Using ASCAT Data to Determine Intensities of Developing Northwest Pacific Tropical Cyclones

Forecasters at the Joint Typhoon Warning Center (JTWC) provide tropical cyclone formation alerts (TCFA) and subsequent tracking for tropical cyclones (TCs) within the Unites States Pacific Command (USPACOM) area of responsibility, which includes the very busy Western North Pacific (NWPAC) basin. Due to the high volume of United States military personnel, assets, and allies in the NWPAC, this mission is very important. This research seeks to provide another tool for forecasters to use during the initial stages of TC development when it is difficult to use other techniques, such as Dvorak, to provide accurate and timely intensity estimates and center fixes. This study examines wind speed and direction data from the Advanced Scatterometer (ASCAT) instrument for storms in NWPAC from 2014-2016. Storm-centered images are sorted into intensity bins of 20, 25, 30, and 35 knots according to intensity data from the JTWC Best Track record for each storm. The analysis will focus on measuring the radius of closed wind speed contours and angle of wrap of open wind speed contours to empirically identify patterns in the shape and evolution of the wind field at different intensities during the early stages (from 20 to 35 knots) of TC development.