1. Moisture Sources of the Tohoku Heavy Rainfalls in August 2022 and the Influences of Tropical Storms.
- Author
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Zhao, N., Wu, P., Manda, A., Guo, X., and Wang, B.
- Subjects
RAINFALL ,MOISTURE ,WEATHER ,STORMS ,TROPICAL storms ,WATER vapor transport - Abstract
In August 2022, the Tohoku region of Japan suffered three major heavy rainfall events, while one was related to an anticyclone, and the others were induced by a "Baiu‐like" stationary front. By using the Lagrangian backward trajectories, we found the moisture sources of the three events varied much due to the rapidly changing atmospheric conditions. In general, moisture from the Sea of Japan contributed the most in all events, while the western Pacific also played a certain role. Surprisingly, moisture from tropical storms and the East China Sea did not contribute much due to the along‐transport precipitation. But, based on forward‐traced trajectories, we confirmed that tropical storms did enhance moisture transport from subtropical regions via their southerly wind. Overall, this study highlights the role of the moisture gains nearby and the outer flows of tropical storms during heavy rainfalls in a northern region. Plain Language Summary: Heavy rainfalls hit northern Japan (i.e., the Tohoku region) from early‐ to mid‐August 2022, which were caused by a moving high‐pressure system, a rare north‐located "Baiu‐like" stationary front, and tropical storms. The highly accumulated moisture over Tohoku was supplied by the moistening over the marginal seas and the subtropical western Pacific, while the inland region also supplied a certain amount. Surprisingly, moisture carried by tropical storms (Songda, Trases, and Meari) and that from the East China Sea did not contribute much, because they were lost due to the precipitation during the transport. Most of the moisture was obtained nearby over the Sea of Japan. On the other hand, although storms did not contribute much moisture, their related wind fields did enhance moisture transport from moist‐rich regions to the Tohoku region. Key Points: Three heavy rainfalls occurred over the Tohoku region with varied moisture sourcesMoisture gains from the nearby Sea of Japan contributed the most, while the western Pacific played a secondary roleMoisture that was carried by tropical storms did not contribute much to the events but the storm‐induced southerly wind did [ABSTRACT FROM AUTHOR]
- Published
- 2023
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