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ZHANG Shenglong, SUN Bo, CHEN Ping. 2023. Interdecadal Oscillations and Underlying Mechanisms Linking Tropical Pacific Sea Surface Temperature to East Asian Water Vapor Transport in December and February [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 47(4): 975−994. doi: 10.3878/j.issn.1006-9895.2202.21129
Citation: ZHANG Shenglong, SUN Bo, CHEN Ping. 2023. Interdecadal Oscillations and Underlying Mechanisms Linking Tropical Pacific Sea Surface Temperature to East Asian Water Vapor Transport in December and February [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 47(4): 975−994. doi: 10.3878/j.issn.1006-9895.2202.21129

Interdecadal Oscillations and Underlying Mechanisms Linking Tropical Pacific Sea Surface Temperature to East Asian Water Vapor Transport in December and February

  • Using NCEP/NCAR reanalysis data, ERA5 vertical integrated water vapor flux data, and NOAA monthly mean SST (sea surface temperature) data, the interdecadal variations in the relationship between central and eastern tropical Pacific SSTs and East Asian WVT (water vapor transport) in December and February from 1950 to 2019 were investigated. The finding reveals that the correlation between East Asian meridional WVT and central and eastern tropical Pacific SSTs in December was weak before the mid-1980s, becoming significantly positive afterward. In February, the correlation was significantly positive during 1950–1970 and 1990–2010. Interdecadal variations in the relationship between East Asian meridional WVT and central and eastern tropical Pacific SSTs in December stem from the increased influence of Pacific–East Asian (PEA) teleconnection and Northern Hemisphere circumglobal teleconnections on East Asian meridional WVT, driven by tropical SSTs after the mid-1980s. The PEA teleconnection and Northern Hemisphere circumglobal teleconnection would induce anomalous southerly WVT over East Asia, corresponding to warm SST anomalies in the central and eastern tropical Pacific. Unlike December, the relationship between the two factors in February was primarily modulated by the PEA teleconnection during 1950–1970 and 1990–2010. However, from 1971 to 1989, East Asian WVT was influenced by the circumglobal teleconnection in the Northern Hemisphere, corresponding to cold SST anomalies in the central and eastern tropical Pacific. This resulted in an insignificant relationship between the two factors during 1971–1989, as the above mechanism counteracted the effect of the PEA teleconnection. Furthermore, the impact of tropical Indian Ocean SSTs on East Asian WVT in December and February increased after 1990. In December, East Asian WVT was modulated by the Kelvin wave-induced Ekman divergence mechanism, while in February, it was influenced by the Walker circulation over the Indian Ocean, corresponding to warm SST anomalies in the tropical Indian Ocean.
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