Diurnal Variations of Summertime Precipitation in South Korea in 2009 Using Precipitation Reanalysis Data

Abstract

Diurnal variations of Korean summertime (June-August) precipitation in 2009 were investigated using hourly National Institute of Meteorological Research/Korea Meteorological Administration (NIMR/KMA) Forecast Research Laboratory (FRL) precipitation data that had high spatial (5 km by 5 km grid distance) and temporal (1 h) resolutions. Using the techniques of multiresolution analysis and Incomplete Gamma Function, NIMR/KMA FRL precipitation reanalysis data are produced from the observations of about 680 Automatic Weather Systems and reflectivity data from 10 radars over South Korea.
Three dominant modes of diurnal variations in 2009 summer precipitation over South Korea were indentified via the cyclostationary EOF (CSEOF) technique. Nocturnal precipitation maxima were the result of rain band enhancement from instability due to radiative cooling at the cloud top during the nighttime. This precipitation over the central region of South Korea strengthened and moved rapidly southeastward during the nighttime and then dissipated in the southern coast area of Korea by mid morning. Over the north-central region of South Korea, the daytime prevailing precipitation was nearly stationary from early morning to late afternoon. The precipitation over the southern coastal periphery of Korea also moved slowly eastward from midnight to mid afternoon.