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WRF-SBM Simulations of Melting-Layer Structure in Mixed-Phase Precipitation Events Observed during LPVEx

Iguchi, Takamichi; Matsui, Toshihisa; Tao, Wei-Kuo; Khain, Alexander P.; Phillips, Vaughan LU ; Kidd, Chris; L'Ecuyer, Tristan; Braun, Scott A. and Hou, Arthur (2014) In Journal of Applied Meteorology and Climatology 53(12). p.2710-2731
Abstract
Two mixed-phase precipitation events were observed on 21 September and 20 October 2010 over the southern part of Finland during the Light Precipitation Validation Experiment (LPVEx). These events have been simulated using the Weather Research and Forecasting Model coupled with spectral bin microphysics (WRF-SBM). The detailed ice-melting scheme with prognosis of the liquid water fraction during melting enables explicit simulation of microphysical properties in the melting layer. First, the simulations have been compared with C-band 3D radar measurements for the purpose of evaluating the overall profiles of cloud and precipitation. The simulation has some artificial convective patterns and errors in the forecast displacement of the... (More)
Two mixed-phase precipitation events were observed on 21 September and 20 October 2010 over the southern part of Finland during the Light Precipitation Validation Experiment (LPVEx). These events have been simulated using the Weather Research and Forecasting Model coupled with spectral bin microphysics (WRF-SBM). The detailed ice-melting scheme with prognosis of the liquid water fraction during melting enables explicit simulation of microphysical properties in the melting layer. First, the simulations have been compared with C-band 3D radar measurements for the purpose of evaluating the overall profiles of cloud and precipitation. The simulation has some artificial convective patterns and errors in the forecast displacement of the precipitation system. The overall overestimation of reflectivity is consistent with a bias toward the range characterized by large-diameter droplets in the surface drop size distribution. Second, the structure of the melting bands has been evaluated against vertically pointing K-band radar measurements. A peak in reflectivity and a gradual change in Doppler velocity are observed and similarly simulated in the common temperature range from approximately 0 degrees to 3 degrees C. The effectiveness of the time-dependent melting scheme has been justified by intercomparison with a corresponding simulation using an instantaneous melting scheme. A weakness of the new melting scheme is that melting particles having high liquid water fractions on the order of 80%-90% cannot be simulated. This situation may cause underestimation of radar reflectivity in the melting layer because of the assumptions of melting-particle structure used to calculate the scattering properties. (Less)
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organization
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type
Contribution to journal
publication status
published
subject
in
Journal of Applied Meteorology and Climatology
volume
53
issue
12
pages
2710 - 2731
publisher
Amer Meteorological Soc
external identifiers
  • wos:000346284300006
  • scopus:84928334571
ISSN
1558-8424
DOI
10.1175/JAMC-D-13-0334.1
project
MERGE
language
English
LU publication?
yes
id
2b2e4e01-21c8-4019-9495-d5c230406f3a (old id 4944687)
date added to LUP
2015-01-28 11:54:51
date last changed
2017-11-12 03:47:46
@article{2b2e4e01-21c8-4019-9495-d5c230406f3a,
  abstract     = {Two mixed-phase precipitation events were observed on 21 September and 20 October 2010 over the southern part of Finland during the Light Precipitation Validation Experiment (LPVEx). These events have been simulated using the Weather Research and Forecasting Model coupled with spectral bin microphysics (WRF-SBM). The detailed ice-melting scheme with prognosis of the liquid water fraction during melting enables explicit simulation of microphysical properties in the melting layer. First, the simulations have been compared with C-band 3D radar measurements for the purpose of evaluating the overall profiles of cloud and precipitation. The simulation has some artificial convective patterns and errors in the forecast displacement of the precipitation system. The overall overestimation of reflectivity is consistent with a bias toward the range characterized by large-diameter droplets in the surface drop size distribution. Second, the structure of the melting bands has been evaluated against vertically pointing K-band radar measurements. A peak in reflectivity and a gradual change in Doppler velocity are observed and similarly simulated in the common temperature range from approximately 0 degrees to 3 degrees C. The effectiveness of the time-dependent melting scheme has been justified by intercomparison with a corresponding simulation using an instantaneous melting scheme. A weakness of the new melting scheme is that melting particles having high liquid water fractions on the order of 80%-90% cannot be simulated. This situation may cause underestimation of radar reflectivity in the melting layer because of the assumptions of melting-particle structure used to calculate the scattering properties.},
  author       = {Iguchi, Takamichi and Matsui, Toshihisa and Tao, Wei-Kuo and Khain, Alexander P. and Phillips, Vaughan and Kidd, Chris and L'Ecuyer, Tristan and Braun, Scott A. and Hou, Arthur},
  issn         = {1558-8424},
  language     = {eng},
  number       = {12},
  pages        = {2710--2731},
  publisher    = {Amer Meteorological Soc},
  series       = {Journal of Applied Meteorology and Climatology},
  title        = {WRF-SBM Simulations of Melting-Layer Structure in Mixed-Phase Precipitation Events Observed during LPVEx},
  url          = {http://dx.doi.org/10.1175/JAMC-D-13-0334.1},
  volume       = {53},
  year         = {2014},
}