Tropical Cyclone Structure-2008 (TCS-08)ONR/NRL Funded Projects Background Project Title and Principal Investigator Scientific Objectives Field Experiment Requirements • Extratropical transitions (ET) of Tropical Cyclones (TCs) are often accompanied by hemispheric drops in forecast skill (e.g., Jones et al. 2003 Wea. and For.). • Observations in sensitive regions have bigger impact during ET than during other periods (Cardinali et al. 2007 QJRMS) • Stochastic convection has significant impact on ensemble behavior in tropics (Reynolds et al. 2008) and on ensemble TC tracks. Tyranny of Scales (NRL Base-funded project) Carolyn A. Reynolds (firstname.lastname@example.org) Naval Research Laboratory Monterey, CA 93943 • Use Singular Vector (SV) sensitivity and field observations to learn about important large-scale mechanisms impacting TC predictability during recurvature and ET. • Assess the ability of SVs to identify sensitive regions, in comparison with other targeting techniques. • Determine if observations in sensitive regions have larger impact on forecasts of TC recurvature and ET than observations in non-sensitive regions. • Determine if unresolved processes are having significant impact on predictability through ensemble experiments. • Sample sensitive regions during recurvature and extratropical transitions using the C130 and Falcon dropsonde measurements, off-time soundings, and additional satellite data. • Sample non-sensitive regions as well, so post-time data impact comparisons may be made. • Have as much data as possible on GTS for real-time and post-time assimilation.