P28  Simulation of Snow Cover Changes over Central Japan in the Late 20th Century

Hiroaki Kawase, Masayuki Hara, Takao Yoshikane, Noriko Ishizaki, and Fujio Kimura, Japan Agency for Marine-Earth Science and Technology, Japan

We focus on the dramatic decrease in the snow cover on the Japan Sea side of Central Japan in the late 20th Century. The WRF-ARW model accurately simulated the interannual variation of maximum snow depth (SNDmax) and the dramatic decrease in SNDmax between the 1980s and the 1990s. We then conducted a Pseudo Climate Simulation (PCS) in the 1990s, which assumes the mean atmospheric fields in the 1990s and the perturbation from the mean atmospheric fields in the 1980s. The PCS method is expected to evaluate the impacts of changes in the mean atmospheric fields on the snow cover changes. The PCS simulates the decreases in SNDmax over the coastal area, which are comparable to the changes in SNDmax simulated by the hindcast experiment. On the other hand, the PCS simulates the slight decreases in SNDmax over the mountainous area, where the slight increases in SNDmax are simulated by the CTL. Therefore, the changes in the mean atmospheric fields are main factors of the snow cover decrease over the coastal area, while both changes in the mean atmospheric fields and the perturbation contribute to the snow cover changes over the mountainous area.