Variability and Singularity of Seoul, South Korea, Rainy Season (1778–2004)

Abstract

The 227-yr daily precipitation record gathered for Seoul, South Korea, represents one of the longest instrumental measurements, which provides an exceptional opportunity for detecting climate singularity (a property of phase locking to annual cycle) of extreme weather events and multidecadal–centennial variability of the rainy season structure. From late June to early September, the occurrence of heavy rain events shows a climatological quasi-biweekly oscillation. The rainy season characteristics, including the dates of onset, retreat, summit, and the duration, all show significant centennial variations. The rainy season summit shows a tendency toward delayed occurrence, which changed from the 37th pentad (P37; 30 June–4 July) during the 1778–1807 period to P44 (4–8 August) during the 1975–2004 period. The amplitude of the interannual (2–6 yr) variation of summer precipitation shows a prominent fluctuation with a 50-yr rhythm. A notable climatological break (around 9–13 August) divides the rainy season into a changma (Korean for continuous rain period) and a post-changma period. The major modes of subseasonal variability of the rainy season are characterized by an advanced changma and an enhanced post-changma, respectively. The former is dominated by biennial variation, whereas the latter has a major 5-yr spectral peak, suggesting that the processes leading to their variability are different. The occurrence of severe drought events exhibits a 4-yr spectral peak along with large power on a centennial time scale, while the severe flood events have a spectral peak at 3 and 19 yr, respectively. The remarkable climate variability in Seoul rainfall suggests that trends detected by using a 50-yr-or-shorter precipitation record likely reflect natural variability.

Variability in the East Asian Monsoon: a review

“…Many previous studies indicated that the EASM exhibits significant interdecadal variability (Zeng et al, 2007;Ding et al, 2008;Zhou and Huang, 2009). In particular, an increase in August rainfall and change in seasonal structure of Korean rainfall were reported Ha and Ha, 2006;Wang et al, 2007;Ha et al, 2009;Lee et al, 2010). Figure 3 shows the climatological annual cycle of Korean rainfall for the periods 1954periods -1975periods (hereafter referred to as PI) and 1976periods -2010 (hereafter referred to as PII) determined by KMAR data.…”

Long-Term Changes of Seasonal Progress in Baiu Rainfall Using 109 Years (1901-2009) Daily Station Data

“…This is of insufficient length in order to discuss whether these observed trends are forced by external influences such as anthropogenic activities because inter-decadal natural climate variability cannot be discounted in a 0-year-or-shorter record (Wang et al 2007). In addition, the trends indicated by the previous studies are not necessarily tested statistically enough.…”

Trends in autumn rain of West China from 1961 to 2014

“…They, however, mostly focused on changes in annual or summer precipitation and less attention has been paid to autumn precipitation. As is known, autumn precipitation occurring in West China is a typical climate phenomenon, which is named Bautumn rain of West China^and similar to Masika and Vuli in East Africa (Camberlin and Philippon 2002) and postChangma in Korea (Wang et al 2007). The autumn rain of West China usually occurs in September-October, and its rainfall amount is registered as the second peak of local precipitation.…”