[A-AS10] Stratosphere-troposphere (Atmospheric) Processes And their Role in Climate

[AAS10-P03] A study of the temperature-depleted layer at 30–36 km altitude observed by high-altitude radiosonde observations in Okinawa

*Takenari Kinoshita¹, Shin-Ya Ogino¹, Junko Suzuki¹, Ryuichi SHIROOKA¹, Qoosaku MOTEKI¹ (1.Japan Agency for Marine-Earth Science and Technology)

Keywords:Middle atmosphere , Atmospheric waves

The stratosphere, especially above 30 km altitude, is a region with fewer in-situ observations compared to lower altitude regions. Consequently, progress in understanding interaction between wave activities and dynamical general circulation in the middle and upper stratosphere has been delayed. With the purpose to evaluate the interaction, we have been conducting high-altitude radiosonde observations using large rubber balloons to obtain in-situ observation data in the upper stratosphere. From September 2022 to January 2024, a total of 35 profiles of data were obtained through six intensive observations conducted in Okinawa. In this presentation, we will introduce an overview of high-altitude radiosonde observations in Okinawa and a remarkable temperature-depleted layer at 30–36 km altitude on 28th September, 2022.
This temperature-depleted layer was a unique phenomenon and has not been seen in the stratosphere during the six intensive observations. On the other hand, this was also confirmed by satellite temperature data observed near Okinawa Island and ERA5 reanalysis data. In the temperature-depleted layer region, the hodograph analysis using radiosonde observation data showed an elliptical structure and a large low-temperature region with a horizontal scale of about 10000 km can be seen in the ERA5 reanalysis data. Then, using the ERA5 reanalysis and radiosonde observation data, we found that the low-temperature structure is caused by a baroclinic wave and upward propagating inertia gravity wave.