Squall Line Like Convective Snowbands over the Sea of Japan

[摘要] This paper describes the internal structure of two convective snowbands, deduced by using mainly single-Doppler radar data, which developed over the Sea of Japan in winter, traveled nearly perpendicularly to their orientation, and showed common features.A typical snowband was formed in a convective mixed layer 4km deep over the relatively warm sea surface in the early stage of a cold-air outbreak. This snowband was a multicell system which contained two or three echo cells in a vertical plane normal to its orientation. Each echo cell developed aloft in the forward portion of the snowband and became a mature echo cell in the middle of the snowband. The upper portion of old cells remains in a small anvil with low reflectivity below the stable layer in the rear part of the snowband. The snowband had the main updraft in its forward portion. The updraft tilted upshear and penetrated the stable layer above the convective mixed layer. There was a descending current from rear to front relative to the snowband in the lower half of the anvil. Snow particles evaporated in the downdraft. The leading edge of the downdraft was observed on the ground as a gust front with a severe gust and a drop in temperature of -1°C.The circulation and maintenance mechanism of the convective snowbands was similar to those of tropical and midlatitude squall lines.

[学科分类] 大气科学