Winter Orographic Precipitation and ENSO in Sapporo, Japan

The effect of global climate change on the distribution of snow water is a great concern. Thus, it is important to clarify the characteristics of winter precipitation variability, including mountain precipitation, together with climate indices. In this study, regional snowfall characteristics were investigated with the daily gridded precipitation over Sapporo City (located on the Japan Sea side of Hokkaido in northern Japan), which was quantified by the APHRODITE method and by adding local precipitation observation data. We found places of showing large interannual variability that is different from that of daily precipitation variability. Applying an EOF analysis to the daily grid precipitation, we defined four local precipitation types. The occurrence of each precipitation type and associated atmospheric circulation was analyzed, and the results revealed that (except for the Super El Nino winter of 1997/1998) more snow fell in the southwestern mountains and inland areas during El Nino winters, and more snow fell in the northeastern plains and along the sea during La Nina winters. Continued development and evaluation of the precise data that incorporate local precipitation network is needed.

Automated summary

This study investigates the precipitation characteristics in Sapporo City, northern Japan, and finds that there is interannual variability in precipitation that is different from daily variability. The study also shows that El Nino winters result in more snowfall in southwestern mountains and inland areas, while La Nina winters result in more snow in northeastern plains and along the sea.