this study is provided by X. Liu at NASA Langley. The AIRS Level-1b data are obtained from http://airsl1.gesdisc.eosdis.nasa.gov/data/ Aqua_AIRS_Level1/AIRIBRAD.005/, and AIRS Level 2 data are obtained from http://airsl2.gesdisc.eosdis.nasa.gov/data/Aqua_AIRS_Level2/AIRS2RET.006/. MERRA-2 data are downloaded from https://disc.sci.gsfc.nasa.gov/daac-bin/FTPSubset2.pl. The ECMWF ERA-Interim data are from http://apps.ecmwf.int/datasets/data/interim-full-daily/. The ground-based data can be obtained from the Atmospheric Radiation Measurement (ARM) Program sponsored by the U.S. Department of Energy (DOE) Office of Energy Research, Office of Health and Environmental Research, Environmental Sciences Division and can be downloaded from http://www.archive.arm.gov/. This research is supported by NASA grant NNX16AB37G awarded to the University of Michigan. Researchers from University of Arizona are supported by the NASA CERES project under grant NNX17AC52G.
Funding Information:
We wish to thank three anonymous reviewers for their thoughtful comments. The PCRTM used in this study is provided by X. Liu at NASA Langley. The AIRS Level-1b data are obtained from http://airsl1.gesdisc. eosdis.nasa.gov/data/ Aqua_AIRS_ Level1/AIRIBRAD.005/, and AIRS Level 2 data are obtained from http://airsl2. gesdisc.eosdis.nasa.gov/data/Aqua_ AIRS_Level2/AIRS2RET.006/. MERRA-2 data are downloaded from https://disc. sci.gsfc.nasa.gov/daac-bin/FTPSubset2. pl. The ECMWF ERA-Interim data are from http://apps.ecmwf.int/datasets/ data/interim-full-daily/. The ground- based data can be obtained from the Atmospheric Radiation Measurement (ARM) Program sponsored by the U.S. Department of Energy (DOE) Office of Energy Research, Office of Health and Environmental Research, Environmental Sciences Division and can be downloaded from http://www.archive. arm.gov/. This research is supported by NASA grant NNX16AB37G awarded to the University of Michigan. Researchers from University of Arizona are supported by the NASA CERES project under grant NNX17AC52G.
Publisher Copyright:
©2018. American Geophysical Union. All Rights Reserved.
PY - 2018/10/27
Y1 - 2018/10/27
N2 - Using the ground-based measurements from the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site and spectral radiance from the Atmospheric Infrared Sounder (AIRS) on National Aeronautics and Space Administration Aqua, we evaluate the temperature and humidity profiles from European Center for Medium Range Weather Forecasting ERA-Interim and Modern-Era Retrospective analysis for Research and Applications Version 2 reanalyses. Four sets of synthetic AIRS spectra are calculated using 51 clear-sky sounding profiles from the ARM SGP observations, the collocated AIRS L2 retrievals and the two reanalyses, respectively. A subset of AIRS channels sensitive to temperature, CO2, or H2O but not to other trace gases is chosen and further categorized into different groups according to the peak altitudes of their weighting functions. Synthetic radiances are then compared to the observed AIRS radiances for each group. For all groups, the observed AIRS radiances agree well with the synthetic ones based on the ARM SGP soundings or the AIRS L2 retrievals. The brightness temperature (BT) differences are within ±0.5 K. For two reanalyses, BT differences in all temperature-sensitive groups are generally within ±0.5 K; but the mean BT differences in all groups sensitive to both T and H2O are negative. Together, they suggest a wet bias in the free troposphere in both reanalyses. Moreover, such BT differences can be seen in the analysis of AIRS clear-sky radiances over the entire 30–40°N zone. A grid-search retrieval suggests that 9–30% reduction for reanalysis humidity between 200 and 800 hPa is needed to correct such wet bias.
AB - Using the ground-based measurements from the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site and spectral radiance from the Atmospheric Infrared Sounder (AIRS) on National Aeronautics and Space Administration Aqua, we evaluate the temperature and humidity profiles from European Center for Medium Range Weather Forecasting ERA-Interim and Modern-Era Retrospective analysis for Research and Applications Version 2 reanalyses. Four sets of synthetic AIRS spectra are calculated using 51 clear-sky sounding profiles from the ARM SGP observations, the collocated AIRS L2 retrievals and the two reanalyses, respectively. A subset of AIRS channels sensitive to temperature, CO2, or H2O but not to other trace gases is chosen and further categorized into different groups according to the peak altitudes of their weighting functions. Synthetic radiances are then compared to the observed AIRS radiances for each group. For all groups, the observed AIRS radiances agree well with the synthetic ones based on the ARM SGP soundings or the AIRS L2 retrievals. The brightness temperature (BT) differences are within ±0.5 K. For two reanalyses, BT differences in all temperature-sensitive groups are generally within ±0.5 K; but the mean BT differences in all groups sensitive to both T and H2O are negative. Together, they suggest a wet bias in the free troposphere in both reanalyses. Moreover, such BT differences can be seen in the analysis of AIRS clear-sky radiances over the entire 30–40°N zone. A grid-search retrieval suggests that 9–30% reduction for reanalysis humidity between 200 and 800 hPa is needed to correct such wet bias.
KW - AIRS radiances
KW - ARM soundings
KW - reanalysis bias correction
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U2 - 10.1029/2018JD028850
DO - 10.1029/2018JD028850
M3 - Article
AN - SCOPUS:85055124614
SN - 2169-897X
VL - 123
SP - 11,720-11,734
JO - Journal of Geophysical Research Atmospheres
JF - Journal of Geophysical Research Atmospheres
IS - 20
ER -