INTERNATIONAL JOURNAL OF CLIMATOLOGY Int. J. Climatol. (2011) Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/joc.3392 Opposite trends in summer precipitation in South and North Korea Y. Kim, a B. Kang b and J. M. Adams c * a Korea Adaptation Center for Climate Change, Korea Environment Institute, Eunpyeong-gu, Seoul, Korea b Department of Civil and Environmental Engineering, Dankook University, Yongin-si, Gyeonggi-do, Korea c School of Biological Sciences, Seoul National University, Gwanak-gu, Seoul 151, Korea ABSTRACT: We analysed daily precipitation data at the rain gauge stations in North Korea over a period of 25 years from 1983 to 2007, and in South Korea over a period of 35 years from 1973 and 2007. We found a striking trend of decreasing summer precipitation across North Korea. By contrast, in South Korea, the trend is opposite: there is a major increase in summer precipitation. Also, the number of dry days in summer showed an increasing trend in North Korea and a decreasing trend in South Korea. For the number of days with heavy precipitation (i.e. days with above 50 mm/day daily precipitation) during summer, a decreasing trend was detected in North Korea, but no trend in South Korea. However, in South Korea, there was a significant increase of days with heavy precipitation over the whole year. These opposite trends in summer precipitation between North and South Korea were further confirmed using four global/regional satellite and rain gauge datasets of CPC Merged Analysis of Precipitation (CMAP), the Global Precipitation Climatology Project (GPCP), Precipitation REConstruction over the Land (PREC/L), and the Asian Precipitation-Highly Resolved Observation Data Integration Towards the Evaluation of Water Resources (APHRODITE). Copyright  2011 Royal Meteorological Society KEY WORDS precipitation; feedbacks; monsoon; climate trends; South Korea; North Korea Received 23 March 2011; Revised 18 June 2011; Accepted 28 September 2011 1. Introduction Long-term trends in precipitation have been observed in recent decades in many regions, and different trends from region to region have been reported. Increased precipitation has been observed in eastern parts of America, northern Europe, and northern and central Asia, and decreased precipitation has been recorded in the Sahel, the Mediterranean, southern Africa and parts of southern Asia. (IPCC, 2007). For the Korean Peninsula, a number of studies have examined historical precipitation patterns and trends (Ho, 2003; Chang and Kwon, 2007; Kim et al., 2009; Jung et al., 2010). Ho et al. (2003) have showed a sudden change in summer rainfall characteristics during the late 1970s in South Korea and suggested the observed sudden increase in the geopotential height at 700 hPa over mid-latitude Asia as a possible explanation for the increasing trend in precipitation. Chang and Kwon (2007) have investigated the spatial patterns of trends in the amount and intensity of total summer precipitation and the frequency of heavy precipitation for South Korea between 1973 and 2007, showing increasing trends in the amount of precipitation during summer months. Kim * Correspondence to: J. M. Adams, School of Biological Sciences, Seoul National University, Gwanak-gu, Seoul 151, Korea. E-mail: jonadams@snu.ac.kr et al. (2009) have applied Bayseian changepoint analysis to detect a change point in the 30-year (1976–2005) time series of the annual maximum precipitation averaged over South Korea. They found that a single change occurred around 1997 in the area-averaged annual maximum precipitation, which is consistent with an abrupt increase in the intensity and frequency of heavy precipitation after 1997. However, whilst these studies are consistent in finding the increasing trends in precipitation, they are limited to investigating precipitation in South Korea only. In this study, we investigated precipitation data ob- served at rain gauge stations in both South and North Korea to understand the spatial patterning of precipitation trends over the entire Korean Peninsula. We examined the precipitation amount, number of dry days and numbers of days with heavy precipitation, comparing trends in precipitation in South and North Korea. In addition, we analysed the global/regional gridded precipitation datasets to strengthen the validity of our findings with observations at stations. 2. Methods 2.1. Rain gauge data We examined daily precipitation data at 27 stations avail- able for North Korea from 1983 to 2007, and at 60 stations in South Korea from 1973 to 2007. For North Copyright  2011 Royal Meteorological Society