Cloud-resolving model intercomparison of an MC3E squall line case: Part I—Convective updrafts

Jiwen Fan, Bin Han, Adam Varble, Hugh Morrison, Kirk North, Pavlos Kollias, Baojun Chen, Xiquan Dong, Scott E. Giangrande, Alexander Khain, Yun Lin, Edward Mansell, Jason A. Milbrandt, Ronald Stenz, Gregory Thompson, Yuan Wang

Research output: Contribution to journalArticlepeer-review

99 Scopus citations


An intercomparison study of a midlatitude mesoscale squall line is performed using the Weather Research and Forecasting (WRF) model at 1 km horizontal grid spacing with eight different cloud microphysics schemes to investigate processes that contribute to the large variability in simulated cloud and precipitation properties. All simulations tend to produce a wider area of high radar reflectivity (Ze > 45 dBZ) than observed but a much narrower stratiform area. The magnitude of the virtual potential temperature drop associated with the gust front passage is similar in simulations and observations, while the pressure rise and peak wind speed are smaller than observed, possibly suggesting that simulated cold pools are shallower than observed. Most of the microphysics schemes overestimate vertical velocity and Ze in convective updrafts as compared with observational retrievals. Simulated precipitation rates and updraft velocities have significant variability across the eight schemes, even in this strongly dynamically driven system. Differences in simulated updraft velocity correlate well with differences in simulated buoyancy and low-level vertical perturbation pressure gradient, which appears related to cold pool intensity that is controlled by the evaporation rate. Simulations with stronger updrafts have a more optimal convective state, with stronger cold pools, ambient low-level vertical wind shear, and rear-inflow jets. Updraft velocity variability between schemes is mainly controlled by differences in simulated ice-related processes, which impact the overall latent heating rate, whereas surface rainfall variability increases in no-ice simulations mainly because of scheme differences in collision-coalescence parameterizations.

Original languageEnglish (US)
Pages (from-to)9351-9378
Number of pages28
JournalJournal of Geophysical Research Atmospheres
Issue number17
StatePublished - Sep 16 2017


  • convection
  • microphysics parameterization
  • model intercomparison
  • squall line

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Atmospheric Science
  • Geophysics
  • Space and Planetary Science


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