著者

CHEN Wei GUAN Zhaoyong YANG Huadong XU Qi

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2020-014, (Released:2019-12-08)

被引用文献数

6

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The East Asian summer monsoon (EASM) and the Australian winter monsoon (AWM) are two important components of the Asian-Australian monsoon system during boreal summer. The simultaneous variations of these two monsoons would have remarkable impacts on climate in the Asian-Australian region. Using the reanalysis datasets, we investigate the mechanisms of variation and impacts of East Asian-Australian Monsoons (EAAMs). The singular value decomposition (SVD) is performed of the June-July-August (JJA) mean anomalous zonal wind for AWM as left field and JJA mean anomalous meridional wind for EASM as the right field after both El Niño-Southern Oscillation (ENSO) and India Ocean Dipole (IOD) signals are filtered out. Our results demonstrate that AWM and EASM are closely related to each other as revealed by the first leading SVD mode. The anomalously strong (weak) EAAMs correspond to anomalously strong (weak) AWM and EASM to the south of 30°N. When EAAMs are anomalously strong, cold sea surface temperature anomaly (SSTA) appears in regions near northern and northeastern coasts of Australia whereas the warmer SSTA appears in the northwestern tropical Pacific and South China Sea. The colder SSTA is associated with the upwelling of cold water from below induced by equatorial easterly anomalies, reinforcing the anticyclonic circulation over Australia through the Matsuno/Gill-type response whereas warm SSTA appears in the northwestern tropical Pacific and South China Sea as a result of oceanic response to the intensified northwest Pacific subtropical anticyclonic circulation. The EASM couples with AWM via the anomalous easterlies near equator in the Maritime Continent (MC) region and the slanted vertical anomalous circulations. In the years with strong EAAMs, precipitation decreases in northern Australia and over areas from the western Pacific to Bohai Sea and Yellow Sea of China. Meanwhile, the western MC and the southeastern China experience more than normal precipitation.

著者

JIAN Hong-Wen CHEN Wei-Ting CHEN Peng-Jen WU Chien-Ming RASMUSSEN Kristen L.

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2021-013, (Released:2020-12-02)

被引用文献数

5

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This study investigates the synoptic scale flows associated with extreme rainfall systems over the Asian-Australian monsoon region (90-160°E and 12°S-27°N). Based on statistics of the 17-year Precipitation Radar observations from Tropical Rainfall Measurement Mission, a total of 916 extreme systems with both the horizontal size and maximum rainfall intensity exceeding the 99.9th percentiles of the tropical rainfall systems are identified over this region. The synoptic wind pattern and rainfall distribution surrounding each system are classified into four major types: Vortex, Coastal, Coastal with Vortex, and None of above, with each accounting for 44 %, 29 %, 7 %, and 20 %, respectively. The vortex type occurs mainly over the off-equatorial areas in boreal summer. The coast-related types show significant seasonal variations in their occurrence, with high frequency in the Bay of Bengal in boreal summer and on the west side of Borneo and Sumatra in boreal winter. The None-of-the-above type occurs mostly over the open ocean, and in boreal winter these events are mainly associated with the cold surge events. The environment analysis shows that coast-related extremes in the warm season are found within the areas where high total water vapor and low-level vertical wind shear occur frequently. Despite the different synoptic environments, these extremes show a similar internal structure, with broad stratiform and wide convective core rain. Furthermore, the maximum rain rate locates mostly over convective area, near convective-stratiform boundary in the system. Our results highlight the critical role of the strength and direction of synoptic flows in the generation of extreme rainfall systems near coastal areas. With the enhancement of the low-level vertical wind shear and moisture by the synoptic flow, the coastal convection triggered diurnally has a higher chance to organize into mesoscale convective systems and hence a higher probability to produce extreme rainfall.

著者

早川 杏子 魏 志珍 初 相娟 玉岡 賀津雄 Kyoko Hayakawa Chih Chen Wei Xiang Juan Chu Katsuo Tamaoka

出版者

関西学院大学日本語教育センター紀要委員会

雑誌

関西学院大学日本語教育センター紀要 (ISSN:21870977)

巻号頁・発行日

no.5, pp.31-45, 2016-03