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Diagnostic Analysis of a RegionalHeavy Dust Storm Caused by Cold Front in HexiCorridor
CHENG  Feng, LI Guang-Lin, LIU  Gang, ZHANG Pei-Yan, YANG Xiao-Jun, SONG Xiu-Ling
J4    2009, 27 (3): 245-249.  
Abstract1746)      PDF(pc) (2304KB)(3111)       Save

Based on the basic observationaldata and automaticweather station data, a regionalheavy dust storm occurred onApril29,2009 inHexiCorridorwas analyzed from the causes of the synopticmeteorology, physics quantity fields and so on.The results show that itwas a duststorm thatcaused by the gale behind the cold front, and ithappened in the zone ofstrong pressure gradient. Groundmeteorological elements had a strong response to the outbreak of the dust storm, which can be used as a reference for forecast of dust storms. Therewas an obvious upwardmotion in the outbreak area ofduststorm with the lower level convergence and the high-leveldivergence. The frontogenesis function and helicity indicated the area of dust storm verywel.l

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Sta tistica l Character of Loca l Hail and Discussion About Specia l Hail Cloud Cell on the Northea st of Tibetan Plateau
LIU Chi-Guo, WANG Feng-Xiang, YANG Jian-Cai, YAN Gong-Xia, MAO Yu-Qin, CHENG  Feng
J4    2007, 25 (3): 10-16.  
Abstract1992)      PDF(pc) (495KB)(2168)       Save

Based on constant altitude p lane data of reflectivity factor from new generation weather radarwhich are interpolated with 3D - Barnes scheme, vertically integrated liquid water content (V IL) of hail cloud cell calculated with its theoreticalmodel, vertically integrated liquid water content density( V ILD) calculated by the ratio of V IL value to top height of hailcloud cell, the daily variation character, size distribution and the relations between the maximum diameter of hail on the ground (Rmax) and V ILmax, as well as V ILDmax of hailcloud cell during hail fall on the northeast of Tibetan Plateau are studied with statistic method. Results are as follows:(1)On the northeast part of Tibetan Plateau, hail fall was mainly in middle size hailstones ( diameter range: 5 - 20 mm) , and then smaller size hailstones ( diameter less than 5 mm) , larger hailstones ( diametermore than 20 mm) occurred less; (2) Local hail fall occurred mainly in the afternoon and evening, and there are two peak periodswhich are from 15: 00 to 16: 00 and from 20: 00 to 21: 00,and this result is accordant to the former research of Chen qian et al. on the whole but earlier in occurring period; ( 3) As a whole,there is a positive correlation between Rmax and V ILmax orV ILDmax, but the correlation between V ILDmax and Rmax is better; some difference exists in V ILDmax values of hail cloud cells corresponding to the same size hail but it is small and less than 0. 1 g. m - 3 ;( 4) The cone of silence for radar detecting, strong echo area leaning and echo overhanging of hail cloud cell are major factorswhich resulted in negative correlation between Rmax and V ILmax orV ILDmax.

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Analysis about a Regional Course of Hail
ZHANG Xin-Rong, WANG Ti-Wen, CHENG  Feng, SONG Xiu-Ling
J4    2004, 22 (4): 64-69.  
Abstract896)      PDF(pc) (132KB)(1468)       Save

A preliminary analysis on the first regional hail process which occurred on May 14 to 15 in 2004 was given,including its
atmospheric circulation,the background of previous climate and the field of physical quantities,and the conditions under which this
type of weather process occurs was established .This has certain instructing meaning to forcast such process accurately within short
and medium terms.

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