Lee, H.S., 2013. Abnormal storm waves in the East Sea (Japan Sea) in April 2012

The winter East Sea, a semi-enclosed sea surrounded by Korea in the west, Japan in the east and south and Russia in the north, normally experiences rough sea conditions due to East Asian monsoon and winter storms. In April 2012, record-breaking abnormally high waves, significant wave heights of 11.21 m and 12.39 m and significant wave periods of 13.6 sec and 14.3 sec at Akita and Yamagata GPS buoy sites, respectively, were observed along the Tohoku coast in the East Sea side of Japan. It was due to a well- and fast-developed low pressure passing through the East Sea. This paper describes how a low pressure could be grown so rapidly to tropical cyclone level in this time and numerical hindcast results for future forecast and engineering purpose. With respect to the meteorological condition, it is found that strong convective motion due to latent heat and water vapor from Tsushima Warm Current together with an accompanied front increases a pressure gradient at tropopause level accelerating the low growth. In the hindcast using an atmosphere-wave modeling system, two different initial and boundary condition data, NCEP FNL and JMA GSM, are used for applicability test. The result with NCEP FNL data shows a better agreement with observations in terms of surface winds. The observed peaks of significant wave height and period by Akita and Yamagata GPS buoy are captured well in both results. It is also found that the vertical resolution of initial and boundary condition data is important in atmospheric modeling; the higher vertical resolution tends to produce a deeper storm with lower central pressure and strong convective motion.