A joint research between the Kyoto University Disaster Prevention Research Institute and the Research Center for Advanced Science and Technology, the University of Tokyo, revealed that the bomb depression has increased rapidly over the northwestern Pacific since the latter half of the 1980s.

 In order to investigate the long-term changes in the so-called explosive cyclogenesis, which develops rapidly and causes disasters due to blizzards, waves, and storm surges, this study used global atmospheric reanalysis data instead of satellite observations.Analysis of homogeneous data using only ground and high-rise observations over the past 1970 years from 1958 to 2012, before the end of the 55s when satellite observations began, revealed a rapid increase in the cyclone in the northwestern Pacific Ocean. I found it.

 In particular, the rapid increase in January was remarkable, so when examining the environmental field in January, after the latter half of the 1s, the cold air blowout weakened due to the weakening of the winter monsoon from the Eurasian continent, and from southern China to the East China Sea and Southeast Asia. It was found that the lower troposphere was moistened at high temperature and the frontal zone where low pressure was likely to occur was strengthened.It is said that the mechanism of the explosive cyclogenesis surge is that the cyclone with moist air generated in this frontal zone rapidly develops in the northwestern Pacific while passing through the southern coast of Japan.On the other hand, before the latter half of the 1s, there were few low pressure systems that developed in this way.

 This study showed that not only the changes in the jet stream in the upper troposphere, which had been pointed out in the past, but also the changes in the cyclone development factors associated with the warming and moistening of the lower troposphere affect the generation of the cyclone.This suggests that climate changes such as subtropical warming and moistening also bring about changes in the development factors and the number of occurrences of explosive cyclogenesis, and it can be said that they provide important insights in future prediction of climate. ..

Paper information:[Journal of Climate] Rapid increase of explosive cyclone activity over the midwinter North Pacific in the late 1980s

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