Meteorological and Turbulence Data for the Japan/East Sea (JES) Experiment in Winter 2000 Researchers Djamal Khelif, dkhelif@uci.edu, 949 824-7437 Carl Friehe, cfriehe@uci.edu, 949 824-6159 University of California, Irvine Department of Mechanical & Aerospace Engineering Irvine, CA 92697-3975 USA Award Number N00014-99-1-0205 Objectives The objectives of this effort are to study the air-sea interaction under extreme conditions of cold-air outbreaks over the Japan/East Sea (JES) during winter. We are primarily interested in 1.) the determination of boundary-layer structure, 2.) the measurement of momentum, heat and water vapor (latent heat) air-sea fluxes and their spatial variability, 3.) parameterization of these fluxes, and 4.) model validation using observations. Approach A Navy CIRPAS Twin Otter research aircraft was outfitted with wind, temperature, humidity, IR sea temperature and aircraft motion and navigation sensors. High quality turbulence and meteorological measurements from thirteen aircraft flights over the JES in February 2000 were obtained. The bulk of the measurements were made inside the "Flux Center," an area off Vladivostok characterized by enhanced winds and surface fluxes due to the flow of cold and dry Siberian air channeled through the orographic gap near Vladivostok. Three basic research goals were addressed with different flight patterns: 1.) Flux mapping: after transit to the "Flux Center" south of Vladivostok, the surface-layer fluxes were mapped in a grid pattern at 100 feet with soundings to 5000 feet; 2.) Internal boundary-layer growth: after transit to the "Flux Center" a line of sounding from 100 to 3000-5000 feet was flown following an approximate streamline across the JES (five-minute flux legs were flown at 100 feet between soundings); and 3.) Flux divergence: after transit to the "Flux Center" a vertical stack pattern was flown to determine the flux divergence profile in the boundary layer. Results An internal boundary layer develops across the JES in cold-air outbreak conditions. The boundary-layer height, marked by a sharp inversion, initially drops and then increases. This is due to the initial topographical effect of the airflow out of the Vladivostok gap, where the boundary layer thins as the flow expands seaward under the strong inversion. This feature is predicted by the model of Scotti (2002) for the JES. Downstream of the gap, the boundary layer grows due to interaction with the sea as the square root of fetch. The high-quality turbulence and meteorological aircraft data are the first measurements to provide good spatial (both horizontal and vertical) coverage of the boundary layer over the JES in cold-air outbreak conditions. Their impact is to improve our understanding and parameterizations of air-sea fluxes and boundary-layer structure in extreme weather conditions. Their use as input and validation of JES mesoscale models such as COAMPS and MM5 will enhance the accuracy of these models.