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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union

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Atmos. Meas. Tech., 10, 745-758, 2017
https://doi.org/10.5194/amt-10-745-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
07 Mar 2017
Field-of-view characteristics and resolution matching for the Global Precipitation Measurement (GPM) Microwave Imager (GMI)
Grant W. Petty1 and Ralf Bennartz2 1Atmospheric and Oceanic Sciences, University of Wisconsin, 1225 W. Dayton St., Madison, WI, 53706, USA
2Earth and Environmental Sciences, Vanderbilt University, 5726 Stevenson Center, Nashville, TN 37240, USA
Abstract. Representative parameters of the scan geometry are empirically determined for the Global Precipitation Measurement (GPM) Microwave Imager (GMI). Effective fields of view (EFOVs) are computed for the GMI's 13 channels, taking into account the blurring effect of the measurement interval on the instantaneous fields of view (IFOVs). Using a Backus–Gilbert procedure, coefficients are derived that yield an approximate spatial match between synthetic EFOVs of different channels, using the 18.7 GHz channels as a target and with due consideration of the tradeoff between the quality of the fit and noise amplification and edge effects. Modest improvement in resolution is achieved for the 10.65 GHz channels, albeit with slight ringing in the vicinity of coastlines and other sharp brightness temperature gradients. For all other channels, resolution is coarsened to approximate the 18.7 GHz EFOV. It is shown that the resolution matching procedure reduces nonlinear correlations between channels in the presence of coastlines as well as enables the more efficient separation of large brightness temperature variations due to coastlines from the much smaller variations due to other geophysical variables. As a byproduct of this work, we report accurate EFOV resolutions as well as a self-consistent set of parameters for modeling the scan geometry of the GMI.
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Citation: Petty, G. W. and Bennartz, R.: Field-of-view characteristics and resolution matching for the Global Precipitation Measurement (GPM) Microwave Imager (GMI), Atmos. Meas. Tech., 10, 745-758, https://doi.org/10.5194/amt-10-745-2017, 2017.
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Short summary
The Global Precipitation Measurement (GPM) Microwave Imager (GMI) is a new satellite instrument for observing global rainfall and snowfall. This paper documents the effective spatial resolution of the GMI's microwave imagery and describes the results of a computational method for optimally matching the resolutions of different channels.
The Global Precipitation Measurement (GPM) Microwave Imager (GMI) is a new satellite instrument...
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