​The Government Flying Service (GFS) and the Hong Kong Observatory (HKO) today held a joint press conference on previous Tropical Cyclone Reconnaissance missions that were successfully completed with the use of its dropsonde system.

The GFS pointed out that during typhoons Saola and Koinu, it dispatched a Challenger 605 fixed-wing aircraft to deploy sondes at the designated co-ordinates and altitudes provided by the HKO to collect tropical cyclone meteorological data to enhance the monitoring of typhoons and preparedness.

During the press conference, HKO Senior Scientific Officer (Aviation Meteorological Data Analytics) Cheung Ping said the use of the dropsonde system enables first-hand meteorological data to be collected at various altitudes of the atmosphere, complementing the lack of conventional weather observations over the ocean, and facilitating the HKO in the analysis of the intensity and three-dimensional structure of tropical cyclones.

He further stated that the use of collected data in numerical weather prediction models could help improve the capability in predicting tropical cyclones.

GFS Pilot I (Aeroplane) Elaine Chan stressed that the dropsonde system is a safer and more effective way to collect meteorological data rather than sending an aircraft into a tropical cyclone.

The GFS and the HKO introduced the dropsonde system in 2016 to enhance the collection of meteorological data, with the first mission completed in September 2016.

The GFS Challenger 605 has since conducted 57 dropsonde missions to collect meteorological data for 38 tropical cyclones, including Typhoon Hato in 2017, Typhoon Mangkhut in 2018 and typhoons Saola and Koinu in recent months.

The dropsonde system, the GFS explained, deploys an aircraft to release the dropsonde unit from a high altitude. The unit, which contains meteorological sensors and a global positioning system, records wind direction, wind speed, temperature, air pressure and humidity at different locations during descent.

Moreover, the data is then transmitted back to the aircraft through radio transmission, then to the HKO in real time via the satellite system for analysis.