Calculating Tropical Cyclone Critical Wind Radii and Storm Size Using NSCAT Winds
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
Pagination or Media Count:
Subjective and objective analyses of satellite scatterometer near-surface winds are utilized to estimate tropical cyclone TC critical wind radii and size over a region of the western North Pacific. An outer wind profile assuming a linear slope dependent on the TC latitude is used to determine the radial extent of cyclonic winds beyond a set radius. Inside the set radius, a partial conservation of angular momentum is assumed into the TC maximum wind radius and the 35, -50, and 100-kt radii are calculated. Nine TCs were investigated during the operating period of the NASA scatterometer NSCAT. Critical wind radii values in four quadrants front, right, rear, and left of the TCs are found to be comparable to the Joint Typhoon Warning Center JTWC critical wind radii values issued in warnings. The radial extent of cyclonic winds are also comparable to the radius of zero winds estimated by determining where the cyclonic flow turned to anticyclonic flow in the NSCAT sea-surface wind swaths.