Journal of Natural Disaster Science

AN AUTOMATIC STORM TRACKING METHOD USED TO ANALYZE TRAVELLING CHARACTERISTICS OF HEAVY RAIN AREAS

Kuniyoshi TAKEUCHI
Professor, Department of Environmental Engineering, Yamanashi University

(Received 30 Nov., 1984 and in revised form 7 May, 1985)

Abstract

A large amount of digital information has been recorded at the various rain gauging radar stations operated by the Ministry of Construction of the Government of Japan. A computer-aided automatic storm tracking method is indispensable for analyzing this bulky MT data. The method reported in this paper automatically traces the centroid of the heavy rain area over a given truncation level.

As the truncation level, 16 mm/h was selected, the unit heavy rain area being 2.04 km x 3.4 km and the observation area subject to quantitative analyses having a 102 km radius. The heavy rain areas traced translate to nearly the same directions in the entire 102 km radius area and throughout the duration of a heavy rainstorm, except for typhoons in which the translation directions change as the eye of the typhoon moves. The translation direction is 0 degree to 10 degree to the right of the upper layer wind at 700 mb. The lifetimes of heavy rain areas were found to be less than around 20 minutes.

From those findings, I concluded that the movement of heavy rain areas can be forecasted by a simple extrapolation method with possible aid from upper layer wind observations, but that the forecast is limited to about 20 minutes unless meteorological dynamics also are considered.

Key words

radar, storm tracking, heavy rain