Formation Factors of 2004 Niigata-Fukushima and Fukui Heavy Rainfalls and Problems in the Predictions using a Cloud-Resolving Model
Formation Factors of 2004 Niigata-Fukushima and Fukui Heavy Rainfalls and Problems in the Predictions using a Cloud-Resolving Model
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DOI：
10.2151/sola.2005-001
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发表时间：
2005-01-01
期刊：
影响因子：
1.9
通讯作者：
Aranami, Kohei
中科院分区：
文献类型：
--
作者：
Kato, Teruyuki;Aranami, Kohei
2004年7月13日，在新潟 - 福岛地区观测到局部带状强降雨，2004年7月18日在福井地区也观测到此类降雨。这两个地区都位于日本列岛的日本海一侧。这些强降雨事件是由于低层潮湿空气和中层干燥空气的流入，导致梅雨锋区对流不稳定加剧的结果。中层空气相当温暖，并不比周围空气冷。这表明应该用对流不稳定而非潜在不稳定来研究强降雨的形成因素。
为了重现这些强降雨事件，使用水平网格为1.5千米的云解析模型进行了数值模拟。新潟 - 福岛的强降雨被很好地重现出来，而福井的强降雨则没有。福井案例的失败可能是由于对决定低层潮湿空气移动的日本海上风场分析不确定导致的。需要在很少进行高空探测的海上开发新的观测系统，以改进强降雨预测并防止此类失败。
Localized, band-shaped heavy rainfall was observed over the Niigata-Fukushima area on 13 July 2004 and over the Fukui area on 18 July 2004. Both areas are located on the Japan-Sea side of the Japan Islands. These heavy rainfall events were a result of an intensification of convective instability over the Baiu frontal zone, induced by the inflows of low-level humid air and middlelevel dry air. The middle-level air was considerably warm, not colder than the surrounding air. This indicates that the formation factors of heavy rainfall should be examined using convective instability, rather than potential instability.Numerical simulations using a cloud-resolving model with a horizontal grid of 1.5 km were carried out in an attempt to reproduce these heavy rainfall events. The Niigata-Fukushima heavy rainfall was reproduced well, while the Fukui heavy rainfall was not. This failure of the Fukui case could be the result of the uncertain analysis of the wind field over the Sea of Japan that determined the movement of low-level humid air. The development of new observation systems over the sea, where upper-air sounding is seldom operated, are required to improve heavy rainfall predictions and to prevent such failures.