Precipitation trends over the Korean peninsula: typhoon-induced changes and a typologyfor characterizing climate-related risk

Abstract

Typhoons originating in the west Pacific are major contributors to climate-related risk overthe Korean peninsula. The current perspective regarding improved characterization ofclimatic risk and the projected increases in the intensity, frequency, duration, and powerdissipation of typhoons during the 21st century in the western North Pacific regionmotivated a reappraisal of historical trends in precipitation. In this study, trends in themagnitude and frequency of seasonal precipitation in the five major river basins in Koreaare analyzed on the basis of a separation analysis, with recognition of moisture sources(typhoon and non-typhoon). Over the 1966–2007 period, typhoons accounted for 21–26%of seasonal precipitation, with the largest values in the Nakdong River Basin.Typhoon-related precipitation events have increased significantly over portions of Han,Nakdong, and Geum River Basins. Alongside broad patterns toward increases in themagnitude and frequency of precipitation, distinct patterns of trends in the upper andlower quartiles (corresponding to changes in extreme events) are evident. A trendtypology—spatially resolved characterization of the combination of shifts in theupper and lower tails of the precipitation distribution—shows that a number ofsub-basins have undergone significant changes in one or both of the tails of theprecipitation distribution. This broader characterization of trends illuminates therelative role of causal climatic factors and an identification of ‘hot spots’ likely toexperience high exposure to typhoon-related climatic extremes in the future.