Analytical and numerical study of the 26 June 1998 orographic rainband observed in Western Kyushu, Japan
Analytical and numerical study of the 26 June 1998 orographic rainband observed in Western Kyushu, Japan
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1998年6月26日在日本九州西部观测到的地形雨带的分析和数值研究
DOI：
10.2151/jmsj1965.78.6_835
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发表时间：
2000
影响因子：
3.1
通讯作者：
Kazuo Manabe
中科院分区：
文献类型：
--
作者：
M. Yoshizaki;T. Kato;Yoshinobu Tanaka;H. Takayama;Y. Shoji;H. Seko;K. Arao;Kazuo Manabe
1998年6月26日，在一次名为X - BAIU - 98的野外实验中，观测到一个地形雨带（在本研究中称为长崎线）从日本九州西部的长崎半岛向东北方向延伸。这个雨带中的对流单体水平尺度约为5公里，持续时间约40分钟，以约10米/秒的速度向东北方向传播。它们在向东北方向上高度较深。在长崎线附近，观测到下层存在潮湿的对流不稳定大气，同时环境风包括近地面的南风以及在3 - 4公里高度的西南风急流。
利用日本气象厅的区域谱模式（RSM）和气象研究所的非静力云模式（NHM）对长崎线进行了数值模拟。RSM仅模拟出九州西部的一个弱降水区，而NHM再现了观测到的长崎线的许多特征。对地形、湿度和风廓线的敏感性实验表明，潮湿的对流不稳定大气、中尺度辐合以及在3 - 4公里处有强西南风急流且在对流层下层有强垂直风切变的风对于长崎线的形成至关重要。尽管长崎半岛上的山脉矮小，但在这样的环境场下能够形成有组织的降水带。
On 26 June 1998 during a field experiment called X-BAIU-98, an orographic rainband, called the Nagasaki line in this study, was observed extending northeastward from the Nagasaki Peninsula in western Kyushu, Japan. The convective cells in this rainband, which were about 5 km in horizontal scale and 40 min in duration, propagated northeastward at a speed of about 10 m s -1 . They were deep in height in a northeastward direction. Around the Nagasaki line, a moist convectively unstable atmosphere was observed in the lower layer together with environmental winds that included southerly winds near the surface and southwesterly jet at 3-4 km in height. Numerical simulations of the Nagasaki line were conducted using an operational Regional Spectral Model (RSM) of the Japan Meteorological Agency and a Nonhydrostatic Cloud Model (NHM) of the Meteorological Research Institute. While the RSM simulated only a weak precipitation area in western Kyushu, the NHM reproduced many characteristics of the observed Nagasaki line. Sensitivity experiments for topography, humidity and wind profiles showed that a moist convectively unstable atmosphere, mesoscale convergence, and winds having both a strong southwesterly jet at 3-4 km and a strong vertical wind shear in the lower troposphere are essential for the formation of the Nagasaki line. Although small and low, mountains on the Nagasaki Peninsula are capable of forming an organized precipitation band under such environmental fields.