Regional Climate Modeling over the Maritime Continent. Part II: New Parameterization for Autoconversion of Convective Rainfall
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Eltahir_Regional climate.pdf
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Author(s)
Eltahir, Elfatih A. B.
Gianotti, Rebecca Louise
Date Issued
February 2014
Journal
Journal of Climate
Publisher
American Meteorological Society
Citation
Gianotti, Rebecca L., and Elfatih A. B. Eltahir. “Regional Climate Modeling over the Maritime Continent. Part II: New Parameterization for Autoconversion of Convective Rainfall.” J. Climate 27, no. 4 (February 2014): 1504–1523. © 2014 American Meteorological Society
Version
Final published version
Abstract
This paper describes a new method for parameterizing the conversion of convective cloud liquid water to rainfall (“autoconversion”) that can be used within large-scale climate models, and evaluates the new method using the Regional Climate Model, version 3 (RegCM3), coupled to the land surface scheme Integrated Biosphere Simulator (IBIS). The new method is derived from observed distributions of cloud water content and is constrained by observations of cloud droplet characteristics and climatological rainfall intensity. This new method explicitly accounts for subgrid variability with respect to cloud water density and is independent of model resolution, making it generally applicable for large-scale climate models. This work builds on the development of a new parameterization method for convective cloud fraction, which was described in Part I.
imulations over the Maritime Continent using the Emanuel convection scheme show significant improvement in model performance, not only with respect to convective rainfall but also in shortwave radiation, net radiation, and turbulent surface fluxes of latent and sensible heat, without any additional modifications made to the simulation of those variables. Model improvements are demonstrated over a 19-yr validation period as well as a shorter 4-yr evaluation. Model performance with the Grell convection scheme is not similarly improved and reasons for this outcome are discussed. This work illustrates the importance of representing observed subgrid-scale variability in diurnally varying convective processes for simulations of the Maritime Continent region.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Parsons Laboratory for Environmental Science and Engineering (Massachusetts Institute of Technology)
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DOI of Published Version
https://doi.org/10.1175/jcli-d-13-00171.1
