3:30 PM - 3:45 PM
[ACG31-01] Aircraft observation of typhoon environments using dropsondes of the Taiwan ASTRA jet
Keywords:typhoon, aircraft observation, dropsonde observation, atmospheric river
The T-PARCII (Tropical cyclone-Pacific Asian Research Campaign for Improvement of Intensity estimations/forecasts) project has been performing in situ aircraft observations of typhoons since 2017. We observed supertyphoon Lan on 21-22 October 2017 and supertyphoon Trami on 25-28 September 2018 using the Japanese jet aircraft in collaboration with the Taiwan DOTSTAR team. The observed dropsonde data were transmitted to GTS (Global Telecommunication System) in real time and were used for typhoon forecasts in 2018. However, the dropsonde system of the Japanese aircraft has no longer been available since the jet aircraft was replaced by new one. Consequently, T-PARCII asked the Taiwan DOTSTAR team to help for typhoon observations and Taiwan kindly provided us the ASTRA jet equipping dropsonde facility.
A test flight of ASTRA was performed over the Taiwan-Okinawa region on 8 November 2019 and highly humid region adjoining a dry region was observed by the ASTRA dropsonde system. A moist layer to the southeast of the Okianwa main island and a dry region to the north of Ishigaki were observed. The dropsonde observations were made to the south and north of Ishigaki and the observed data were compared with the JMA balloon sonde observation at Ishigaki at 00 UTC 8 November.
The first flight of the ASTRA observation was made for 03-09 UTC 31 August 2020 to observe Typhoon Maysak (2020). The purpose of the flight was to observe the environment of the typhoon. Maysak developed to the east of the Philippines on 29 August and moved northward with intensifying. The aircraft observation was made in the region to the south of the Okinawa main island when Maysak was intensifying. Seven dropsondes were launched around the typhoon and the observed data were transmitted to the JMA through GTS. Unfortunately, the observed data were limited in the upper layer because of a trouble of the Vaisala dropsonde receiving system. The limited data were used for data assimilation by the JMA.
The second flight was made for 03-08 UTC 8 October 2020 to observe the environment of Typhoon Chan-Hom (2020). The typhoon was generated to the east of Okinawa and moved northwestward. Although Chan-Hom was less intense typhoon with a lifetime-minimum central pressure of 965 hPa, it caused a severe landslide in Mie Prefecture and a heavy rainfall over Izu islands. Eleven dropsondes were launched in the surrounding region of the typhoon center and atmospheric data were obtained throughout the troposphere from 200 hPa to the surface. An important characteristic of Chan-Hom is an accompanied corridor of large water vapor on its east side named an atmospheric river. The easternmost point of dropsonde observation was almost the edge of the atmospheric river and a highly humid layer below 300 hPa was observed at 134.343°E and 27.454°N.
In addition, Taiwan DOTSTAR team observed a weak tropical cyclone which approached Taiwan with an expecting disaster on 5 November 2020. They also provided us the observed dropsonde data. These data have been used for studied of typhoons and data assimilation experiments. In 2020, a supertyphoon Haishen passed along the west coast of Kyushu and a huge disaster was expected. This was an important case to be observed. However, The ASTRA jet was not available for the typhoon observation and we had to give up an aircraft observation of the typhoon. This impressed strongly that Japan should have its own observation aircraft.
A test flight of ASTRA was performed over the Taiwan-Okinawa region on 8 November 2019 and highly humid region adjoining a dry region was observed by the ASTRA dropsonde system. A moist layer to the southeast of the Okianwa main island and a dry region to the north of Ishigaki were observed. The dropsonde observations were made to the south and north of Ishigaki and the observed data were compared with the JMA balloon sonde observation at Ishigaki at 00 UTC 8 November.
The first flight of the ASTRA observation was made for 03-09 UTC 31 August 2020 to observe Typhoon Maysak (2020). The purpose of the flight was to observe the environment of the typhoon. Maysak developed to the east of the Philippines on 29 August and moved northward with intensifying. The aircraft observation was made in the region to the south of the Okinawa main island when Maysak was intensifying. Seven dropsondes were launched around the typhoon and the observed data were transmitted to the JMA through GTS. Unfortunately, the observed data were limited in the upper layer because of a trouble of the Vaisala dropsonde receiving system. The limited data were used for data assimilation by the JMA.
The second flight was made for 03-08 UTC 8 October 2020 to observe the environment of Typhoon Chan-Hom (2020). The typhoon was generated to the east of Okinawa and moved northwestward. Although Chan-Hom was less intense typhoon with a lifetime-minimum central pressure of 965 hPa, it caused a severe landslide in Mie Prefecture and a heavy rainfall over Izu islands. Eleven dropsondes were launched in the surrounding region of the typhoon center and atmospheric data were obtained throughout the troposphere from 200 hPa to the surface. An important characteristic of Chan-Hom is an accompanied corridor of large water vapor on its east side named an atmospheric river. The easternmost point of dropsonde observation was almost the edge of the atmospheric river and a highly humid layer below 300 hPa was observed at 134.343°E and 27.454°N.
In addition, Taiwan DOTSTAR team observed a weak tropical cyclone which approached Taiwan with an expecting disaster on 5 November 2020. They also provided us the observed dropsonde data. These data have been used for studied of typhoons and data assimilation experiments. In 2020, a supertyphoon Haishen passed along the west coast of Kyushu and a huge disaster was expected. This was an important case to be observed. However, The ASTRA jet was not available for the typhoon observation and we had to give up an aircraft observation of the typhoon. This impressed strongly that Japan should have its own observation aircraft.