Two- and Three-Dimensional Cloud-Resolving Model Simulations of the Mesoscale Enhancement of Surface Heat Fluxes by Precipitating Deep Convection

• Published in: Journal of climate Vol. 19; no. 1; pp. 139 - 149
• Main Authors: Wu, Xiaoqing, Guimond, Stephen
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.01.2006
• Subjects: Atmosphere; Climate; Clouds; Convection; Convection clouds; Earth, ocean, space; Exact sciences and technology; External geophysics; Fluctuations; General circulation models; Latent heat; Meteorology; Other topics in atmospheric geophysics; Parameterization; Physics of the oceans; Precipitation; Sea-air exchange processes; Sensible heat; Togas; Two dimensional modeling; Vertical air currents; Wind velocity; Equatorial Pacific; Latent heat; Sensible heat; General circulation models; atmospheric precipitation; air-sea interface; Convective cloud; digital simulation; Parameterization; Ocean-atmosphere model; Mesoscale; three-dimensional models; two-dimensional models; Pacific Ocean; heat transfer
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/jcl3610.1

Two-dimensional (2D) and three-dimensional (3D) cloud-resolving model (CRM) simulations are conducted to quantify the enhancement of surface sensible and latent heat fluxes by tropical precipitating cloud systems for 20 days (10–30 December 1992) during the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE). The mesoscale enhancement appears to be analogous across both 2D and 3D CRMs, with the enhancement for the sensible heat flux accounting for 17% of the total flux for each model and the enhancement for the latent heat flux representing 18% and 16% of the total flux for 2D and 3D CRMs, respectively. The convection-induced gustiness is mainly responsible for the enhancement observed in each model simulation. The parameterization schemes of the mesoscale enhancement by the gustiness in terms of convective updraft, downdraft, and precipitation, respectively, are examined using each version of the CRM. The scheme utilizing the precipitation was found to yield the most desirable estimations of the mean fluxes with the smallest rms error. The results together with previous findings from other studies suggest that the mesoscale enhancement of surface heat fluxes by the precipitating deep convection is a subgrid process apparent across various CRMs and is imperative to incorporate into general circulation models (GCMs) for improved climate simulation.