92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Monday, 23 January 2012: 5:00 PM
Typhoon Intensity and Structure Change Air/Sea Observational Strategies Employed During the TPARC/TCS08 and ITOP/TCS10 Experiments
Room 340 and 341 (New Orleans Convention Center )
Peter G. Black, SAIC/NRL, Monterey, CA; and J. D. Hawkins, S. Chen, E. R. Sanabia, P. A. Harr, and R. L. Elsberry

The strategy of combination, or ‘combo', deployment of AXBTs and dropsondes into pre-genesis, and mature tropical cyclones (TC's) within the Western North Pacific (WPAC) basin was utilized during the TPARC-Tropical Cyclone Structure (TPARC/TCS-08) and Interaction of Typhoons Over the Pacific (ITOP/TCS10) experiments over a two month period in 2008 and 2010. This sampling strategy enabled a unique view of the three- dimensional (3-D) oceanic thermal and atmospheric environments in evolving tropical systems to be obtained. Coupled with the low-level ocean drifting buoy/float deployment capability of the AFRC WC-130J aircraft, its long-endurance in excess of 12-hours and high-altitude capabilities (300 mb) demonstrates a new era in TC operational ocean feature observation capabilities for initialization and validation of new coupled air-sea TC models such as the NRL coupled COAMPS-TC model, brought on line for the first time during ITOP/TCS10.

Preliminary analysis of the TPARC and ITOP WC-130J AXBT data indicated that three of four systems that developed into typhoons in 2008 and two of three systems in 2010 developed within the WPAC oceanic region referred to as the ‘Southern Eddy Zone' between 16-24 N. In TPARC/TCS08, AXBT data for one case (Jangmi) showed Rapid Intensification (RI) over a warm eddy and subsequent Rapid Decay (RD) over a cold eddy while during ITOP/TCS10, another case (Fanapi) showed rapid development over a warm eddy. While underlying ocean conditions seemed not to be a factor in TC formation, or lack thereof, subsequent development did appear to depend on subsurface ocean eddy conditions, a result that makes monitoring these ocean conditions for coupled model use an important new consideration in TC observational requirements. Preliminary results from an AXBT ‘demo' program inaugurated during the 2011 Atlantic hurricane season has shown initial positive impact on the coupled COAMPS-TC model.

We suggest that this sampling strategy may prove effective in meeting emerging observational requirements for model initialization and validation as the use of coupled TC prediction models grow. This strategy of flying high in weak systems rather than flying low looking for closed circulations takes advantage of the high altitude and long range capability of the WC-130J aircraft and provides the ability to simultaneously map vertical atmospheric structure searching for signatures of mid-level as well as low-level spin-up at the earliest possible time while also mapping the surface wind field through use of the new Stepped Frequency Microwave Radiometer (SFMR), also flown on the WC-130J aircraft.

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