A New "Dropsonde" Sensor System Needs No Parachute to Brave a Typhoon
Designed to be dropped from a passing aircraft, these sensor packages could provide early warning for dangerous conditions.
Scientists from Nagoya University's Institute for Space-Earth Environmental Research, the National Research Institute for Earth Science and Disaster Resilience, the Disaster Prevention Research Institute at Kyoto University, and Meisei Electric Co. have developed a robust "dropsonde" sensor that can track typhoons — by being flung into them, without a parachute.
"A novel dropsonde, the iMDS-17, has been developed since 2017," the team writes by way of introduction to their work. "Owing to their light weight of approximately 130g, parachutes are not necessary when observing upper-air atmospheric conditions throughout the troposphere. Approximately the same technology as that of the Japan Meteorological Agency (JMA) operational radiosonde (iMS-100) was used, except that the pressure was measured directly using a pressure sensor."
The "dropsonde" sensor is based on the same principle as a radiosonde, a telemetry instrument designed to be hoist by a weather balloon — except, as the name implies, the dropsonde is simply… dropped. By design, it should be dropped from an aircraft flying at around 43,000 feet and a ground speed of 450 miles per hour — but, eager to expand its potential usage, the team's latest experiments have seen it adapted to being fired from a balloon-borne "dropsonde shooter" launch system.
The idea behind the sensor package is simple: monitoring the atmospheric conditions of typhoons, in order to figure out if it's likely to intensify and in what direction it's likely to travel — providing life-saving early warning of a potential landfall. To prove the concept, the team used the launch system to fire both a proven radiosonde and the new dropsonde; temperature, pressure, and humidity readings from both showed high accuracy from the new sensor system — though with improvements still to be made in the humidity readings.
As a further proof-of-concept, the team used a more traditional aircraft-drop approach to release a total of 50 dropsondes into a real-world typhoon: Typhoon Barijat. "On October 9 [2024], we had just arrived around the storm center in the typhoon genesis phase," explains co-author Kazuhisha Tsuboki. "The observed profiles of atmospheric conditions for the mid-latitude typhoon were delivered worldwide via the Global Telecommunication System (GTS) of the WMO [World Meteorological Organization] and used for the weather forecasting systems. This time, we pre-verified humidity data of the dropsondes and the data was improved. Using this dropsonde, we are planning to have another aircraft observation in 2025."
The team's paper has been published in the journal SOLA under open-access terms.