Characteristics of Spatial Distribution of Monthly Precipitation in the United States

Abstract

A basic analysis on the characrteristics of spatial distribution of monthly precipitation in the United States is resented. Monthly hydrologic quantities seem to be effective for detecting a relation between the long periodic variations of atmospheric conditions and meteorologic backgrounds in a large scale area. Data of precipitation at 176 ovservation stations in the United States for 5 years, from 1984 to 1988, was used. First, the deviation power and the spatial scales of precipitation area are defined statistically, and characteristics of the power and the scales are examined. In the next, the two-variate Gamma distribution function is applied to obataining a return period of a hydrological condition with large or small precipitation taking the spatial scale into account. At last, the relations between the spatial scales and distances between centers of high or low atmospheric pressure zones in each month in a year are also discussed.