An ocean modeling study to quantify wind forcing and oceanic mixing effects on the tropical North Pacific subsurface warm bias in CMIP and OMIP simulations

Sea surface temperature (SST) bias in the climate models has been a focus past, but subsurface biases have not received much attention yet. In this study, tropical North Pacific (TNP) are investigated by analyzing CMIP6, CMIP5 and OMIP products, performing ocean model simulations. It is found that almost all CMIP simulations pronounced warm (SWB) northeastern (NETP), developments over past decade do indicate obvious improvements pattern magnitude from to latest version CMIP6. This SWB primarily caused deficiencies simulated wind stress curl (WSC) NETP, which too weak produce sufficient Ekman upwelling, also exists The uncertainties parameterizations of oceanic vertical mixing processes make great contribution, it demonstrated estimated diffusivities overestimated both upper boundary layer interior relationships between misrepresented conducting several ocean-only experiments, modified reducing stirring effect Kraus-Turner type bulk mixed-layer scheme, constrained using Argo-derived diffusivity. By applying these modifications schemes, greatly reduced NETP. consequences further analyzed. Because thermal structure NETP can influence circulations equatorial upper-ocean structure, large CMIP6 tends equatorward water transport TNP, upwelling ocean.