Based on data from observations, NCEP/NCAR reanalysis and the WRF simulations, two cases of intense snowstorms with blizzard conditions on 29 April 1983 and on 4 March 2007 in northeast China are investigated, in order to discuss the features of the environment conditions of these violent and persistent snowstorms which occurred over wild areas, and try to make accurate where and when it would occur. Results show, these snowstorms produced by the extensively deepened cyclones, which developed under the left side of the exit region of the southern jet and the right side of the entrance region of the northern jet at 300 hPa level, with the central cyclone sea level pressure drop rates of 1.2 hPa·h-1 (observation) and 0.71 hPa·h-1 (model grids) respectively. Wind shears in the troposphere are very remarkable, wind direction changed in clockwise with height, wind velocity increased with height, there exist an equally velocity layer from 4.5 to 8 km. Airflow divergent in the upper troposphere and convergent in the lower layer, updrafts developed due to the warmer air inflow and pumping caused by the divergence in the upper layer. Heavy snowfall and severe winds occurred at the northern and western parts of the cyclone, 10 min mean northerly surface winds greater than 20.8 m·s-1 occurred about 110 km away northwest of the central cyclone, with a snowfall rate of 20~35 mm·(12h)-1 (liquid water). The surface winds velocity and the snowfall accumulation increased to their highest values rapidly during the period of the sea level pressure dropped most quickly. A mesoscale warm and moist jet closed to the surface was formed at about 300 km away southeast of the central cyclone. Heavy snowfall accompanied by less severe winds of about 10.8~17.2 m·s-1 also presented within areas of 3~5 latitudes away from the cyclone in the northern part, surface winds velocity of most stations derived their maximize values just after the snowfall terminated. The 3D VAPOR visualization of the velocity from the GRIB grids and the WRF simulations show, severe surface winds are connected to the airflow among the two upper-level jets, suggesting that the surface winds energy originated from the upper troposphere aloft.
[1]Bosart L F, Sanders F.1986.Mesoscale structure in the megalopolitan snowstorm of 11-12 February 1983.part Ⅲ: A large-amplitude gravity wave [J].J Atmos Sci, 43(9): 924-939.
[2]Bosart L F, Seimon A.1988.A case study of an unusually intense atmospheric gravity wave [J].Mon Wea Rev, 116(10): 1857-1886.
[3]Bosart L F, Bracken W E, Seimon A.1998.A study of cyclone mesoscale structure with emphasis on a large-amplitude inertia-gravity wave [J].Mon Wea Rev, 126(6): 1497-1527.
[4]Davies-Jones R P, Burgess D W, Lemon L R, Purcell D.1978.Interpretation of surface marks and debris patterns from the 24 May 1973 Union City, Oklahoma tornado [J].MonWea Rev, 106(1): 12-21.
[5]FujitaT T.1981a.Tornadoes and downbursts in the context of generalized planetary scales[J].J Atmos Sci, 38(8): 1511-1534.
[6]FujitaT T.1981b.Five scales of airflow associated with a series of downbursts on 16 July 1980 [J].Mon Wea Rev, 109(7): 1438-1456.
[7]Hovanec R D, Horn L H.1975.Static stability and the 300mb isotach field in the Colorado cyclonegenetic area[J].Mon Wea Rev, 103(7): 628-638.
[8]Lemon L R.1998.Theradar"Three-Body Scatter Spike": An operational large-hail signature [J].Wea Forecasting, 13(2): 327-340.
[9]Sanders F, Gyakum J R.1980.Synoptic-dynamic climatology of the "bomb" [J].Mon Wea Rev, 108(10): 1589-1606.
[10]Uccellini L W.1975.A case study of apparent gravity wave initiation of severe convective storms[J].Mon Wea Rev, 103(6): 497-513.
[11]Uccellini L W, Kocin P J.1987.The interaction of jet streak Circulations during Heavy Snow Events along the East Coast of the United States [J].Wea Forecasting, 2(4): 289-308.
[12]Uccellini L W, Koch S E.1987.The synoptic setting and possible energy sources for mesoscale wave disturbances.Mon Wea Rev, 115(3): 721-729.
[13]Wilson J W, Wakimoto R M.2001.The discovery of the downburst: T.T.Fujita's contribution [J].Bull Amer Meteor Soc, 82(1): 49-62.
[14]Zha Ben, Shen Hangfeng, Guo Wenzheng, et al.2014.Analysis of gale process caused by an explosive cyclone [J].Plateau Meteor, 33(6): 1697-1704.DOI: 10.7522/j.issn.1000-0534.2013.00124.<br/>查贲, 沈杭锋, 郭文政, 等.2014.一次爆发性气旋及其诱发的大风天气分析[J], 高原气象, 33(6): 1697-1704.
[15]Gong Deji, Li Zhangjun.2001.On snowstorm disaster and its formation process in Inner Mongolia [J].Meteor Mon, 27(8): 19-23.<br/>宫德吉, 李彰俊.2001.内蒙古暴风雪灾害及其形成过程[J].气象, 27(8): 19-23.
[16]Huang Bin, Chen Tao, Kang Zhiming, et al.2011.Dynamic diagnosis and mechanism analysis of Yellow River cyclone induced Bohai storm tide[J].Plateau Meteor, 30(4): 901-912.<br/>黄彬, 陈涛, 康志明, 等.2011.诱发渤海风暴潮的黄河气旋动力学诊断和机制分析[J], 高原气象, 30(4): 901-912.
[17]Li Changqing, Ding Yihui.1989.A Diagnostic study of an explosively deepening oceanic cyclone over the northwest Pacific Ocean[J].Acta Meteor Sinica, 47(2): 180-190.<br/>李长青, 丁一汇.1989.西北太平洋爆发性气旋的诊断分析[J].气象学报, 47(2): 180-190.
[18]Li Ruqi, Tang Ye, Rouzi Aji.2015.Atmospheric circulation and water vapor characteristics of snowstorm anomalies in northern Xinjiang in 2010 [J].Plateau Meteor, 34(1): 155-162.DOI: 10.7522/j.issn.1000-0534.2013.00163.<br/>李如琦, 唐冶, 肉孜·阿基.2015.2010年新疆北部暴雪异常的环流和水汽特征分析[J].高原气象, 34(1): 155-162.
[19]Meng Xuefeng.2007.Studies on physical mechanism of snowstorm in Inner Mongolia and its forecasting technique [D].Lanzhou: Lanzhou University, 30.<br/>孟雪峰. 2007. 内蒙古暴风雪成因及预报技术研究[D]. 兰州: 兰州大学, 30.
[20]Shou Shaowen.1993.Mesoscale synoptic dynamics[M].Beijing: China Meterological Press, 226-230.<br/>寿绍文.1993.中尺度天气动力学[M].北京:气象出版社, 226-230.
[21]Sun Shuqing, Gao Shouting.1993.The influence of the activity of cold wave in East Asia on the explosive cyclone at its downstream [J].Acta Meteor Sinica, 51(3): 304-313.<br/>孙淑清, 高守亭.1993.东亚寒潮活动对下游爆发性气旋生成的影响[J].气象学报, 51(3): 304-313.
[22]Sun Yanhui, Li zechun, Shou Shaowen.2012.A mesoscale analysis of the snowstorm event of 3-5 March 2007 in Liaoning province[J].Acta Meteor Sinica, 70(5): 936-948.<br/>孙艳辉, 李泽椿, 寿绍文.2012.2007年3月3-5日辽宁省暴雪和大风天气的中尺度分析[J].气象学报, 70(5): 936-948.
[23]Sun Yanhui, Li Zechun, Shou SW.2015.An investigation into features and effects of the mesoscale gravity waves as in a snowstorm event.Acta Meteor Sinica, 73(4): 697-710.<br/>孙艳辉, 李泽椿, 寿绍文.2015.一次暴风雪过程中的中尺度重力波特征及其影响[J].气象学报, 73(4): 697-710.
[24]Wang Wenhui, Xu Xiangde.1979.The heavy snow process in district Xilingele and the analysis of "77·10"snowstorm [J].Acta Meteor Sinica, 37(3): 80-86.<br/>王文辉, 徐祥德.1979.锡盟大雪过程和"77·10"暴雪分析[J].气象学报, 37(3): 80-86.
[25]Yang Dasheng, Liu Yubin, Liu Shikuo.1980.Dynamical meteorology[M].Beijing: China Meterological Press, 208-209.<br/>杨大升, 刘余滨, 刘式适.1980.动力气象学[M].北京:气象出版社, 208-209.
[26]Yang Xia, Zhang Yunhui, Zhao Yizhou, et al.2015.Analysis on rare snowstorm in west of southern Xinjiang [J].Plateau Meteor, 34(5): 1414-1423.DOI: 10.7522/j.issn.1000-0534.2014.00063.<br/>杨霞, 张云惠, 赵逸舟, 等.2015.南疆西部一次罕见大暴雪过程分析[J].高原气象, 34(5): 1414-1423.
[27]Zhao Junrong, Yang Xue, Lin Xilu, et al.2013.Analyses on multi-scale system configuration and district of a disaster snowstorm [J].Plateau Meteor, 32(1): 201-210.DOI: 10.7522/j.issn.1000-0534.2012.00020.<br/>赵俊荣, 杨雪, 蔺喜禄, 等.2013.一次致灾大暴雪的多尺度系统配置及落区分析[J].高原气象, 32(1): 201-210.
[28]Zhuang Xiaocui, Cui Caixia, Li Boyuan, et al.2016.Analysis of warm zone mesoscale environmental and heavy snowfall drop zone in northern Xinjiang[J].Plateau Meteor, 35(1): 129-142.DOI: 10.7522/j.issn.1000-0534.2014.00132.<br/>庄晓翠, 崔彩霞, 李博渊, 等.2016.新疆北部暖区强降雪中尺度环境与落区分析[J].高原气象, 35(1): 129-142.
