Article Type:
Research Article

On the Consequences of Resampling Microwave Radiometer Observations for Use in Retrieval Algorithms

Anita D. Rapp Cooperative Institute for Research in Environmental Sciences, University of Colorado, and NOAA/Earth System Research Laboratory, Boulder, Colorado

Search for other papers by Anita D. Rapp in
Current site
Google Scholar
PubMed Close
,
M. Lebsock Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado

Search for other papers by M. Lebsock in
Current site
Google Scholar
PubMed Close
, and
C. Kummerow Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado

Search for other papers by C. Kummerow in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Sep 2009
DOI:
https://doi.org/10.1175/2009JAMC2155.1
Page(s):
1981–1993
Restricted access

Abstract

How to deal with the different spatial resolutions of multifrequency satellite microwave radiometer measurements is a common problem in retrievals of cloud properties and rainfall. Data convolution and deconvolution is a common approach to resampling the measurements to a single resolution. Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) measurements are resampled to the resolution of the 19-GHz field of view for use in a multifrequency optimal estimation retrieval algorithm of cloud liquid water path, total precipitable water, and wind speed. Resampling the TMI measurements is found to have a strong influence on retrievals of cloud liquid water path and a slight influence on wind speed. Beam-filling effects in the resampled brightness temperatures are shown to be responsible for the large differences between the retrievals using the TMI native resolution and resampled brightness temperatures. Synthetic retrievals are performed to test the sensitivity of the retrieved parameters to beam-filling effects in the resampling of each of the different channels. Beam-filling effects due to the convolution of the 85-GHz channels are shown to be the largest contributor to differences in retrieved cloud liquid water path. Differences in retrieved wind speeds are found to be a combination of effects from deconvolving the 10-GHz brightness temperatures and compensation effects due to the lower liquid water path being retrieved by the high-frequency channels. The influence of beam-filling effects on daily and monthly averages of cloud liquid water path is also explored. Results show that space–time averaging of cloud liquid water path cannot fully compensate for the beam-filling effects and should be considered when using cloud liquid water path data for validation or in climate studies.

Corresponding author address: Anita D. Rapp, CIRES, University of Colorado, and NOAA/ESRL, 325 Broadway, Boulder, CO 80305. Email: anita.d.rapp@noaa.gov

Abstract

How to deal with the different spatial resolutions of multifrequency satellite microwave radiometer measurements is a common problem in retrievals of cloud properties and rainfall. Data convolution and deconvolution is a common approach to resampling the measurements to a single resolution. Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) measurements are resampled to the resolution of the 19-GHz field of view for use in a multifrequency optimal estimation retrieval algorithm of cloud liquid water path, total precipitable water, and wind speed. Resampling the TMI measurements is found to have a strong influence on retrievals of cloud liquid water path and a slight influence on wind speed. Beam-filling effects in the resampled brightness temperatures are shown to be responsible for the large differences between the retrievals using the TMI native resolution and resampled brightness temperatures. Synthetic retrievals are performed to test the sensitivity of the retrieved parameters to beam-filling effects in the resampling of each of the different channels. Beam-filling effects due to the convolution of the 85-GHz channels are shown to be the largest contributor to differences in retrieved cloud liquid water path. Differences in retrieved wind speeds are found to be a combination of effects from deconvolving the 10-GHz brightness temperatures and compensation effects due to the lower liquid water path being retrieved by the high-frequency channels. The influence of beam-filling effects on daily and monthly averages of cloud liquid water path is also explored. Results show that space–time averaging of cloud liquid water path cannot fully compensate for the beam-filling effects and should be considered when using cloud liquid water path data for validation or in climate studies.

Corresponding author address: Anita D. Rapp, CIRES, University of Colorado, and NOAA/ESRL, 325 Broadway, Boulder, CO 80305. Email: anita.d.rapp@noaa.gov

Save
Cover Journal of Applied Meteorology and Climatology
Journal of Applied Meteorology and Climatology

  • Backus, G., and F. Gilbert, 1970: Uniqueness in the inversion of inaccurate gross earth data. Philos. Trans. Roy. Soc. London, A266 , 123–192.

    • Search Google Scholar
    • Export Citation

  • Bremen, L. V., E. Ruprecht, and A. Macke, 2002: Errors in liquid water path retrieval arising from cloud inhomogeneities: The beam-filling effect. Meteor. Z., 11 , 13–19.

    • Search Google Scholar
    • Export Citation

  • Chiu, L. S., G. R. North, D. A. Short, and A. McConnell, 1990: Rain estimation from satellites: Effect of finite field of view. J. Geophys. Res., 95 , 2177–2185.

    • Search Google Scholar
    • Export Citation

  • Conrath, B. J., 1972: Vertical resolution of temperature profiles obtained from remote radiation measurements. J. Atmos. Sci., 29 , 1262–1271.

    • Search Google Scholar
    • Export Citation

  • Conrath, B. J., 1977: Backus-Gilbert theory and its application to retrieval of ozone and temperature profiles. Inversion Methods in Atmospheric Remote Sounding, A. Deepak, Ed., Academic Press, 620 pp.

    • Search Google Scholar
    • Export Citation

  • Elsaesser, G. S., and C. D. Kummerow, 2008: Towards a fully parametric retrieval of the nonraining parameters over the global oceans. J. Appl. Meteor. Climatol., 47 , 1599–1618.

    • Search Google Scholar
    • Export Citation

  • Farrar, M. R., and E. A. Smith, 1992: Spatial-resolution enhancement of terresterial features using deconvolved SSM/I microwave brightness temperatures. IEEE Trans. Geosci. Remote Sens, 30 , 349–355.

    • Search Google Scholar
    • Export Citation

  • Graves, E. G., 1993: A model for the beam-filling effect associated with the microwave retrieval of rain. J. Atmos. Oceanic Technol., 10 , 5–14.

    • Search Google Scholar
    • Export Citation

  • Greenwald, T. J., S. A. Christopher, and J. Chou, 1997: Cloud liquid water path comparisons from passive microwave and solar reflectance satellite measurements: Assessment of sub-field-of-view cloud effects in microwave retrievals. J. Geophys. Res., 102 , 19585–19596.

    • Search Google Scholar
    • Export Citation

  • Ha, E., and G. R. North, 1995: Model studies of the beam-filling error for rain-rate retrieval with microwave radiometers. J. Atmos. Oceanic Technol., 12 , 268–281.

    • Search Google Scholar
    • Export Citation

  • Hollinger, J., R. Lo, G. Poe, R. Savage, and J. Pierce, 1987: Special Sensor Microwave/Imager user’s guide. Naval Research Laboratory Tech. Rep., 177 pp.

    • Search Google Scholar
    • Export Citation

  • Kummerow, C., 1998: Beamfilling errors in passive microwave rainfall retrievals. J. Appl. Meteor., 37 , 356–370.

  • Kummerow, C., W. Barnes, T. Kozu, J. Shiue, and J. Simpson, 1998: The tropical rainfall measuring mission (TRMM) sensor package. J. Atmos. Oceanic Technol., 15 , 808–816.

    • Search Google Scholar
    • Export Citation

  • Long, D. G., and D. L. Daum, 1998: Spatial resolution enhancement of SSM/I data. IEEE Trans. Geosci. Remote Sens., 36 , 407–417.

  • Melitta, J., and K. B. Katsaros, 1995: Using coincident multispectral satellite data to assess the accuracy of special sensor microwave imager liquid water path estimates. J. Geophys. Res., 100 , 16333–16339.

    • Search Google Scholar
    • Export Citation

  • Post, M. J., 1975: Limitations of cloud droplet size distribution by Backus–Gilbert inversion of optical scattering data. J. Opt. Soc. Amer., 5 , 483–486.

    • Search Google Scholar
    • Export Citation

  • Rapp, A. D., C. Kummerow, and G. Elsaesser, 2009: A combined multisensor optimal estimation retrieval algorithm for oceanic warm rain clouds. J. Appl. Meteor. Climatol., in press.

    • Search Google Scholar
    • Export Citation

  • Robinson, W., C. Kummerow, and W. S. Olson, 1992: A technique for matching the resolution of microwave measurements from the SSM/I instrument. IEEE Trans. Geosci. Remote Sens., 30 , 419–429.

    • Search Google Scholar
    • Export Citation

  • Short, D. A., and G. R. North, 1990: The beam filling error in Nimbus-5 ESMR observations of GATE rainfall. J. Geophys. Res., 95 , 2187–2193.

    • Search Google Scholar
    • Export Citation

  • Stogryn, A., 1978: Estimates of brightness temperatures from scanning radiometer data. IEEE Trans. Antennas Propag., AP-26 , 720–726.

  • Westwater, E. R., and A. Cohen, 1973: Application of Backus-Gilbert inversion technique to determination of aerosol size distributions from optical scattering measurements. Appl. Opt., 12 , 1340–1348.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 201 57 10
PDF Downloads 92 42 0