Formation mechanism of Abend Thermik in the Mt.Asio Sky Sports Area

  • Yuko AKIMOTO, 2007: Formation mechanism of Abend Thermik in the Mt.Asio Sky Sports Area .

Abstract

Sky sports pilots utilize updraft when they fly. One of the famous updrafts is Abend Thermik that is a weak and wide updraft appearing in the mid afternoon. Mt. Asio located at the northeast of Tokyo is one of the most popular and famous sky-sports areas in Japan. Sky sports pilots report that Abend Termik sometimes appears in the area (We call this “Asio-abend” in the present study). However, the actual condition and formation mechanism of Asio-abend are not well known. The purpose of this study is to investigate the actual condition and formation mechanism of Asio-abend.

From the GPS records of the flight path of paragliders and hang gliders, we determine where updrafts exist. We also conducted numerical simulations of Asio-abend for typical events, using the WRF model. Simulated results roughly agreed with observed essential features of Asio-abend. Furthermore, we found that very weak up-valley winds appear over the west and east sides of the mountain before the sea breezes arrive at the mountain slope. After that, weak and wide updraft appears over the mountain slope where the sea breezes are coming. At that time, the air flow over the mountain occurs. Additionally, the height of the updraft associated with the incoming flow agrees with the observed one. From these, we conclude that the air flow over the mountain in the mid afternoon is the main factor of the formation mechanism of Asio-abend.

Abstracts of graduation thesis PDF(Japanese)