Relationship between High-Impact Weather Events in Japan and Propagation of Rossby Waves along the Asian Jet in July 2004
Relationship between High-Impact Weather Events in Japan and Propagation of Rossby Waves along the Asian Jet in July 2004
复制标题
DOI：
10.2151/jmsj.87.139
复制
发表时间：
2009-02
影响因子：
3.1
通讯作者：
Takeshi Enomoto;H. Endo;Y. Harada;W. Ohfuchi
中科院分区：
文献类型：
--
作者：
Takeshi Enomoto;H. Endo;Y. Harada;W. Ohfuchi
2004年7月，暴雨在日本部分地区造成严重破坏，随后出现热浪。资料分析表明，梅雨期后期的降水和热浪事件都是由日本附近副热带高压（博宁高压）的加强引起的，而Rossby波沿着副热带急流的传播对博宁高压的强度有显著影响。从7月15日起进行了后测实验，以研究这些高影响天气事件的机制和可预测性。7月17日至18日，在日本海沿岸沿着包括酒田和福井在内的几个地点，通过高分辨率（21公里网格）全球后报模拟成功地模拟了局部风暴。这些降雨事件发生在顺时针平流的湿热空气细丝的前缘附近。7月20日，高分辨率后报模拟再现了异常高温。在83公里的中等分辨率下，虽然焚风较弱，但副热带高压的增强被再现。这一结果表明，与焚风相关的温度分布需要足够高的分辨率来分辨主要山脉。为了研究Rossby波传播和小笠原高压加强的可预报性，从2004年7月1日开始，使用中分辨率模式进行了25个成员的集合试验。结果表明，亚洲急流沿着分布的区域的可预报性是整个北方的两倍。这个案例研究表明，与Rossby波的传播沿着亚洲急流的小笠原高压的加强可以提前几个星期预测与集合预报在一个中等分辨率。
In July 2004, torrential rainfalls caused significant damages in parts of Japan, followed by heat waves. Our data analysis shows that both rainfall and heat wave events in late Baiu season were caused by the intensification of the subtropical anticyclone near Japan (Bonin high) and that intensity of the Bonin high was significantly influenced by propagation of Rossby waves along the subtropical jet. Hindcast experiments from 15 July were conducted to study the mechanisms and predictability of these high-impact weather events. On 17-18 July, localized rainfalls at a few locations along the coast of the Sea of Japan including Sakata and Fukui were successfully simulated in a high-resolution (21-km mesh) global hindcast simulation. These rainfall events were found to occur near the leading edge of a filament of moist and warm air advected clockwise. On 20 July, anomalously high temperature was reproduced in the high-resolution hindcast simulation. With a moderate resolution of 83 km, the intensification of the subtropical anticyclone was reproduced although the fohn was much weaker. This result indicates that temperature distribution associated with fohn requires a resolution high enough to resolve major mountains. In order to investigate the predictability of propagation of Rossby waves and intensification of the Bonin high, 25-member ensemble experiments from 1 July 2004 were conducted using the moderate-resolution model. It is shown that the region along the Asian jet has twice as long predictability as the entire Northern Hemisphere. This case study suggests that the intensification of the Bonin high associated with the propagation of Rossby waves along the Asian jet could be predicted a few weeks in advance with an ensemble forecast at a moderate resolution.