A Study of Foehn in the Hokuriku District using the AMeDAS Data

Abstract

Meso-meteorological analysis on the Hokuriku foehn was carried out using AMeDAS data. Selecting the central Japan area as the analysis area, time series of the spatial distribution of wind, temperature and humidity fields are obtained. The surface winds blowing from the Pacific Ocean side to the Hokuriku district, take their course along the valleys which run from south to north in the central mountain ranges. There are three wind courses in the ranges, and strong foehn wind areas in the coastal plains along the Japan Sea side sector of these courses. Foehn wind varies diurnally, light by day and strong at night, which suggests the superposed effect of the southerly synoptic wind and the diurnally varying local wind. During foehn, there is sometimes a rainfall and sometimes none on the windward side. It is found that the Scorer parameter as well as moisture condition in the lower troposphere is responsible for the appearance of the windward rainfall. © 1982, Japan Meteorological Agency/Meteorological Research Institute. All rights reserved.