Investigating the Comparisons of Hyperspectral IR Sounders, Radio Occultation, and Radiosondes in Radiance Space
Presenter:
Michelle Feltz
University of Wisconsin-Madison, SSEC
University of Wisconsin-Madison, SSEC; ROM SAF, Danish Meteorological Institute
Talk
In recent decades the importance of ensuring continuity and consistency between meteorological satellite datasets has been highlighted. As evidence, GSICS was created in 2005 as an international effort to harmonize the quality of operational weather satellites, projects under NASA’s MEaSUREs have been funded to create merged data records using pre-existing datasets, and networks like GRUAN have been created to coordinate measurements of essential climate variables.
Less focus, however, has been put on the comparisons of satellite datasets which have different measurement techniques—for example between passive and active remote sensing technologies. Though much work has been previously done to compare the active radio occultation (RO), passive hyperspectral infrared (IR) sounder, and radiosonde retrievals for temperature and water vapor profile validation purposes, less work has been done comparing them in radiance or refractivity units—where each the IR sounder and RO have much smaller uncertainties on their measurements.
This work provides a follow-up to previous studies which proved that hyperspectral IR radiances, with their prescribed uncertainties, can be used as a validation reference for RO temperature retrievals via radiative transfer for channels representing the upper troposphere and lower stratosphere. Case study matchups of hyperspectral IR sounders, RO, and radiosondes are used with radiative transfer to compare these datasets in radiance units for the purposes of 1] further characterizing and understanding their differences over the full IR spectral domain, 2] investigating the feasibility of using the IR sounder radiances as truth for channels which represent different regions of the troposphere, given the increased uncertainties of the radiative transfer algorithm for various spectral channels, and 3] prescribing methodological uncertainties to the comparisons.
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