Winter weather in Japan Controlled by Large-Scale Atmospheric and Small-Scale Oceanic Phenomena

Yuta Ando1,2, Masayo Ogi3, Yoshihiro Tachibana1,3, Kunihiko Kodera1,4 and Koji Yamazaki5,6, (1)Mie University, Weather and Climate Dynamics Division, Tsu, Japan, (2)NIPR National Institute of Polar Research, Arctic Environment Research Center, Tachikawa, Japan, (3)University of Manitoba, Centre for Earth Observation Science, Winnipeg, MB, Canada, (4)Meteorological Research Institute, Ibaraki, Japan, (5)Hokkaido University, Sapporo, Japan, (6)NIPR National Institute of Polar Research, Tokyo, Japan
Abstract:
The important components of atmospheric circulation in the winter over the Northern Hemisphere are the Arctic Oscillation (AO) and Western Pacific (WP) pattern. Although in general positive (negative) AO and WP phases cause Siberia, East Asia, and Japan to be abnormally warm (cold). The low (high) temperature of the Sea of Japan, which cooling (heating) by these cool (warm) waters, despite the small size of the Sea of Japan, overwhelmed the warming (cooling) effect of the positive (negative) AO and WP. Linear regression analyses show that Japan tends to be warm (cool) in years when the Sea of Japan is warm (cool). Consequently, the temperature over Japan is controlled by interannual variations of small-scale oceanic phenomena as well as by large-scale atmospheric patterns (Ando et al. 2015).

However, we cannot obtain the conclusion that surrounding ocean temperature generally influence on the temperature because Ando et al. (2015) is case study of the winter of 2012. To obtain the general conclusion, we should use statistical analysis, i.e., correlation between the temperature and surrounding ocean temperature. However, large-scale atmospheric circulations affect both the temperature and the surrounding ocean temperature. This is the usual result that the temperature is significantly positively correlated with the surrounding ocean temperature. Thus, to know the “real” influence of the surrounding ocean temperature on the temperature, we must remove the influence of large-scale atmospheric circulation from the temperature variation. We considered the “new” method of removing influence of large-scale atmospheric circulations. In this study, we examined whether the surrounding ocean temperature generally influence on the temperature over Japan in winter using new statistically analysis method.

The surrounding ocean temperature is also significantly positively correlated with the temperature over Japan. This result is consistent with the finding of Ando et al. (2015). Consequently, the temperature over Japan is controlled by the surrounding ocean as well as by large-scale atmospheric patterns, statistically.

Reference

Ando, Y., M. Ogi, and Y. Tachibana, 2015: Abnormal winter weather in Japan during 2012 controlled by large-scale atmospheric and small-scale oceanic phenomena, Mon. Wea. Rev., 143, 54-63.

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