Spatiotemporal Characteristics of Drought Occurrences over Japan

Abstract

The drought climate of Japan from 1902 to 2009 was analyzed using an effective drought index (EDI). Drought regions were identified by hierarchical cluster analysis using drought characteristics (duration, severity, and onset and end dates) obtained from 50 observation stations. The results indicated that droughts could be divided into four groups (G1-G4) that reflected the local climate. The four groups were related to precipitation as follows. The summer rainy season affected groups G2-G4, in which droughts occurred mainly during spring and summer and were relieved before and after the rainy season. The G1 group was not affected by the summer rainy season and droughts were spread evenly throughout the year; it even had cases of droughts relieved by winter snow. All groups included dry conditions over the 108-yr period, and the driest conditions occurred in the late twentieth century. The statistical analysis of drought data showed that a total of 23 country-wide droughts occurred and that the most extreme droughts occurred in 1939-41 and 1984-85, with an EDI of 21.55. In addition, four dry seasons (1939-45, 1997-98, 1994-97, and 2005-09) were found using regime shift analysis. Regional droughts occurred 54, 54, 49, and 59 times in groups G1-G4, respectively. On average, short-term droughts with a duration shorter than 6 months occurred 3.5 times per decade, whereas long-term droughts extending over 1 yr occurred 0.3 times per decade. The drought duration and intensity were used to calculate the statistical return period of country-wide droughts. The 1939-41 drought had the longest return period, at 104.7 yr. The 1987-88 and 1995-97 droughts had return periods of 65.9 and 65.5 yr, respectively.

Comparison of Projection in Meteorological and Hydrological Droughts in the Cheongmicheon Watershed for RCP4.5 and SSP2-4.5

“…Many other studies have also reported drought occurrences in the country [36][37][38]. Similar findings have been reported from North Korea [56][57][58], Japan [58], and China [59,60] that neighbor South Korea. There are also studies from other parts of the globe that have reported increased occurrences of droughts using SPI, SPEI, and SDI [61][62][63].…”

Extreme drought in the recent two decades in northern China resulting from Eurasian warming

“…Two decadal periods around the 1970s' and after the 1990s' deserve attention. Kim et al (2011) consider that extreme droughts during the stages of 1967-1969 and 1994-1996 are mainly caused by consecutive shortages of summer rainfall, the extreme event occurred in northern China, Japan and the Korean Peninsula (Lee et al 2012). …”

A study on the predictability of the transition day from the dry to the rainy season over South Korea

“…The EDI is a daily index that represents a continuous period and daily strength changes as objective values; it is an intensive measure that considers water accumulation with the weighting function of time passage. The merits of the EDI have been verified by many studies (Morid et al 2006;Pandey et al 2008;Lee and Byun 2009;Kim et al 2011;Lee et al 2012). The EDI is calculated using three equations:…”