Contrastive analysis of instability mechanism of two extra torrential rain events in Yunnan Province

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1 JOURNAL OF NATURAL DISASTERS Vol. 24 No. 2 Apr DOI: /j. jnd NCEP 1 1 MM5 V3. 6 T - ln P LI CAPE CIN EPV TV A Contrastive analysis of instability mechanism of two extra torrential rain events in Yunnan Province ZHU Li 1 ZHANG Tengfei 1 DING Zhiying 2 1. Yunnan Meteorological Observatory Kunming China 2. School of Atmospheric Sciences Nanjing University of Information Science & Techndgqy Nanjing China Abstract 1 1 NCEP reanalyzed data and MM5V3. 6 numerical model were used to simulate two typical local extra torrential rain events happened in Yunnan Province which located in lower latitude plateau of china. High space-time resolution data from MM5V3. 6 numerical model was utilized to draw T-ln P diagram and calculate LI index CAPE index CIN index and equivalent potential vortex EPV. These physical quantities were used to analyze the conditional instability convective instability and conditional symmetrical instability of the two local extra torrential rain events. Results indicate that the two local extra torrential rain events have different instability mechanism. When atmosphere is stratification stable and convective stable or weak unstable the conditional symmetrical instability may lead to heavy precipitation. Key words disastrous extra torrential rain numerical simulation conditional instability convective instability conditional symmetrical instability CMAYBY CB YB julia_ @ 163. com

2 MM5 V mm h mm 1 a 10 mm mm /h h mm 7 10 mm h 51 mm 1 h h b Fig. 1 1 a b Hourly rainfall recorded by meteorological stations in Chuxiong a and Kunming b MM5V E 25 N km 18 km Graupel reisner Mix Phase Graupel gsfc 1 Betts - Miller 2 Grell MRF Cloud h 2 b2 a A B

3 E 26 N h 2 d2 c E N mm 23 2 mm h a b mm h c d mm Fig. 2 Actual and simulated accumulated rainfall in two interval unit mm 2 10 LI m 500 hpa T' 500 hpa T 500 LI = T T'. 1 LI LI < 0

4 hpa 1 LI < 0 LI = 0 LI > T - ln P 3 3 h T' > T LI = - 2 < ~ 550 hpa Fig T - ln P Diagam of T - ln P simulated by controlling test at T for the air of torrential rain center h T' T LI = hpa ~ Fig T - ln P Diagram of T - ln P simulated by controlling test at T for the air of torrential rain center

5 K 12 K 13 { > 0 θ = 0 z < 0. θ e h 800 ~ 550 hpa θ e V θ e < 0 z 5 a CAPE 598J /kg CIN θ e 15 V θ e = 0 z 5 b CAPE 9 J /kg CIN 0 θ e h 800 ~ 700 hpa < 0 θ z e 5 c CAPE 8 J /kg 10 J /kg 4 θ e = 0 5 d z CAPE 53J /kg CIN 1 J /kg CSI 5-6 CSI Moore 14 EPV CSI EPV EPV EPV Moore EPV EPV = - gη g θ e g η g x y p θ e 2 3

6 K a b c d Fig. 5 Longitudinal vertical profile of equivalent potential temperature through simulated torrential rain center unit K Fig. 6 6 PVU a b Longitudinal vertical profile of equivalent potential vortex through simulated torrential rain center unit PUV EPV N N EPV 6 a N 550 ~ 350 hpa EPV EPV 400hPa - 1PVU 6 b EPV EPV EPV EPV

7 N - 26 N 650 ~ 300 hpa EPV EPV EPV PVU 7 a EPV EPV EPV N 45 ~ 250 hpa EPV PVU 7 b EPV 7 c EPV 7 d Fig. 7 7 PVU a b c d Longitudinal vertical profile of equivalent potential vortex through simulated torrential rain center unit PVU EPV EPV EPV h EPV EPV EPV EPV LI CAPE CIN T - ln P LI θ e

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