Data from the undisturbed period of the Rain in Cumulus over the Ocean (RICO) field study are used to create a test case for large-eddy simulations of shallow, precipitating, trade-wind cumulus. Measurements upon which the test case are based are aug-mented by a regional scale downscaling of meteorological analyses so as to provide forcing data consistent with the measurements. Twelve large-eddy simulations, with a wide range of microphysical representations, are compared to each other, and to independent measurements during RICO. The ensemble average of the simulations plausibly reproduces many features of the observed clouds, including the vertical structure of cloud fraction, profiles of cloud and rain water, and to a lesser degree the population density of rain drops. The simulations do show considerable departures from one another in the representation of the cloud microphysical structure and the ensuant surface precipitation rates. There is a robust tendency for simulations that develop rain to produce a shallower, somewhat more unstable cloud layer. Relations between cloud cover and precipitation are ambiguous.
Digital Commons Citation
vanZanten, Margreet C; Stevens, Bjorn; Nuijens, Louise; and Kogan, Y., "Controls On Precipitation And Cloudiness In Simulations Of Trade-Wind Cumulus As Observed During Rico" (2011). Faculty & Staff Scholarship. 959.
vanZanten, Margreet C., Stevens, Bjorn., Nuijens, Louise., Kogan, Y. (2011). Controls On Precipitation And Cloudiness In Simulations Of Trade-Wind Cumulus As Observed During Rico. Journal of Advances in Modeling Earth Systems, 3(2), n/a-n/a. http://doi.org/10.1029/2011MS000056