Statistical comparison of properties of simulated and observed cumulus clouds in the vicinity of Houston during the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS)
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Authors
Jiang, Hongli
Feingold, Graham
Jonsson, Haflidi H.
Lu, Miao-Ling
Chuang, Patrick Y.
Flagan, Richard C.
Seinfeld, John H.
Subjects
Advisors
Date of Issue
2008
Date
2008
Publisher
American Geophysical Union (AGU)
Language
Abstract
We present statistical comparisons of properties of clouds generated by Large Eddy Simulations (LES) with aircraft observations of nonprecipitating, warm cumulus clouds made in the vicinity of Houston, TX during the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), carried out in the summer of 2006. Aircraft data were sampled with the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter airplane. Five flights (days) that are most suitable for studying aerosol-cloud interactions are selected from the 22 flights. The model simulations are initiated with observed environmental profiles. The simulations are used to generate an ensemble of thousands of cumulus clouds for statistically meaningful evaluations. Statistical comparisons focus on the properties of a set of dynamical and thermodynamical variables, sampled either in the cloud or the cloud updraft core. The set of variables includes cloud liquid water content (LWC), number mixing ratio of cloud droplets (Nd), cloud effective radius (re), updraft velocity (w), and the distribution of cloud sizes. In general, good agreement between the simulated and observed clouds is achieved in the normalized frequency distribution functions, the profiles averaged over the cloudy regions, the cross-cloud averages, and the cloud size distributions, despite big differences in sample size between the model output and the aircraft data. Some unresolved differences in frequency distributions of w and possible differences in cloud fraction are noted. These comparisons suggest that the LES is able to successfully generate the cumulus cloud populations that were present during GoMACCS. The extent to which this is true will depend on the specific application.
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Article
Description
The article of record as published may be located at http://dx.doi.org/10.1029/2007JD009304.
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Citation
Journal of Geophysical Research, Vol. 113, D13205
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.