Vol.27 No.2(4) [2005]

Formation of convergent cloud band over western Japan Sea in winter

Michiko IKEDA, Keita IGA


When cold airmass outbreaks from Eurasian Continent in winter, convergent cloud band is often formedover western Japan Sea. This convergent cloud band is formed in the lee side of the mountains located in northern Korean Peninsula, and it is often characterized by a local front. In order to investigate the formation condition of this convergent cloud band and its frontal structure, numerical experiments by ARPS are performed. A numerical experiment with constant sea surface temperature simulated a cloud band in the lee of the mountain, but it is not accompanied by a frontal structure. On the other hand, a numerical simulation with sea surface temperature gradient successfully simulated a cloud band with a secondary stable layer or a kind of ``front''. When a mountain is situated in the uniform wind and latent heat is supplied from the sea surface, convergent cloud band may be generated, but this condition is not enough to construct a frontal structure. The gradient of the sea surface temperature is necessary to form the frontal structure.