Modeling of the Atmospheric Circulation in the Santa Barbara Channel
Award #: N00014-98-0113 LONG-TERM GOALS The long term goal is to better understand and predict the physics of small to mesoscale circulations in the coastal atmosphere using a combination of observations and model simulations. OBJECTIVES The objective of this project is to determine how local, coastal wind fields in the Santa Barbara Channel (SBC) region are affected by slowly varying synoptic weather conditions and diurnal heating. Hindcast simulations have been performed for a two-week period
... r a two-week period in April that encompassed both strong synoptic forcing representative of winter conditions, and circulations that are driven by local heating, which are more typical in summer. Wind stress from these simulations will be provided to investigators examining the role of local winds in forcing coastal ocean circulations. APPROACH Simulations were performed using the Advanced Regional Prediction System (ARPS) mesoscale model developed at the University of Oklahoma (Xue et al. 1995) . ARPS is a nonhydrostatic atmospheric mesoscale model that uses a terrain following coordinate system with both parameterized and explicit cloud physics. Two levels of nesting were employed in the simulations using a horizontal grid size of 60 x 60 and grid spacing of 12 km and 4 km, respectively. A stretched 32 level vertical grid was applied with grid spacing starting at 20 m for the finest resolution at the surface expanding to 450 m for the top grid levels. Initialization and boundary forcing for the model were prescribed using the National Center for Environmental Prediction (NCEP) 40 km Eta model analysis, which is available in 3 hour increments and archived at the National Center for Atmospheric Research. Hindcasts were performed over 12-hr periods with a 3 hour spin up prior to the beginning of the hindcast. WORK COMPLETED Hindcasts from April 7-14th, 1998 are nearing completion and will be interpolated to a uniform latitude/ longitude grid for distribution to ocean modeling efforts. We have started to examine the role of terrain and local heating in determining the strength and location of wind stress shear over the SBC.