New typhoon observation device that does not require a parachute demonstrates high accuracy in field tests

Japanese researchers have demonstrated the high accuracy of a newly developed typhoon observation device designed to be dropped from an aircraft into the eye of a typhoon. The results are published in the journal Scientific Online Letters on the Atmosphere (SOLA).

Dropsondes are small, disposable devices dropped from aircraft that measure and transmit atmospheric data such as temperature, humidity, and wind speed as they fall. The new dropsonde iMDS-17 weighs only 130 grams and is made primarily of biodegradable materials. Due to its fins and lightweight body, the iMDS-17 can descend without a parachute, unlike traditional dropsondes.

To predict whether a typhoon will develop and where it will move, it is important to know how temperature, wind, and humidity are changing. In Japan, airborne equipment called radiosondes are commonly used to observe the upper atmosphere. Radiosondes are launched from land using rubber balloons. However, the strong winds and rain that accompany typhoons that form and develop over the ocean make this process difficult.

To overcome this shortcoming, a research group at Nagoya University, in collaboration with Meisei Electric, developed Japan’s first dropsonde that can be dropped from an airplane into the eye of a typhoon to obtain vertical profiles of temperature, humidity, and wind.

Project Associate Professor Yukie Kaneda of Nagoya University and colleagues conducted a study to evaluate the performance of a newly developed dropsonde in collaboration with researchers from Meisei Electric and Disaster Prevention Science and Technology Research Institute.

They evaluated performance by comparing data from their own dropsonde with data from a radiosonde with guaranteed accuracy used by the Japan Meteorological Agency.

Previously, dropsondes were rarely evaluated because their use was limited to oceans and simultaneous comparisons with radiosondes were impractical.

In the study, which took place on March 27 and 28 on one of the islands of Okinawa, Japan, a dropsonde and a reference radiosonde were launched simultaneously in the same balloon. A cutter with a timer was placed between the balloon and the two instruments.

When the balloon reached an altitude of 12 km, a timer was activated and both instruments separated from the balloon and fell. Each instrument measured temperature, wind, and humidity during the descent, and data from the dropsonde was compared with data from the radiosonde.

The difference between the dropsonde and radiosonde data was less than 1 K and 2 m/s. Temperature and wind are measured at altitudes ranging from 9 km to 2 km, respectively. The results showed the dropsonde’s high performance in temperature and wind observations. However, the humidity tended to be drier than that measured by radiosondes, and still needed improvement.

In order to observe dropsondes under actual storm conditions, on October 9th and 10th, 2024, Project Associate Professor Kaneda and Professor Kazuhisa Tsuboki of the Institute for Space-Earth Environmental Research, Nagoya University, flew a total of 500 meters into the typhoon’s eye from an aircraft. dropped a number of dropsondes. Balijat.

Mr. Kaneda said, “On October 9, we had just arrived near the center of the storm area during the typhoon formation stage.The atmospheric profile of the observed mid-latitude typhoon was determined by the WMO’s Global Telecommunications System (GTS). It was distributed all over the world and used for observation.” weather forecast system.

“This time, we pre-verified the humidity data from the dropsonde and the data has been improved. We plan to conduct another aerial observation using this dropsonde in 2025.”