As Typhoon Lan approached Honshu on Saturday, October 21, Japanese researchers made their first flight into the eye of a tropical cyclone. American Hurricane Hunter aircraft have been flying data-gathering missions into Atlantic hurricanes and Pacific typhoons since July 1943, but discontinued flights into western Pacific typhoons in 1987.
Japan’s location in the Pacific Northwest Basin combined with its unique topography puts it at risk from typhoon-related damage. The Northwest Pacific Basin produces more tropical storms each year than anywhere else in the world. Every year since 1951, an average of four have made landfall on one of Japan’s four major islands, and an average of five typhoons have come within 500 km of the coastline.
Historical data for Japanese typhoons, however, includes significant uncertainty and intensity data for the most intense typhoons that have occurred since U.S. aircraft reconnaissance ended 30 years ago have a greater degree of error. To improve typhoon intensity and track forecasts, and to develop Japanese expertise in the observation of typhoons using aircraft, a research group based at Nagoya University established the Tropical cyclones-Pacific Asian Research Campaign for Improvement of Intensity estimations/forecasts (T-PARCII). The main thrust of the project involves flying data-gathering missions into typhoons much as American hurricane hunters do. A first test mission was flown in March of this year—and flights will continue into 2020—focused on the area to the south of Okinawa, where typhoons often reach maximum intensity and change direction.
Saturday’s flight into Typhoon Lan was the project’s first data-gathering mission. A Grumman Gulfstream II (G-II) twin engine business jet left Kagoshima Airport on the southern island of Kyushu at noon on October 21. It flew into Lan, which was developing rapidly at the time, at about 43,000 feet. Approaching the storm system from the west, the plane was able to penetrate the eye, where passengers saw blue skies, a wall of cloud, and the surface of the sea when near the center of the eye. The team shot some video footage while they were within the eye. During the course of the mission, 21 dropsondes were launched to gather information about temperature, humidity, pressure, and wind; observations were conducted with typhoon experts from Nagoya University and the University of the Ryukyus in Okinawa Prefecture.
Flights are not the only way in which T-PARCII is gathering data. A ground-based balloon equipped with a microscope camera, X-band precipitation radar, Ka-band cloud radar, aerosol sondes, and a drone will be used to observe typhoon-associated clouds and precipitation. The dropsonde data are assimilated into the Cloud Resolving Storm Simulator (CReSS), a cloud-resolving model developed by Nagoya University. T-PARCII’s work in improving typhoon intensity estimation and forecasts will contribute to typhoon resilience in Japan.