Heat budget of the western Pacific warm pool and the contribution of eddy heat transport diagnosed from HYCOM assimilation
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Using the high-resolution Hybrid Coordinate Ocean Model and the Navy Coupled Ocean Data Assimilation Global 1/12° Analysis (GLBa0.08), and the Objectively Analyzed Air–Sea Fluxes and the International Satellite Climatology Cloud Project products, we investigated the seasonal and interannual evolutions of heat budget, including the pseudo-heat content change, the net air–sea heat flux and the eddy heat transport (EHT), based on the time-dependent heat budget analysis in the western Pacific warm pool (WPWP). The results show that the pseudo-heat content change has significant semi-annual variation, which peaks in April–May and September. There is strong positive feedback between EHT and the net air–sea heat flux. EHT is important in balancing the sea surface heat flux into the WPWP. The seasonal EHT variability is dominated by its meridional component. On the interannual time scale, the zonal and vertical components of EHT show comparable amplitudes with the meridional one. The observed net air–sea heat flux in the WPWP is highly correlated with EHT and the pseudo-heat content change on the interannual time scale. The net air–sea heat flux leads the pseudo-heat content change by about half a month and leads EHT by about one month. The variations of the air–sea heat flux and EHT are connected to the El Niño Southern Oscillation events: during the development of El Niño (La Niña) events, the warm pool expanded eastward (retreated westward), the net air–sea surface flux into the WPWP increased (decreased) and EHT enhanced (weakened) significantly.
KeywordsEddy heat transport Heat budget Western Pacific warm pool ENSO Heat content
This work is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA11010103), the National Science Foundation of China (41525019, 41522601, 41521005), the State Oceanic Administration of China (GASI-IPOVAI-02), and the Open Project Program of the State Key Laboratory of Tropical Oceanography (grant LTOZZ1501). The OAFlux product was provided by the WHOI OAFlux Project (http://oaflux.whoi.edu/). The Argo product was provided by the International Argo Program (http://www.argo.ucsd.edu). The HYCOM product was obtained from the National Ocean Partnership Program (NOPP) (http://HYCOM.org). We would like to think Yan Li for providing HYCOM daily products.
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