200 likes | 406 Views
Structure and Formation Process of an Orographic Line-shaped Rainfall System during Baiu Season in Western Kyushu, Japan. Ayako Nakamura, Hiroshi Uyeda, (HyARC, Nagoya University, Nagoya, Japan) Osamu Morita, (Graduate School of Sciences, Kyushu University, Fukuoka, Japan)
E N D
Structure and Formation Process ofan Orographic Line-shaped Rainfall System during Baiu Season in Western Kyushu, Japan Ayako Nakamura, Hiroshi Uyeda, (HyARC, Nagoya University, Nagoya, Japan) Osamu Morita, (Graduate School of Sciences, Kyushu University, Fukuoka, Japan) Yasufumi Kitazaki, Hideki Beppu (Fukuoka District Meteorological Observatory, JMA, Fukuoka, Japan)
Goto Islands Goto line 2001/06/19/11:30JST Nagasaki Peninsula Isahaya line 1997/07/11/16:00JST Koshikijima Islands Koshikijima line 2002/07/01/12:20JST Three rainbands in Kyushu Z=2.0km Max crest : 461m Sapporo Max crest : 569m Japan Kyushu Max crest : 511m
How do these lines form from islands with low mountains in moist lower atmosphere? Goto line 2001/06/19/11:30JST Study on formation mechanism Study on formation mechanism ・Isahaya line and Koshikijima line ・Isahaya line and Koshikijima line →many analyses →many analyses ・Goto line ・Goto line →few analyses →few analyses PURPOSE To clarify 1. the structure of the 19 June 2001 Goto line 2. the formation process of the 19 June 2001 Goto line Objective
Fukuoka Hirado Sefuriyama observation sites Goto Islands the Sefuriyama radar data (the JMA operational radar) Sapporo upper-air soundings data (at Fukuoka) Japan JMA wind profiler data (at Hirado) Kyushu Meso Regional Analysis data
780m RH > 80% at surface convectively unstable LCL Environmental field Relative Humidity at surface ( by MANAL data)
north of north of north of north of Sefuri Mts. Sefuri Mts. Sefuri Mts. Sefuri Mts. Z=2.0km Z=2.0km over 130~200km Sefuri Mts. 12:50 12:50 16:00 11:40 16:00 09:40 16:00 11:40 12:50 11:40 09:40 cellular over over over over over over structure Sefuri Mts. Sefuri Mts. Sefuri Mts. Sefuri Mts. Sefuri Mts. Sefuri Mts. dissipation dissipation dissipation Sefuri Mts. Sefuri Mts. Sefuri Mts. Sefuri Mts. behavior and horizontal structure
09:40~11:40 north of Sefuri Mts. 16:00 11:40 12:50 09:40 over Sefuri Mts. 11:40~12:50 Sefuri Mts. Vertical structure Distance from Sefuriyama radar site [km]
Wind Profiler Froude number By Smolarkiewicz and Rotunno(1989) MANAL U0: a uniform horizontal wind N: Brunt-Vaisala frequency 25~29m/s h: top height of a mountain U0=15m/s,N=6.8×10-3/s,h=460m Fr = 4.8 (> 1) Upslope forcing by Goto Islands generation of convective clouds Wind profile and Froude number 19 JUNE 2001 09JST
about 28m/s northeastward convective cells Distance from Sefuriyama radar site [km]
over no high-mountains over mountains ( >1km height) upslope forcing Summary
Goto line 2001/06/19/11:30JST Isahaya line 1997/07/11/16:00JST Koshikijima line 2002/07/01/12:20JST Comparison of other lines (By Takeda et al. 1999) (By Nakamura et al. 2002)
north of Sefuri Mts. 16:00 11:40 12:50 09:40 over Sefuri Mts. Horizontal Feature
Vertical Feature 11:30
Z=2km Z=10km Z=6km Time variation
Isahaya line Takeda et al. 1999
Nakamura et al. 2002 Koshikijima line
U0: a uniform horizontal wind N: Brunt-Vaisala frequency h: top height of a mountain Froude number Froude number By Smolarkiewicz and Rotunno(1989) Small Fr(<1) horizontal detouring the obstacle Large Fr(>1) the vertically propagating-wave pattern