ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-9323-2011 Large-Eddy Simulation of a microburst Anabor V. 1 Rizza U. 1 2 Nascimento E. L. 1 Degrazia G. A. 1 Universidade Federal de Santa Maria, Departamento de Física, Santa Maria, RS, Brazil Institute for Atmospheric Sciences and Climate, ISAC-CNR, Italy 09 09 2011 11 17 9323 9331 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/11/9323/2011/acp-11-9323-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/9323/2011/acp-11-9323-2011.pdf

The three-dimensional structure and evolution of an isolated and stationary microburst are simulated using a time-dependent, high resolution Large-Eddy-Simulation (LES) model. The microburst is initiated by specifying a simplified cooling source at the top of the domain around 2 km a.g.l. that leads to a strong downdraft. Surface winds of the order of 30 m s<sup>−1</sup> were obtained over a region of 500 m radius around the central point of the impinging downdraft, with the simulated microburst lasting for a few minutes. These characteristic length and time scales are consistent with results obtained from numerical simulations of microbursts using cloud-resolving models. The simulated flow replicated some of the principal features of microbursts observed by Doppler radars: in particular, the horizontal spread of strong surface winds and a ring vortex at the leading edge of the cold outflow. In addition to the primary surface outflow, the simulation also generated a secondary surge of strong winds that appears to represent a pulsation in the microburst evolution. <br></br> These results highlight the capability of LES to reproduce complex phenomena like microbursts, indicating the potential usage of LES models to represent atmospheric phenomena of time and space scales between the convective scale and the microscale. These include short-lived convectively-generated damaging winds.

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