cm hpa hpa 2 45 N hpa ~ 12 Fig. 1 The observed rainfall distribution of Shanxi

28 3 2010 9 1006-7639 2010-03 - 0332-06 Journal of Arid Meteorology Vol. 28 No. 3 Sept 2010 1 1 2 1 3 1. 046000 2. 030404 3. 034000 2009 11 10 ~ 12 1 10 11 2300 hpa 3500 hpa 41 500 m 2 850 hpa 5FY - 2C 3 3 8 ~ 10 h P458. 1 + 1 A T213 1-2 3 1 4 2009 11 10 ~ 12 5 MM5 2003 11 9 08 12 08 3 d 4. 7 ~ 66. 0 mm 6 2006 1 3 10 mm 10 mm 15 20 ~ 30 mm 42 30 ~ 40 mm 23 40 ~ 50 mm 5 50 ~ 60 mm 2009 11 9 ~ 12 66. 0 mm 60. 8 48 cm 45 cm 42 7-15 cm 12 30 ~ 40 cm 37 20 ~ 30 cm 37 10 ~ 20 cm 2010-04 - 10 2010-07 - 14 1966 -. E - mail sxlyw1966@ foxmail. com 332 Journal of Arid Meteorology 2010 28 3 332-337

3 333 10 cm 10 30 11 2 500 hpa 7 3 3. 1 2009 11 8 20 500 hpa 2 45 N 9 08 500 hpa 1 2009 11 9 ~ 12 Fig. 1 The observed rainfall distribution of Shanxi Province on November 9-12 2009 9 20 2 10 08 10 08 11 08 10 20 3 2 10 1 500 hpa 5 11 20 10 11 08 12 08 8 20 10 08 10 11 10 08 2 9 20 12 2 10 1951 2 2009 10 11 11 12 Fig. 2 The daily series of the westerly circulation index from 11 October to 12 November 2009 3 2009 11 10 20 500 hpa Fig. 3 The 500 hpa height field at 20 00 on 10 November 2009 Journal of Arid Meteorology 2010 28 3 332-337 333

334 28 08 T - T d 1. 0 700 hpa 10 14 11 12 20 08 11 08 11 10 08 ~ 20 700 hpa 12 08 1 500 m 2 4 2 10 20 > 10 m /s 5 11 08 850 hpa 11 20 > 16 m /s 12 08 9 08 40 N 12 1 20 047. 5 hpa 13 2009 11 8 20 11 20 850 hpa 9 08 11 17 6 10 08 1 052. 5 hpa 11 14 11 14 20 12 08 4 2009 11 10 08 700 hpa Fig. 4 The 700 hpa height field observed at 08 00 on 10 November 2009 6 2009 11 10 20 Fig. 6 The surface synoptic chart at 20 00 on 10 November 2009 5 2009 11 10 20 850 hpa Fig. 5 The 850 hpa height field at 20 00 on 10 November 2009 3. 2 78 500 hpa 2 334 Journal of Arid Meteorology 2010 28 3 332-337

3 335 700 700 hpa 700 hpa hpa 9 10 11 700 hpa 850 hpa 10 20 11 11 2-10 ~ - 30 10-8 g cm - 2 hpa s - 1 850 hpa 9-5 ~ - 10 10-8 g 7 Fig. 7 2009 11 9 20 500 hpa The 500 hpa height field at 20 00 on 9 November 2009 cm - 2 hpa s - 1 9 3. 4 10 20 300 hpa 300 hpa 9 300 hpa 850 hpa 2 2 8 2009 11 10 20 500 hpa Fig. 8 The 500 hpa height field at 20 00 on 11 November 2009 3. 3 9 2009 11 10 20 300 hpa 2 Fig. 9 The 300 hpa height field at 20 00 on 10 November 2009 700 hpa 3. 5 FY - 2C 2009 11 10 02 ~ 08 FY - 2C 700 hpa 10 Journal of Arid Meteorology 2010 28 3 332-337 335

336 28 10 15 11 09 2 13 15 15 ~ 1 19 19 3 21 ~ 23 2 11 22 12 02 12 04 11 05 08 10 2009 11 10 03 12 02 FY - 2C Fig. 10 The evolution of FY - 2C satellite images from 03 00 November 10 to 02 00 November 12 2009 4 1 2009 11 9 ~ 12 10 11 4 1 500 m 2 850 2 300 hpa hpa 3 500 hpa 5 3 3 336 Journal of Arid Meteorology 2010 28 3 332-337

3 337 8 ~ 10 h 7. 1. A. 2010 36 2 144-146. 25 C. 10. 2002 470-479. 2. J. 2005 33 127-130. 3. J. 1986 3 35-37. 4 1999 25 11 37-39.. J. 1 119-123. J. 2010 36 8. J. 2001 21 2 108-112. 9. J. J. 2008 26 1 18-21. 11. J. 2008 26 1 64-68. 12. 2009 J. 2009 27 3 254-262. 13. J. 2006 24 1 28-33. 5. 2003 14. J. J. 2006 29 3 379-384. 2005 23 2 40-43. 6. 2006 1 15. 18 19 J. 2007 30 2 J. 2005 23 4 7-10. 44-47. Diagnostic Analysis of a Rare Autumn Snowstorm in Shanxi LIU Yaowen 1 ZHANG Hongying 1 SHI yunfei 2 YIN Zhenbao 1 MA Ziping 3 1. Changzhi Meteorological Bureau of Shanxi Province Changzhi 046000 China 2. Qingxu Meteorological Station of Shanxi Province Qingxu 030400 China 3. Xinzhou Meteorological Bureau of Shanxi Province xinzhou 034000 China Abstract Taking the snowstorm occurred in Shanxi Province from November 10 to 12 2009 for example this paper made a diagnostic analysis on causes of such extreme weather events from the circulation background vapor condition dynamic condition and cloud images change. The results are as follows 1 The snowstorm occurred when north hemisphere circulation presented high index characteristics and in most parts of China it was warmer 2 The configuring of convergence at the lower - layer and divergence at the level of 300 hpa caused vertical rise of airflow and formed dynamic condition for the snowstorm 3 The trough at tha level of 500 hpa over Hetao area leading the cold air moving from west to east and overlaying with the cold air from east at the bottom of polar vortex rising airflow from lower layer together with the frontal surface upper trough and shear line these all were main causes of this heavy snowstorm 4 There were two lower - level jets at 1 500 meters a strong east - wind wet jet and a south - wind which provided plentiful water vapor for the snowstorm area 5 According to the cloud images of FY - 2C satellite this heavy snowfall had close correlation with three cloud clusters in the troposphere the continuous formation and development of convective cloud clusters resulted in the strong snowfall lasting a long time. Key words snowstorm influencing system diagnostic analysis Journal of Arid Meteorology 2010 28 3 332-337 337