Climatic change and interannual fluctuations in the long-term record of monthly precipitation for Seoul

Abstract

We examine the characteristic climatic changes recorded in the long-term precipitation data for Seoul, Korea. Since precipitation data for Seoul has been accumulated for over 230 years, it is very useful in studying climatic changes in the monsoon region. The statistical test used to detect the change point was performed for the annual precipitation from April to November. It was found that statistically significant change points occurred in 1881 and 1952. On the basis of the results of the change point test, we examined the characteristic of the precipitation for the periods 1771–1881, 1882–1952, and 1953–2000. In change point detection test for monthly precipitation, it was found that there was no significant change point for the months June, July, and October. By means of comparing the statistics between different epochs, the modern precipitation climates during 1882–1952 and 1953–2000 are found to be more normal than the premodern ones. The ‘July–August or July, July/August interactive and September modes’ were classified through the empirical orthogonal function (EOF) structures and were identified as the principal modes in every epoch, whereas the ‘July mode’ was the most prevalent mode in every epoch. We present discussions on the synoptic meteorology that is probably responsible for these occurrences. The ‘September mode’ has significantly diminished and the ‘August mode’ has predominated during the modern era. It may be noteworthy to observe that the rainy season has been concentrated into a short time period. The quasi-biennial and interannual variability including ENSO groups of periods have been quite strong, but the outstanding periods in the long-period group were weak. Copyright © 2005 Royal Meteorological Society