Dynamics of the Coastal Jet near Cape Mendocino

Part I: Numerical Simulation Results

Dave Rahn, M.S. Candidate

University of Wyoming

Abstract:  In June 2004 several flights were conducted by the Wyoming King Air near Cape Mendocino , California in order to examine the fine-scale features of the coastal jet (CJ) that often forms during the summer.  The primary goal of these flights is to ultimately measure the actual pressure gradient by flying redundant legs on a particular isobaric surface while recording the height.  These horizontal legs are supplemented by several saw-tooth legs in order to obtain information on the vertical structure of the CJ.  Since the flights cover a limited area, a numerical simulation is run in order to augment the fine-scale data obtained by these flights.  The model results proved to be quite accurate, as verified by the in situ data.  In this first seminar of two, the results of the numerical simulation are presented.  These results are used to describe the synoptic and mesoscale features in the vicinity of Cape Mendocino .  This includes a strong pressure perturbation in the vicinity of the cape, as the northerly winds associated with the Pacific High interact with the coastal topography.  In the lee of the cape, several other processes act to enhance and modify the pressure gradient greatly.  This interaction is also influenced by the strong thermal contrast in the vicinity of the CJ.  The subsequent seminar concludes this discussion by presenting the results of the in situ data and putting it in context of the larger scale dynamics presented in this first part.