A Novel Ice-Cloud Retrieval Algorithm Based on the Millimeter-Wave Imaging Radiometer (MIR) 150- and 220-GHz Channels

Merritt N. Deeter National Center for Atmospheric Research, Boulder, Colorado

Search for other papers by Merritt N. Deeter in
Current site
Google Scholar
PubMed
Close
and
K. Franklin Evans Program in Atmospheric and Oceanic Sciences, University of Colorado, Boulder, Colorado

Search for other papers by K. Franklin Evans in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

A novel microwave technique for simultaneously retrieving cirrus ice water path (IWP) and characteristic ice particle size is described. The retrieval algorithm exploits radiance measurements made at 150 and 220 GHz by the airborne Millimeter-Wave Imaging Radiometer (MIR). Other MIR channels additionally are used to test for the presence of liquid clouds and precipitation, which otherwise would have a contaminating effect on the retrievals. Forward radiative transfer modeling was used to generate a two-dimensional retrieval table in which brightness-temperature depressions (relative to clear-sky values) for both microwave channels were recorded as functions of IWP and characteristic particle size for gamma distributions of ice particles. Retrieval errors due to particle shape, size distribution, clear-sky water vapor variability, cirrus-cloud altitude variability, and instrument noise were estimated using Monte Carlo analysis. Particle shape uncertainty is believed to be the dominant source of retrieval error. The technique is demonstrated using MIR data recorded on the National Aeronautics and Space Administration ER-2 aircraft during the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment experiment in the tropical western Pacific Ocean in 1993. The retrieval technique with MIR data is suited only to high-IWP clouds with large ice particles, such as thick frontal cirrus and convective anvils. The general methodology, however, is applicable to higher frequencies that have greatly increased sensitivity to thinner cirrus.

Corresponding author address: Merritt N. Deeter, National Center for Atmospheric Research, FL4, Suite 275, Boulder, CO 80301-1371.

mnd@eos.ucar.edu

Abstract

A novel microwave technique for simultaneously retrieving cirrus ice water path (IWP) and characteristic ice particle size is described. The retrieval algorithm exploits radiance measurements made at 150 and 220 GHz by the airborne Millimeter-Wave Imaging Radiometer (MIR). Other MIR channels additionally are used to test for the presence of liquid clouds and precipitation, which otherwise would have a contaminating effect on the retrievals. Forward radiative transfer modeling was used to generate a two-dimensional retrieval table in which brightness-temperature depressions (relative to clear-sky values) for both microwave channels were recorded as functions of IWP and characteristic particle size for gamma distributions of ice particles. Retrieval errors due to particle shape, size distribution, clear-sky water vapor variability, cirrus-cloud altitude variability, and instrument noise were estimated using Monte Carlo analysis. Particle shape uncertainty is believed to be the dominant source of retrieval error. The technique is demonstrated using MIR data recorded on the National Aeronautics and Space Administration ER-2 aircraft during the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment experiment in the tropical western Pacific Ocean in 1993. The retrieval technique with MIR data is suited only to high-IWP clouds with large ice particles, such as thick frontal cirrus and convective anvils. The general methodology, however, is applicable to higher frequencies that have greatly increased sensitivity to thinner cirrus.

Corresponding author address: Merritt N. Deeter, National Center for Atmospheric Research, FL4, Suite 275, Boulder, CO 80301-1371.

mnd@eos.ucar.edu

Save
  • Burns, B. A., X. Wu, and G. R. Diak, 1997: Effects of precipitation and cloud ice on brightness temperatures in AMSU moisture channels. IEEE Trans. Geosci. Remote Sens.,35, 1429–1437.

  • Deeter, M. N., and K. F. Evans, 1998: A hybrid Eddington–single scattering radiative transfer model for computing radiances from thermally emitting atmospheres. J. Quant. Spectrosc. Radiat. Transfer,60, 635–648.

  • Evans, K. F., and G. L. Stephens, 1995a: Microwave radiative transfer through clouds composed of realistically shaped ice crystals. Part I: Single-scattering properties. J. Atmos. Sci.,52, 2041–2057.

  • Evans, K. F., and G. L. Stephens, 1995b: Microwave radiative transfer through clouds composed of realistically shaped ice crystals. Part II: Remote sensing of ice clouds. J. Atmos. Sci.,52, 2058–2072.

  • Evans, K. F., S. J. Walter, A. J. Heymsfield, and M. N. Deeter, 1998: Modeling of submillimeter passive remote sensing of cirrus clouds. J. Appl. Meteor.,37, 184–205.

  • Gasiewski, A. J., 1992: Numerical sensitivity analysis of passive EHF and SMMW channels to tropospheric water vapor, clouds, and precipitation. IEEE Trans. Geosci. Remote Sens.,30, 859–870.

  • King, M. D., and Coauthors, 1996: Airborne scanning spectrometer for remote sensing of cloud, aerosol, water vapor, and surface properties. J. Atmos. Oceanic Technol.,13, 777–793.

  • Kosarev, A. L., and I. P. Mazin, 1989: Empirical model of physical structure of the upper level clouds of the middle latitudes. Radiation Properties of Cirrus Clouds, E. Feigelson, Ed., Nauka, 29–52.

  • Liebe, H. J., 1989: MPM—An atmospheric millimeter-wave propagation model. J. Infrared Millimeter Waves,10, 631–650.

  • Liebe, H. J., G. A. Hufford, and T. Manabe, 1991: A model for the complex permittivity of water at frequencies below 1 THz. J. Infrared Millimeter Waves,12, 659–675.

  • Liou, K.-N., 1986: Influence of cirrus clouds on weather and climate processes: A global perspective. Mon. Wea. Rev.,114, 1167–1199.

  • Liu, G., and J. A. Curry, 1998: Remote sensing of ice water characteristics in tropical clouds using aircraft microwave measurements. J. Appl. Meteor.,37, 337–355.

  • Mapes, B. E., and P. Zuidema, 1996: Radiative–dynamical consequences of dry tongues in the tropical troposphere. J. Atmos. Sci.,53, 620–638.

  • McFarquhar, G. M., and A. J. Heymsfield, 1996: Microphysical characteristics of three anvils sampled during the Central Equatorial Pacific Experiment. J. Atmos. Sci.,53, 2401–2423.

  • Minnis, P., P. W. Heck, and D. F. Young, 1993: Inference of cirrus cloud properties using satellite-observed visible and infrared radiances. Part II: Verification of theoretical cirrus radiative properties. J. Atmos. Sci.,50, 105–1322.

  • Ou, S. C., K.-N. Liou, W. M. Gooch, and Y. Takano, 1993: Remote sensing of cirrus cloud parameters using Advanced Very-High-Resolution Radiometer 3.7- and 10.9-μm channels. Appl. Opt.,32, 2171–2180.

  • Racette, P., R. F. Adler, J. R. Wang, A. J. Gasiewski, D. M. Jackson, and D. S. Zacharias, 1996: An airborne millimeter-wave imaging radiometer for cloud, precipitation, and atmospheric water vapor studies. J. Atmos. Oceanic Technol.,13, 610–618.

  • Spencer, R. W., H. M. Goodman, and R. E. Hood, 1989: Precipitation retrieval over land and ocean with the SSM/I: Identification and characteristics of the scattering signal. J. Atmos. Oceanic Technol.,6, 254–273.

  • Wang, J. R., P. Racette, J. D. Spinhirne, K. F. Evans, and W. D. Hart, 1998: Observations of cirrus clouds with airborne MIR, CLS, and MAS during SUCCESS. Geophys. Res. Lett.,25, 1145–1148.

  • Webster, P. J., and R. Lukas, 1992: TOGA COARE: The Coupled Ocean–Atmosphere Response Experiment. Bull. Amer. Meteor. Soc.,73, 1377–1416.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 111 40 4
PDF Downloads 70 21 2