Western North Pacific Tropical Cyclone Formation and Structure Change Project Title and Principal Investigator(s) Background Scientific Objectives Field Experiment Requirements Tropical Cyclone Structure-2008 (TCS-08) ONR/NRL Funded Projects Monsoon depressions are the source of the large TCs in the western North Pacific (e.g., Harr et al. 1996 Mon. Wea. Rev.). Mesoscale convective systems within the monsoon depression determine the location and timing of TC formation One of the primary mechanisms for changing the outer wind structure of a mature TC is the formation of a secondary eyewall (R. Stenger, PhD dissertation, in progress) Western North Pacific Tropical Cyclone Formation and Structure Change Patrick A. Harr (paharr@nps.edu) Russell L. Elsberry (elsberry@nps.edu) Naval Postgraduate School Monterey, CA 93943 Collect observations of the Mesoscale Convective Vortices structure and evolution in regions of tropical cyclone (TC) formation Assess and advance the prediction of TC formation with COAMPS Observe the external and internal processes leading to TC outer wind structure changes relative to the structure that exists at the time of formation Observe and compare with COAMPS-predicted latent heating profiles during TC formation. Sample the monsoon depression dynamic and thermodynamic structure leading up to formation time. Obtain three-dimensional observations by the NRL P-3 ELDORA and Doppler wind lidar of the Mesoscale Convective System that forms near the center of a monsoon depression as merger with the depression circulation occurs Monitor TC structure to document only small changes until secondary eyewall occurs, and then have NRL P-3 observations to document the role of an inward-spiraling outer rainband to complete the secondary eyewall