Novel Evaluation of Cloud Model Microphysical Fields using Polarimetric Radar Observations
Poster PDF
Authors
Steven A Rutledge — Colorado State University
Wei-Kuo Tao — NASA - Goddard Space Flight Center
Toshihisa Matsui — Earth System Science Interdisciplinary Center at University of Maryland
Brenda Dolan — Colorado State University
Taka Iguchi — University of Maryland College Park
Barnum Julie — Colorado State University
Category
Microphysics (cloud, aerosol and/or precipitation)
Description
The goal of this work is to carefully evaluate cloud microphysical parameterizations leading to improvements in simulating kinematics and microphysical processes within tropical and mid-latitude deep convection. We have simulated a number of cases from two past DOE field projects. Using the NASA-Unified WRF model (NU-WRF), two prime cases from TWP-ICE (N. Australia) have been simulated, 21-26 January and 15-20 February, 2006. These cases represent examples of monsoon and break period convection, respectively. For MC3E (Oklahoma), a range of cases have been simulated including 1 May (widespread stratiform rain with embedded convection), 20 May (propagating squall line), and 23 May, 2011 (strong isolated convective cell). Multiple simulations for each case have been carried out, using selected microphysical parameterizations including the Goddard 3-ICE (single-moment) scheme, Goddard 4-ICE (single-moment) scheme, Morrison double-moment scheme with graupel and the Morrison double-moment scheme with hail. Currently, we are performing another full set of simulations using the HUCM spectral bin microphysics package to afford a detailed comparison between bulk and bin microphysics.
In the past year a substantial effort has been devoted to developing POLARRIS. POLARRIS is a comprehensive package that calculates the full range of polarimetric variables (at multiple frequencies), using the model-derived microphysical fields as input. The polarimetric variables output by POLARRIS are then input to an improved version of the CSU Hydrometeor Identification Algorithm. This algorithm outputs the distribution of hydrometeor types within the model domain. Using CFAD and other techniques, the model-derived HID fields are compared to the observed HID fields, which are based on actual polarimetric radar observations. POLARRIS has been developed at S-, C-, and X-bands to use the full suite of meteorological radars available in the above field projects. To support the POLARRIS work, a number of studies have been done to examine the sensitivity of the polarimetric variables to input quantities such as particle density, oblateness, and canting angle distributions. Examples of model and observed fields will be presented along with selected kinematic comparisons between the model kinematic fields and those retrieved from dual-Doppler observations.
