Researchers have successfully validated the impressive precision of a new device designed for observing typhoons. This instrument, known as a dropsonde, is intended to be released from an aircraft directly into the heart of a typhoon. It collects data on the storm’s atmospheric conditions while descending to the ocean. The innovative dropsonde is lightweight and primarily constructed from biodegradable materials, allowing it to fall without the use of a parachute, which sets it apart from traditional dropsondes.
Scientists in Japan have highlighted the high precision of their newly created device for observing typhoons. This device is specifically engineered to be released from an aircraft into a typhoon’s eye. The findings were published in the journal Scientific Online Letters on the Atmosphere (SOLA).
The dropsonde, a small, single-use gadget, is deployed from an aircraft to gather and relay atmospheric information such as temperature, humidity, and wind speed as it descends. The newly designed iMDS-17 dropsonde weighs just 130 grams and is made predominantly from biodegradable materials. Thanks to its fins and lightweight structure, the iMDS-17 can descend without utilizing a parachute, unlike standard dropsondes.
Understanding changes in temperature, wind, and humidity is crucial for predicting whether a typhoon will strengthen and its projected path. In Japan, radiosondes—airborne instruments—are typically used to assess the upper atmosphere. These devices are launched from the ground using a rubber balloon. However, the intense winds and rains linked to typhoons, which originate and develop over the ocean, complicate this process.
To address this limitation, a team from Nagoya University, in partnership with Meisei Electric Co., has created Japan’s first dropsonde capable of being released from an airplane into the eye of a typhoon, enabling measurement of vertical profiles of temperature, humidity, and winds.
Designated Associate Professor Sachie Kanada and her research team at Nagoya University, along with collaborators from Meisei Electric and the National Research Institute for Earth Science and Disaster Resilience, carried out a performance evaluation of their newly crafted dropsonde. They assessed its performance by comparing the data from the dropsonde with that from a highly accurate radiosonde used by the Japan Meteorological Agency.
Previously, dropsondes weren’t frequently analyzed because they were limited to ocean use, making it challenging to compare them simultaneously with radiosondes.
In their research, conducted on an Okinawan island in Japan on March 27 and 28, both the dropsonde and a reference radiosonde were launched at the same time using the same balloon. A timing cutter was installed between the balloon and the two devices. When the balloon ascended to 12 km, the timer was set off, and both instruments were released. As each descended, they recorded temperature, wind, and humidity, which were later compared.
The discrepancies between the data from the dropsonde and the radiosonde were minimal, with temperature differing by less than 1 K and wind speed by less than 2 m/sec at most altitudes ranging from 9 km to 2 km. These results indicated that the dropsonde performs highly for temperature and wind measurements. However, the humidity readings were generally lower than those from the radiosonde, indicating room for improvement.
To test the dropsonde in real storm conditions, on October 9 and 10, 2024, Designated Associate Professor Kanada, alongside Professor Kazuhisa Tsuboki from the Nagoya University Institute for Space and Earth Environmental Research, released a total of 50 dropsondes from an aircraft into the center of Typhoon Barijat.
Kanada shared, “Upon arriving at the storm center on October 9 during the early formation of the typhoon, we collected profiles of atmospheric conditions for the midlatitude typhoon, which were shared globally through the World Meteorological Organization’s Global Telecommunication System (GTS) for use in weather forecasting systems. This time, we verified the humidity data from the dropsondes, and it showed significant improvement. We aim to conduct another aircraft observation using this dropsonde in 2025.”
