17:15 〜 18:45
[AAS08-P13] Cold surges associated with the winter monsoons in the Maritime Continent using an isentropic analysis method
キーワード：Cold surge, Maritime Continent , Isentropic analysis, East Asian winter monsoon , Australian winter monsoon
The East Asian winter monsoon and the Australian winter monsoon accompany cold surges from the winter hemisphere. The cold surge blows into the Maritime Continent and induces the cross-equatorial flow. Previous studies have investigated the cold surges and the cross-equatorial flow to consider their impact on the weather and climate in the Maritime Continent. However, few studies investigated the cold surges associated with the East Asian winter monsoon and the Australian winter monsoon using unified method for comparing the features of both monsoons. For a better understanding of cold surges, we consider the monsoons or cold surges in the Maritime Continent as an cold air intrusion from the winter hemisphere and apply an isentropic analysis method to the cold surges. We investigate the cold surges during the East Asian winter monsoon and the Australian winter monsoon to derive climatology of the cold surges from the ERA5 reanalysis data for 20 years (2003–2022). In this study, we define cold air as cold airmass below an isentropic surface of 306 K.
During the East Asian winter monsoon, the cold air flows into the Maritime Continent from the South China Sea to the Arafura Sea. This main route mainly consists of seas surrounded by the islands. The cold air also covers the Makassar Strait and the low-altitude regions in the Malay Peninsula and the Sumatra Island. Along the route, high cold airmass flux persists, especially in the Java Sea. Although high cold airmass flux extends to the Banda Sea and the Arafura Sea, the cold airmass is rapidly lost in these seas. Cold airmass partly flows from the Pacific Ocean into the Band Sea and the Arafura Sea through the Molucca Sea. Meanwhile, during the Australian winter monsoon, the cold air flows from the north of the Australian continent into the Arafura Sea with high cold airmass flux. The cold air covers the Arafura Sea and the Banda Sea owing to the blocking effect of New Guinea Island. The cold air outflows mainly through the Molucca Sea to the Pacific Ocean and partly through the Flores Sea to the Java Sea. The region with high cold airmass flux extends from the Java Sea through the Karimata Strait to the South China Sea.
During the East Asian winter monsoon, the cold air flows into the Maritime Continent from the South China Sea to the Arafura Sea. This main route mainly consists of seas surrounded by the islands. The cold air also covers the Makassar Strait and the low-altitude regions in the Malay Peninsula and the Sumatra Island. Along the route, high cold airmass flux persists, especially in the Java Sea. Although high cold airmass flux extends to the Banda Sea and the Arafura Sea, the cold airmass is rapidly lost in these seas. Cold airmass partly flows from the Pacific Ocean into the Band Sea and the Arafura Sea through the Molucca Sea. Meanwhile, during the Australian winter monsoon, the cold air flows from the north of the Australian continent into the Arafura Sea with high cold airmass flux. The cold air covers the Arafura Sea and the Banda Sea owing to the blocking effect of New Guinea Island. The cold air outflows mainly through the Molucca Sea to the Pacific Ocean and partly through the Flores Sea to the Java Sea. The region with high cold airmass flux extends from the Java Sea through the Karimata Strait to the South China Sea.