Diagnostic Analysis of a Snowstorm in Daxinganling Region
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Abstract:
The snowstorm process against the background of northeast cold vortex in the Daxinganling region on 13 and 14 November 2016 is analyzed using the routine observational data, FY2 satellite water vapor images, Doppler radar data and NCEP (1°×1°) reanalysis data with the resolution of 6 hours. The results indicate that the transversal trough from the rear of the upper cold vortex southward caused the drycold air southward and the lowlevel southwest jet in front of the cold vortex northwardjumping; moreover, the convergence which strengthened sharply provided the favorable circulation conditions for the snowstorm. The lowlevel southwest jet (≥20 m〖DK〗·s-1) as the moisture transport belt provided adequate water vapor for the snowstorm. The center of the vertical ascending motion was corresponding to the location of the center of the convergence and strengthened gradually, which offered the dynamic conditions for the snowstorm and promoted the development of ascending motion. The snowstorm process occurred against the background of the conditional symmetric instability where the moist potential vorticity MPV2<0 occurred, and the center of snowstorm was located in the intensive belt of MPV2 isolines and the area where MPV2 absolute value increased greatly. The water vapor image shows the dry seam and hatchet dark areas which is the characteristics of the dry intrusion. The radar echo shows that the lowlevel southeast jet was very significant. When the ultrastrong lower level southeast warm and moist air was vertical to the Daxinganling Mountains from the northeast to southwest, due to the topography effect, the ascending motion on the windward slope strengthened rapidly and the moisture convergence in lower layers strengthened and maintained, which offered the abundant moistures for the snowstorm, which was a major reason why the snowstorm was mainly distributed in the eastern foot of Daxinganling Mountains.
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.