• Journal of the Korean earth science society
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• v.32 no.7
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• pp.761-769
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• 2011

Daily minimum temperature and freezing data of the Seoul weather station ($37^{\circ}$34'N, $126^{\circ}$57'E, Songwol-dong Jongno-gu Seoul, hereinafter Songwol) and freezing data of the Han River station ($37^{\circ}$30'N, $126^{\circ}$57'E, hereinafter Han River) were used to study the long-term variation of the freezing climate for Seoul, Korea, for the period of 100 years from 1907 to 2006. 'Freezing' of Songwol is defined that the water in outdoor fields is frozen, and 'freezing' of the Han River located 6 km away from Songwol is defined as the region 100 meters upstream of the second and fourth piers in the south end of the Han River Bridge is fully frozen. The mean first freezing date for Songwol was October 28, and one for Han River was December 28; these showed a late tendency, with the rate of 0.78 days $decade^{-1}$ and 3.47 days $decade^{-1}$, respectively. The mean annual freezing days was 159.06 days for Songwol and 50.33 days for Han River; each showed a $decade^{-1}$shorter tendency, with rates of 2.01 days $decade^{-1}$ and 5.24 days $decade^{-1}$, respectively. All the seven no-freezing years (1960, 1971, 1972, 1978, 1988, 1991, and 2006) for Han River came after 1950. The mean daily minimum temperatures of the first freezing dates for Songwol and Han River were $0.55^{\circ}C$ and $-12.22^{\circ}C$. The first freezing occurred after 6.43 days for Songwol and after 8.94 days for Han River with daily minimum temperature below $0^{\circ}C$. The annual minimum temperatures of Songwol and Han River exhibited positive correlations with the first freezing date and negative correlations with freezing days. The result shows that the freezing climate change is relevant to temperature change and is a part of overall climate change. By conducting additional studies with various methods and wider region, we will be able to monitor the freezing climate.