科研之友
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摘要
The subtropical-tropical cell (STC) in the Pacific Ocean is an ocean channel connecting the tropical and subtropical oceans. Due to the lack of ocean observation data, mostly available studies use ocean model data only, which limited the analysis of STC along a single latitude, and were less involved in the seasonal variation of STC along different latitudes. Based on Argo (Array for Real-time Geostrophic Oceanography) temperature and salinity data, GODAS (Global Ocean Data Assimilation System), SODA3.4.2 (Simple Ocean Data Assimilation 3.4.2), ORAS5 (Ocean ReAnalysis System 5), and NCEP (National Centers for Environmental Prediction) reanalysis data, the seasonal variations of STC along different latitudes in the Pacific as well as its mechanism are investigated in this study. Results show that along 10°~2°S and 2°~6°N, STC is stronger in spring and weaker in summer and autumn; at 7°~15°N, STC is stronger in summer and weaker in winter; at 15°~11°S, STC is stronger in winter and weaker in summer. The seasonal variation of STC is mainly driven by surface wind field and westward Rossby wave, and their relative contributions are different at different latitudes: at 10°S~6°N, the seasonal variation of STC is basically consistent with the seasonal variation of wind field, indicating that the seasonal variation of STC is mainly attributed to the sea surface wind forcing; At 15°~11°S and 7°~10°N, the STC variation lags behind the wind field for 3~4 months, and at 11°~15°N, the STC variation lags behind the wind field for 9 months. Therefore, the westward propagating of the Rossby wave plays an important role in the seasonal variation of STC than that of the local wind field. This study offered insightful view for in-depth understanding of the variation of STC and its impact on tropical ocean climate change. The diagnosis and comparative analysis of multi-source ocean reanalysis data also provides an important reference for the study of ocean circulation.
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