11B.8 A Dropwindsonde Analysis of the Thermodynamic and Dynamic Structure and Evolution of STY Megi (2010)

Thursday, 19 April 2012: 9:45 AM
Champions AB (Sawgrass Marriott)
Andrew B. Penny, NPS, Monterey, CA; and P. G. Black, R. Creasey, and P. A. Harr

During August-October 2010, the Impact of Typhoons on the Ocean in the Pacific (ITOP) field program was conducted over the Western North Pacific. Objectives of the field program were centered on measurement and analysis of the air-ocean interface and impacts on tropical cyclone intensity and structure. The primary observations were obtained via deployment of dropwindsondes and Airborne eXpendable BathyThermographs (AXBTs) from WC-130J aircraft operated by the USAF 53rd Weather Reconnaissance Squadron (Hurricane Hunters).

During ITOP, six aircraft missions were flown into Supertyphoon (STY) Megi to observe the atmospheric and oceanic structure from formation through a period of rapid intensification and eventual landfall over the Philippines. While at peak intensity (890 hPa minimum sea-level pressure) a unique set of flight plans were conducted to examine details of the air-ocean environment of the inner core. Dropwindsondes and AXBTs were launched just outside the radius of maximum winds during two consecutive flight legs flown tangent to the eyewall. The flight legs' nearly identical location relative to the storm's center allowed for an analysis into the evolution of Megi's inner-core structure over this ~1 hour time interval.

This paper will provide a thermodynamic and dynamic analysis of dropwindsonde observations collected during the evolution of STY Megi. Storm formation and early intensification are emphasized in this study. Recent theories on tropical cyclone formation and intensification are evaluated. In addition, the air-ocean interactions in the environment of the inner core of the supertyphoon are examined using the co-located dropwindsonde and AXBT data collected during the six aircraft missions into STY Megi.

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