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Kinematic Characteristics of mesoscale precipitation systems nearby the Baiu front by Doppler radar observations Kim, Kyung-Eak Department of Astronomy and Atmospheric Science, Kyungpook National University

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2 Contents Ⅰ. Introduction Ⅱ. Data acquisition Ⅲ. Analysis Method 1. VVP method 2. Calculation of vertical air velocity Ⅳ. Analysis Results Ⅴ. Summary and Conclusion

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Kyungpook National University 3 Ⅰ. Introduction

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Kyungpook National University 4 1. Previous Studies Takeda and Seko (1986) Study of 3-dimensional structures and propagation prosess of mesoscale rain band using data based on radar observation. Ninomia et al (1988) notified that fluctuation of Chang-ma(Baiu or Maiu) front has organization according Orlanski classification.

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Kyungpook National University 5 Iwasaki and Takeda (1993) Study of structures and states of mesoscale cloud clusters moving over the Chang-ma front zones Ishihara et al (1995) Analysis properties of heavy mesoscale rain band over the Chang-ma front using the Doppler radar. Takahashi et al.(1996) Analysis of both mesoscale and convectice scale features of Baiu frontal heavy rainfall.

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Kyungpook National University 6 Bessho et al.(1999) Multi-scale structure of Baiu front Kanada et al.(2000) study of rainfall enhancement of band-shaped convective cloud system in the downwind side of Yaku-shima

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Kyungpook National University 7 2. Purpose of study To Study kinematic characteristics and structure of mesoscale precipitation developed on the Baiu front using a Doppler radar observations

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Kyungpook National University 8 Ⅱ. Data acquisition

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Kyungpook National University 9 1. Observation area The location of Doppler radar and radiosonde observation site Radar data : Yakushim, Japan Sounding data : Minamita, Japan

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Kyungpook National University 10 Case 1: 1600 LST, LST, 22, June, 1996 Case 2: 1900 LST, LST, 06, July, observation period 3. elevation angles 0.5 o, 1.6 o, 2.8 o, 4.2 o, 6.1 o, 8.9 o, 12.9 o, 17.9 o, 24.0 o, 31.0 o

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Kyungpook National University The characteristics of MRI-X band radar installed at Minamita Parameter Parameter Characteristic ValueCharacteristic Value frequency (MHz) frequency (MHz) wavelngth (cm)wavelngth (cm) 3 Maximun range (km)Maximun range (km) 75 km75 km Nyquist velocity (ms-1)Nyquist velocity (ms-1) ±15.29 ±15.29 Pulse repetition frequency (Hz)Pulse repetition frequency (Hz) Number of range gates Number of range gates range resolution (m)range resolution (m) 250m 250m Azimuth resolution (degree)Azimuth resolution (degree) data resolution velocity (ms-1) reflectivity (dBZ) data resolution velocity (ms-1) reflectivity (dBZ)

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Kyungpook National University 12 Ⅲ. Analysis Method

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Kyungpook National University VVP(Volume Velocity Processing) The data processing geometry of VVP and TVP method. The △ h and D are the vertical depth and diameter of slice, respectively. Here the 250 m and 45 km, respectively.

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Kyungpook National University 14 Kinematical parameters estimated by VVP method

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Kyungpook National University Calculation of vertical air velocity used anelastic mass continuity equation (Ogura and Phillips, 1962)

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Kyungpook National University 16 Ⅳ. Analysis Results

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Kyungpook National University LST, 21, June, 1996 ~ 0700 LST, 22, June, 1996 Case Ⅰ

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Kyungpook National University 18 The surface weather map at (a) 0000 UTC(9 LST) 21 June, and (b) 1200 UTC(21 LST) 21 June, (a) (b)

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Kyungpook National University 19 Infrared satellite image at (a) 1800 LST 21 June, (b) 2100 LST 21 June. (c) 0000 LST 22 June, and (d) 0300 LST 22 June, 1996 (a)(b) (c)(d)

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Kyungpook National University 20 Three hourly rainfall amounts around Yakushima from 1500 LST 21 June, 1996 to 0900 LST 22 June, 1996 (Case 1).

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Kyungpook National University 21 The vertical profiles of potential temperature, equivalent potential temperature and saturated equivalent potential temperature at (a) 1500 LST, 21, June, (b) 2100 LST, 21, June and (c) 0900 LST, 22, June, respectively. And the vertical profiles of (d) temperature, (e) wind speed and (f) wind direction at periods of (a), (b) and (c).

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Kyungpook National University 22 Time-height cross sections of wind vector drove with a VVP processing diameter of 45 km and processing slice depth of 200 m.

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Kyungpook National University 23 Time-height cross sections of (a) reflectivity (dBZ) and (b) divergence (1.0×10 -4 s -1 ) from 1600 LST 21 to 0700 LST 22 June, 1996.

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Kyungpook National University 24 The vertical profiles of (a) radar reflectivity, (b) divergence, (c) vertical air velocity, and (d) fall velocity at 1800 LST-1900 LST 21 June, 1996.

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Kyungpook National University 25 The vertical profiles of (a) radar reflectivity, (b) divergence, (c) vertical air velocity, and (d) fall velocity at 2100 LST, LST, 22, June, 1996

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Kyungpook National University 26 The vertical profiles of (a) radar reflectivity, (b) divergence, (c) vertical air velocity, and (d) fall velocity at 0200 LST LST, 22, June, 1996.

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Kyungpook National University 27 The vertical profiles of (a) radar reflectivity, (b) divergence, (c) vertical air velocity, and (d) fall velocity at 0400 LST-0430 LST, 22, June,1996.

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Kyungpook National University 28 The vertical profiles of (a) radar reflectivity, (b) divergence, (c) vertical air velocity, and (d) fall velocity at 0500 LST LST, 22, June, 1996.

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Kyungpook National University 29 Time-height cross sections of divergence components (×10 -4 s -1 ) parallel (a) and perpendicular (b) to the front of Case 1, respectively.

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Kyungpook National University 30 Time-height cross sections of vertical wind shear components (×10 -3 s -1 ) parallel (a) and perpendicular (b) to the front of Case 1, respectively.

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Kyungpook National University 31 Case Ⅱ 1900 LST, 05, July, 1996 ~1600 LST, 06, July, 1996

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Kyungpook National University 32 The surface weather maps at (a) 1200 UTC (2100 LST) 5 July, 1996 and (b) 1200 UTC (2100 LST) 6 July, (a) (b)

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Kyungpook National University 33 GMS IR images with 3 hour intervals from 1800 LST 5 July, to 1500 LST 6 July, 1996 (Case 2). (a) 1800 LST 5 July 1996 (b) 2100 LST 5 July 1996 (c) 0000 LST 6 July 1996 (d) 0300 LST 6 July 1996

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Kyungpook National University 34 continued (e) 0600 LST 6 July 1996 (f) 0900 LST 6 July 1996 (g) 1200 LST 6 July 1996 (h) 1500 LST 6 July 1996

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Kyungpook National University 35 Three hourly rainfall amounts around Yakushima from 1800 LST 5 July, 1996 to 1800 LST 6 July, 1996 (Case 2).

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Kyungpook National University 36 The vertical profiles of potential temperature (θ), equivalent potential temperature (θ e ), and saturated potential temperature (θ es ) at (a) 2100 LST 5 July, (b) 0900 LST 5 July and (c) 1500 LST 6 July, and the vertical profiles of (d) temperature, (e) wind speed and (f) wind direction at period of (a), (b), and (c), respectively.

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Kyungpook National University 37 Time-height cross sections of (a) reflectivity (dBZ) and (b) divergence(1.0x10 -4 s -1 ) from 1900 LST 5 to 1600 LST 6 July, 1996.

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Kyungpook National University 38 Time-height cross sections of (a) fall velocity (ms -1 ) and and (b) vertical velocity of air (ms -1 ).

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Kyungpook National University 39 Time-height cross sections of divergence components(×10 -4 s -1 ) parallel (a) and perpendicular (b) to the front of Case 2, respectively.

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Kyungpook National University 40 Time-height cross section of vertical wind shear (×10 -3 s -1 ) of Case 2.

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Kyungpook National University 41 Schematic diagram of precipitation structure developed on Baiu front of Case 1 and 2. The C1 represents a convective system ahead of the Baiu front, and the C1, and C2 are convective systems developed on the line of wind shear. The S1 and S2 represent a large stratiform cloud system with bright band and stratiform cloud on the shear line, respectively. Case 1Case 2

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Kyungpook National University 42 The vertical profiles (a) radar reflectivity (dBZ), (b) divergence (×10 -4 s -1 ), (c) vertical velocity of air (ms -1 ), and (d) fall velocity (ms -1 ) averaged from 1900 LST to 2200 LST 6 July, 1996.`

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Kyungpook National University 43 The vertical profiles (a) radar reflectivity (dBZ), (b) divergence (×10 -4 s - 1 ), (c) vertical velocity of air (ms -1 ), and (d) fall velocity (ms -1 ) averaged from 1145 LST 6 to 1600 LST 7 July, 1996.

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Kyungpook National University 44 Time height cross sections of vertical wind shear components (× s -1 ) parallel (a) and perpendicular (b) to the front of Case 2, respectively.

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Kyungpook National University 45 V. Summary and conclusions

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Kyungpook National University 46 1). The present study shows that the precipitation structure and kinematic characteristics and structure of the precipitation developed along the Baiu front highly depends on its type, that is, cold-type or warm-type. 2). The analyzed Baiu frontal precipitation system were found to be composed of three different systems: convective system whose top higher than the melting level, stratiform cloud with bright band, and clouds developed along the vertical shear line of the horizontal wind.

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