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The cross-shelf exchange between the Yellow and East China Seas (YECS) with the Kuroshio is important for vorticity, freshwater, and effluence balances of the regional and global oceans, the responses of which to future climate changes are estimated based on Max-Planck coupled model simulations under one historical (20C, 1970–2005) and two representative concentration pathway scenarios of global warming (RCP4.5 and RCP8.5) from 2006 to 2099. The results of the 20C simulation have shown prominent cross-shelf transports in the YECS, with annual mean outflow (OVT) and inflow (IVT) volume transports across the 100 m isobath of 3.97 Sv and 2.86 Sv (1 Sv = 106 m3 s−1), respectively. These annual mean OVTs (and their equivalent IVTs) are projected to increase by 0.42 Sv and 0.48 Sv from 2006 to 2099, at rates of 11.0% and 12.8% from the 2006–2016 means, under the RCP4.5 and RCP8.5 scenarios, respectively. The maximum rates of increase are found in winter to be at 13.2% and 19.9%, respectively. Analyses suggest that the winter monsoon has a long-term southwesterly change, forcing coastal currents to flow into the Yellow Sea along the China coasts to compensate for the increase of the southeastward surface Ekman transport. Due to increases of the Tsushima Strait and upper-layer Kuroshio transports, both the OVT and IVT across the 200 m isobath have onshore changes, resulting in net onshore transport increments of 0.30 Sv and 0.57 Sv under the RCP4.5 and RCP8.5 scenarios, respectively. The enhanced cross-shelf exchanges under future warming scenarios in the YECS suggest their potential importance in carbon transportation and storage.

The rectification of intraseasonal wind forcing on interannual sea surface temperature anomalies (SSTA) and sea level anomalies (SLA) associated with El Nino–Southern Oscillation (ENSO) during 1993–2016 are investigated using the LICOM ocean general circulation model forced with daily winds. The comparisons of the experiments with and without the intraseasonal wind forcing have shown that the rectified interannual SSTA and SLA by the intraseasonal winds are much weaker than the total interannual SSTA and SLA in the cold tongue, due to the much weaker rectified than the total interannual Kelvin and Rossby waves in the equatorial Pacific Ocean. The dynamics of the rectification are through the nonlinear zonal and vertical advection by the background currents, which produces downwelling equatorial Kelvin waves during El Nino. The meridional advection is much smaller than the zonal and vertical advection, suggesting that the rectification is not induced by the Ekman dynamics or the thermocline rectification. The rectified interannual Kelvin waves are found to be much smaller than reflected at the Pacific western boundary and those forced by the interannual winds, suggesting that the latter two play a much more important role in ENSO dynamics than the intraseasonal winds. The results of this study suggest an unlikely significant role of oceanic nonlinear rectification by intraseasonal winds during the onset and cycling of El Nino.

Previous studies have linked the rapid sea level rise (SLR) in the western tropical Pacific (WTP) since the early 1990s to the Pacific decadal climate modes, notably the Pacific Decadal Oscillation in the north Pacific or Interdecadal Pacific Oscillation (IPO) considering its basin wide signature. Here, the authors investigate the changing patterns of decadal (10-20 years) and multidecadal (> 20 years) sea level variability (global mean SLR removed) in the Pacific associated with the IPO, by analyzing satellite and in situ observations, together with reconstructed and reanalysis products, and performing ocean and atmosphere model experiments. Robust intensification is detected for both decadal and multidecadal sea level variability in the WTP since the early 1990s. The IPO intensity, however, did not increase and thus cannot explain the faster SLR. The observed, accelerated WTP SLR results from the combined effects of Indian Ocean and WTP warming and central-eastern tropical Pacific cooling associated with the IPO cold transition. The warm Indian Ocean acts in concert with the warm WTP and cold central-eastern tropical Pacific to drive intensified easterlies and negative Ekman pumping velocity in western-central tropical Pacific, thereby enhancing the western tropical Pacific SLR. On decadal timescales, the intensified sea level variability since the late 1980s or early 1990s results from the "out of phase" relationship of sea surface temperature anomalies between the Indian and central-eastern tropical Pacific since 1985, which produces "in phase" effects on the WTP sea level variability.