Synoptic-Scale Variations in the Polar Air-Mass Transformed over the Japan Sea

Abstract

The present report studies synoptic-scale variations of the polar air-mass transformed over the Japan Sea, during the ''East Japan Sea Observation'' in the winters of 1976 and 1977. Rawinsonde observation data at a research vessel are used, in addition to data at operational upper observation stations and the objective analysis data.The multi-layer structure of the transformed air-mass, including the unstable lowest layer and the mixed layer capped by the stable layer, is formed in the transformed airmass over the Japan Sea. The mixed layer, which includes the sub-cloud layer and the cloud layer, is characterized by nearly vertically-uniform equivalent potential temperature. The height of the mixed layer top is 1000-1500 m, on the average, over the Japan Sea. The height increases toward the south, and reaches 2000-2500 m over the coastal area of Japan.The height of the mixed layer top, and the apparent total heat source in the transformed air-mass, vary widely in association with the synoptic-scale changes of polar-air outbreak. The height of the mixed layer top tends to increase in association with the increase of the apparent total heat source in the mixed layer, and the decrease of the vertical stability in the lower-middle troposphere. The snowfall depth over the coastal area of Japan tends to increase in association with the increase of the apparent total heat source over the Japan Sea. The important synoptic conditions for the occurrence of the heavy snowfalls are the intense polar-air outbreak, and/or the passage of the cold vortex or the deep cold trough over the Japan Sea.

Climate and music (Toward development of the interdisciplinary climate and cultural understanding education of ESD with special attention to the seasonal cycle and seasonal feeling around Japan and Europe)

“…In that situation, the huge amounts of sensible heat and latent heat are supplied from 115 the underlying sea along the path of the very cold air from the continent, and the convective mixed layer due to the shallow cumuli develops over the sea. These result in the climatologically huge snowfall in the Japan Sea side of the Japan Islands in winter (e.g., Ninomiya 1968Ninomiya , 2006Ninomiya , 2007.…”

Satellite evidence of wintertime atmospheric boundary layer responses to multiple SST fronts in the Japan Sea

“…The defined line extends from the Eurasian coast on the east of Vladivostok, goes through the meandering Polar Front, and get to the northern Japanese coast, where wind speed is especially large (Figure 1b). Because the line passes close to the northward warm water intrusion (136.5–137.0°E), this line allows us to consider flow from warm to cold water, as well as the flow from cold to warm water which has been mostly considered in studies of the Japan Sea [e.g., Ninomiya , 2007]. Additionally, surface and upper air wind observations are available at a downwind station S whose location closely corresponds to the origin of the trajectories.…”

“…In Figures 3a and 3b, the p *‐coordinate system is used, which is defined as: where p is the pressure and p s is the sea level pressure. This coordinate is suitable for displaying near surface observations and has been effectively adopted by many studies when the pressure field varies significantly over the study area [e.g., Ninomiya , 2007].…”