Improving representation of convective transport for scale-aware parameterization: 1. Convection and cloud properties simulated with spectral bin and bulk microphysics

TitleImproving representation of convective transport for scale-aware parameterization: 1. Convection and cloud properties simulated with spectral bin and bulk microphysics
Publication TypeJournal Article
Year of Publication2015
AuthorsFan J.W, Liu Y.C, Xu K.M, North K., Collis S., Dong X.Q, Zhang GJ, Chen Q., Kollias P., Ghan SJ
JournalJournal of Geophysical Research-Atmospheres
Volume120
Pagination3485-3509
Date Published2015/04
Type of ArticleArticle
ISBN Number2169-897X
Accession NumberWOS:000354826100028
Keywordsbin and bulk microphysics; cloud-resolving; cumulus ensembles; cumulus parameterization; Deep convection; explicit simulation; intensity; mass flux; mesoscale model mm5; models; part i; precipitation; resolving models; scale aware; sensitivity; squall line
Abstract

The ultimate goal of this study is to improve the representation of convective transport by cumulus parameterization for mesoscale and climate models. As Part 1 of the study, we perform extensive evaluations of cloud-resolving simulations of a squall line and mesoscale convective complexes in midlatitude continent and tropical regions using the Weather Research and Forecasting model with spectral bin microphysics (SBM) and with two double-moment bulk microphysics schemes: a modified Morrison (MOR) and Milbrandt and Yau (MY2). Compared to observations, in general, SBM gives better simulations of precipitation and vertical velocity of convective cores than MOR and MY2 and therefore will be used for analysis of scale dependence of eddy transport in Part 2. The common features of the simulations for all convective systems are (1) the model tends to overestimate convection intensity in the middle and upper troposphere, but SBM can alleviate much of the overestimation and reproduce the observed convection intensity well; (2) the model greatly overestimates Z(e) in convective cores, especially for the weak updraft velocity; and (3) the model performs better for midlatitude convective systems than the tropical system. The modeled mass fluxes of the midlatitude systems are not sensitive to microphysics schemes but are very sensitive for the tropical case indicating strong microphysics modification to convection. Cloud microphysical measurements of rain, snow, and graupel in convective cores will be critically important to further elucidate issues within cloud microphysics schemes.

DOI10.1002/2014jd022142
Student Publication: 
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