Hong Kong is situated in a tropical cyclone prone region in Asia-Pacific. From May every year, tropical cyclones form over the Pacific Ocean and impact Hong Kong in different magnitude. In order to provide forecast and warnings of tropical cyclones, accurate meteorological measurements are needed to measure and predict the strength and direction the cyclone is moving. Essential information of the cyclones such as temperature, wind, air pressure and humidity throughout the cyclone are needed. But tropical cyclones are dangerous storms. It is difficult and hazardous to get inside them. One way to get this information safely is to use dropsondes.
Dropsonde is a weather device packed with instruments and sensors, attached by a little parachute. It is designed to be dropped out of an aircraft at high altitudes and fall slowly to the surface. During the descent, location and atmosphere around the atmosphere are sent back to the aircraft by radio transmission.
Dropsonde mission is a collaboration with the Hong Kong Observatory (HKO), which collects extra meteorological data on tropical cyclones to enhance the monitoring of tropical cyclones. The first dropsonde mission was flown in September 2016 when Typhoon Megi traversed the northern part of the South China Sea.
CL605 will be deployed to collect more meteorological data as requested by HKO when tropical cyclones enter the South China Sea and may affect Hong Kong. Roughly 10-15 dropsondes are released during a typical dropsonde flight within the Hong Kong Flight Information Region(FIR), with each flight lasting about 3 hours.