Separating Cloud and Drizzle Radar Moments during Precipitation Onset Using Doppler Spectra

Edward P. Luke Atmospheric Sciences Division, Brookhaven National Laboratory, Upton, New York

Search for other papers by Edward P. Luke in
Current site
Google Scholar
PubMed
Close
and
Pavlos Kollias Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, Quebec, Canada

Search for other papers by Pavlos Kollias in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The retrieval of cloud, drizzle, and turbulence parameters using radar Doppler spectra is challenged by the convolution of microphysical and dynamical influences and the overall uncertainty introduced by turbulence. A new technique that utilizes recorded radar Doppler spectra from profiling cloud radars is presented here. The technique applies to areas in clouds where drizzle is initially produced by the autoconversion process and is detected by a positive skewness in the radar Doppler spectrum. Using the Gaussian-shape property of cloud Doppler spectra, the cloud-only radar Doppler spectrum is estimated and used to separate the cloud and drizzle contributions. Once separated, the cloud spectral peak can be used to retrieve vertical air motion and eddy dissipation rates, while the drizzle peak can be used to estimate the three radar moments of the drizzle particle size distribution. The technique works for nearly 50% of spectra found near cloud top, with efficacy diminishing to roughly 15% of spectra near cloud base. The approach has been tested on a large dataset collected in the Azores during the Atmospheric Radiation Measurement Program (ARM) Mobile Facility deployment on Graciosa Island from May 2009 through December 2010. Validation of the proposed technique is achieved using the cloud base as a natural boundary between radar Doppler spectra with and without cloud droplets. The retrieval algorithm has the potential to characterize the dynamical and microphysical conditions at cloud scale during the transition from cloud to precipitation. This has significant implications for improving the understanding of drizzle onset in liquid clouds and for improving model parameterization schemes of autoconversion of cloud water into drizzle.

Corresponding author address: Edward P. Luke, Atmospheric Sciences Division, Brookhaven National Laboratory, Bldg. 490D, Bell Ave., Upton, NY 11973. E-mail: eluke@bnl.gov

Abstract

The retrieval of cloud, drizzle, and turbulence parameters using radar Doppler spectra is challenged by the convolution of microphysical and dynamical influences and the overall uncertainty introduced by turbulence. A new technique that utilizes recorded radar Doppler spectra from profiling cloud radars is presented here. The technique applies to areas in clouds where drizzle is initially produced by the autoconversion process and is detected by a positive skewness in the radar Doppler spectrum. Using the Gaussian-shape property of cloud Doppler spectra, the cloud-only radar Doppler spectrum is estimated and used to separate the cloud and drizzle contributions. Once separated, the cloud spectral peak can be used to retrieve vertical air motion and eddy dissipation rates, while the drizzle peak can be used to estimate the three radar moments of the drizzle particle size distribution. The technique works for nearly 50% of spectra found near cloud top, with efficacy diminishing to roughly 15% of spectra near cloud base. The approach has been tested on a large dataset collected in the Azores during the Atmospheric Radiation Measurement Program (ARM) Mobile Facility deployment on Graciosa Island from May 2009 through December 2010. Validation of the proposed technique is achieved using the cloud base as a natural boundary between radar Doppler spectra with and without cloud droplets. The retrieval algorithm has the potential to characterize the dynamical and microphysical conditions at cloud scale during the transition from cloud to precipitation. This has significant implications for improving the understanding of drizzle onset in liquid clouds and for improving model parameterization schemes of autoconversion of cloud water into drizzle.

Corresponding author address: Edward P. Luke, Atmospheric Sciences Division, Brookhaven National Laboratory, Bldg. 490D, Bell Ave., Upton, NY 11973. E-mail: eluke@bnl.gov
Save
  • Atlas, D., Srivastava R. S. , and Sekhon R. S. , 1973: Doppler radar characteristics of precipitation at vertical incidence. Rev. Geophys. Space Phys., 11, 135.

    • Search Google Scholar
    • Export Citation
  • Babb, D. M., Verlinde J. , and Albrecht B. A. , 1999: Retrieval of cloud microphysical parameters from 94-GHz radar Doppler power spectra. J. Atmos. Oceanic Technol., 16, 489503.

    • Search Google Scholar
    • Export Citation
  • Battan, L. J., 1964: Some observations of vertical velocities and precipitation sizes in a thunderstorm. J. Appl. Meteor., 3, 415420.

    • Search Google Scholar
    • Export Citation
  • Brenguier, J. L., and Wood R. , 2009: Observational strategies from the micro to meso scale. Clouds in the Perturbed Climate System: Their Relationship to Energy Balance, Atmospheric Dynamics, and Precipitation, J. Heintzenberg and R. J. Charlson, Eds., MIT Press, 487–510.

  • Delanoë, J., Protat A. , Bouniol D. , Heymsfield A. , Bansemer A. , and Brown P. , 2007: The characterization of ice cloud properties from Doppler radar measurements. J. Appl. Meteor. Climatol., 46, 16821698.

    • Search Google Scholar
    • Export Citation
  • Deng, M., and Mace G. G. , 2006: Cirrus microphysical properties and air motion statistics using cloud radar Doppler moments. Part I: Algorithm description. J. Appl. Meteor. Climatol., 45, 16901709.

    • Search Google Scholar
    • Export Citation
  • Doviak, R., and Zrnić D. , 1993: Doppler Radar and Weather Observations. 2nd ed. Academic Press, 458 pp.

  • Frisch, A. S., Fairall C. W. , and Snider J. B. , 1995: Measurement of stratus cloud and drizzle parameters in ASTEX with a Kα-band Doppler radar and microwave radiometer. J. Atmos. Sci., 52, 27882799.

    • Search Google Scholar
    • Export Citation
  • Giangrande, S. E., Babb D. M. , and Verlinde J. , 2001: Processing millimeter wave profiler radar spectra. J. Atmos. Oceanic Technol., 18, 15771583.

    • Search Google Scholar
    • Export Citation
  • Giangrande, S. E., Luke E. P. , and Kollias P. , 2010: Automated retrievals of precipitation parameters using non-Rayleigh scattering at 95 GHz. J. Atmos. Oceanic Technol., 27, 14901503.

    • Search Google Scholar
    • Export Citation
  • Gossard, E. E., 1994: Measurements of cloud droplet size spectra by Doppler radar. J. Atmos. Oceanic Technol., 11, 712726.

  • Gossard, E. E., Snider J. B. , Clothiaux E. E. , Martner B. , Gibson J. S. , Kropfli R. A. , and Frisch A. S. , 1997: The potential of 8-mm radars for remotely sensing cloud drop size distributions. J. Atmos. Oceanic Technol., 14, 7687.

    • Search Google Scholar
    • Export Citation
  • Hauser, D., and Amayenc P. , 1981: A new method for deducing hydrometeor-size distributions and vertical air motions from Doppler radar measurements at vertical incidence. J. Appl. Meteor., 20, 547555.

    • Search Google Scholar
    • Export Citation
  • Hildebrand, P. H., and Sekhon R. S. , 1974: Objective determination of the noise level in Doppler spectra. J. Appl. Meteor., 13, 808811.

    • Search Google Scholar
    • Export Citation
  • Kollias, P., and Albrecht B. A. , 2000: The turbulence structure in a continental stratocumulus cloud from millimeter wavelength radar observations. J. Atmos. Sci., 57, 24172434.

    • Search Google Scholar
    • Export Citation
  • Kollias, P., Albrecht B. A. , Lhermitte R. , and Savtchenko A. , 2001: Radar observations of updrafts, downdrafts, and turbulence in fair-weather cumuli. J. Atmos. Sci., 58, 17501766.

    • Search Google Scholar
    • Export Citation
  • Kollias, P., Albrecht B. A. , and Marks F. D. Jr., 2002: Why Mie? Accurate observations of vertical air velocities and rain drops using a cloud radar. Bull. Amer. Meteor. Soc., 83, 14711483.

    • Search Google Scholar
    • Export Citation
  • Kollias, P., Clothiaux E. E. , Miller M. A. , Albrecht B. A. , Stephens G. L. , and Ackerman T. P. , 2007: Millimeter-wavelength radars: New frontier in atmospheric cloud and precipitation research. Bull. Amer. Meteor. Soc., 88, 16081624.

    • Search Google Scholar
    • Export Citation
  • Kollias, P., Remillard J. , Luke E. , and Szyrmer W. , 2011a: Cloud radar Doppler spectra in drizzling stratiform clouds: 1. Forward modeling and remote sensing applications. J. Geophys. Res., 116, D13201, doi:10.1029/2010JD015237.

    • Search Google Scholar
    • Export Citation
  • Kollias, P., Szyrmer W. , Remillard J. , and Luke E. , 2011b: Cloud radar Doppler spectra in drizzling stratiform clouds: 2. Observations and microphysical modeling of drizzle evolution. J. Geophys. Res., 116, D13203, doi:10.1029/2010JD015238.

    • Search Google Scholar
    • Export Citation
  • Lhermitte, R., 1988: Observations of rain at vertical incidence with a 94 GHz doppler radar: An insight on Mie scattering. Geophys. Res. Lett., 15, 11251128.

    • Search Google Scholar
    • Export Citation
  • Luke, E. P., Kollias P. , and Shupe M. D. , 2010: Detection of supercooled liquid in mixed-phase clouds using radar Doppler spectra. J. Geophys. Res., 115, D19201, doi:10.1029/2009JD012884.

    • Search Google Scholar
    • Export Citation
  • Rogers, R. R., and Pilié R. J. , 1962: Radar measurements of drop-size distributions. J. Atmos. Sci., 19, 503506.

  • Rogers, R. R., Ecklund W. L. , Carter D. A. , Gage K. S. , and Ethier S. A. , 1993: Research applications of a boundary-layer wind profiler. Bull. Amer. Meteor. Soc., 74, 567580.

    • Search Google Scholar
    • Export Citation
  • Shupe, M. D., Kollias P. , Matrosov S. Y. , and Schneider T. L. , 2004: Deriving mixed-phase cloud properties from Doppler radar spectra. J. Atmos. Oceanic Technol., 21, 660670.

    • Search Google Scholar
    • Export Citation
  • Wakasugi, K., Mizutani A. , Matsuo M. , Fukao S. , and Kato S. , 1986: A direct method for deriving drop-size distribution and vertical air velocities from VHF Doppler radar spectra. J. Atmos. Oceanic Technol., 3, 623629.

    • Search Google Scholar
    • Export Citation
  • Williams, C. R., Ecklund W. L. , and Gage K. S. , 1995: Classification of precipitating clouds in the tropics using 915-MHz wind profilers. J. Atmos. Oceanic Technol., 12, 9961012.

    • Search Google Scholar
    • Export Citation
  • Williams, C. R., Ecklund W. L. , Johnston P. E. , and Gage K. S. , 2000: Cluster analysis techniques to separate air motion and hydrometeors in vertical incident profiler observations. J. Atmos. Oceanic Technol., 17, 949962.

    • Search Google Scholar
    • Export Citation
  • Zrnić, D. S., 1975: Simulation of weatherlike Doppler spectra and signals. J. Appl. Meteor., 14, 619620.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 787 304 34
PDF Downloads 517 135 13