83rd Annual

Thursday, 13 February 2003
Low level jet development and its relation to surface inhomogeneities: RAMS LES simulations
Adrian Marroquin, NOAA/FSL, Boulder, CO; and E. Tollerud and F. Caracena

Several years of research on the low level jet (LLJ) over the Central High Plains has provided understanding of its synoptic and mesoscale characteristics. Until recently, because of coarse resolution, numerical models and observations were not able to provide insight into the submesoscale features of the LLJ and its relation to surface conditions. The data from the IHOP (2002) field experiment provide an excellent opportunity to investigate the influences of surface inhomogeneities on the behavior and development of the LLJ. Recent large eddy simulations (LES's) at 50-m horizontal resolution with the numerical model RAMS (see http://blue.atmos.colostate.edu/imagegallery/) support the idea that surface inhomogeneities (or SI: terrain, soil moisture, vegetation, etc) can influence in significant ways the boundary layer circulations. At a coarse resolution, a simulation done with RAMS at 4 km grid spacing over the IHOP domain (nested within a 12-km grid), for the 1500 UTC 3 June 2002 case, shows a dynamic interaction of the LLJ and convective activity. Furthermore, in this work we investigate LLJ-SI interactions with RAMS LES's, initialized with lidar, radar, and dropsonde data collected during IHOP. These same data will also be used to further verify the model results.

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