Relation between Spatial Representation Data and Number of Years Data Examined

Long-term Annual Precipitation Records from Stations near Nagoya, Japan

Abstract

 To investigate regional long-term trends in annual precipitation from a limited number of observation stations, it is useful to understand the relation between the spatial representation of data and the number of years of long-term data examined. As a case study, we used 79 years of precipitation data from five stations near Nagoya, Japan, to analyze the relation between the spatial representation and number of years of data. When the years of data were fewer than 45, the trend differed for all five stations. However, when more than 70 years of data were used, the trend was the same for all five stations. When the years of data were more than 45 but fewer than 70, four of the five stations exhibited the same trend. Results show that at least 70 years of data are necessary to determine the long-term trend of precipitation in our study area, which is a large watershed affected by both Pacific climate and Sea of Japan climate.