Oral or Poster

IAMAS

M10 - Middle Atmosphere Symposium

On wave activities and temperature-depleted layer obtained from high-altitude radiosonde observations

It has been understood that atmospheric waves and their driving material circulation in the stratosphere directly influence precipitation activity and the jet stream in the troposphere. However, the stratosphere, especially above 30 km altitude, is a region where we have fewer in-situ observations than in the lower altitude regions. Therefore, it is found that large differences among reanalysis data above 30 km altitude and that the differences increase with height, resulting in many uncertainties. To obtain in-situ observation data in the middle and upper stratosphere and to evaluate wave activities and their driving material transport and background field, high-altitude radiosonde observation using large rubber balloons have been conducted. In this presentation, we introduce the status of the high-altitude radiosonde observations in Okinawa, Japan. During the observation period, in each of intensive observations in September 2022 and July 2024, a remarkable temperature-depleted layer around 35 km altitude was observed. Using the radiosonde and satellite observation data and reanalysis data, we found that the temperature-depleted layer in September 2022 is caused by the superposition of an upward propagating gravity wave and a westward propagating planetary-scale wave. On the other hand, it is found that the temperature-depleted layer in July 2024 is caused by an upward propagating gravity wave with a large vertical wavelength, which is likely generated around typhoon Gaemi.