Seasonal Changes of Daily Frequency of Squalls in the NW-PACIFIC

Abstract

This paper was prepared to give the general aspect of the annual changes of daily frequency of squalls in the NW-PACIFIC. The materials used here are marine data reports from the Japanese fleets and civil ships collected and compiled by the Japanese Navy, based on the same materials a contribution “ On the Visibility in the NW-PACIFIC ” has already been written by ARAKAAITA (1950)
To obtain the monthly means of daily frequency of squalls, statistics were made in the following way: the NW-PACIFIC has been divided into squares,2.5 degree longitude in width, and 2.5 degree latitude in length. Referring to the files compiled, the time intervals (in hours) required by ships to traverse each 2.5 degree square were summed up. Then, the number of squalls encountered in each of the time intervals 1^h-4^h, 5^h-8^h, 9^h-12^h, 13^h-16^h,17^h-20^h and 21^h-24^h was calculated. The result thus obtained is tabulated as follows: