Location and Intensity Changes of the North Equatorial Countercurrent Tied to ITCZ Under Global Warming

Abstract

Previous studies have suggested that global ocean circulation would be significantly changed under global warming, while the change of North Equatorial Countercurrent (NECC) and its mechanisms are still unclear. Here, we investigate the location and intensity changes of NECC under global warming based on CESM1 high-resolution long-term simulations from the perspective of the Inter-Tropical Convergence Zone (ITCZ), considering the close connection between NECC and ITCZ and well-established changes of ITCZ. It is found that the annual-mean NECC shifts equatorward of 0.39° and weakens by 21.71% in the RCP8.5 scenario at the end of 21st century. The NECC change is seasonally dependent, with maximum shift and weakening during spring, consistent with the changes of ITCZ. Both the location and intensity changes of ITCZ are important in the NECC changes, especially for spring. The weakening and equatorward shift of ITCZ contributes almost equally to the strongest decrease of spring NECC (47.63%).