2:15 PM - 2:30 PM
[ACG36-09] Mesoscale atmosphere–ocean coupling resolved in global coupled simulations with NICOCO
Keywords:atmosphere - ocean coupled model, high-horizontal resolution, air-sea interaction
Thanks to the advancement in the high-performance computing, a high-resolution global coupled simulation has become feasible. By using the Supercomputer “FUGAKU”, we conducted 40-day global coupled simulations with NICOCO, which consisted of the atmospheric model (NICAM) with 3.5km resolution and ocean model (COCO) with 0.1° resolution, along with some lower-resolution simulations. The present study investigates the resolution dependence of air-sea interaction processes focusing on the wintertime subtropical and midlatitude regions.
The lead-lag correlation between SST and surface heat fluxes suggests that mesoscale SST perturbations thermally force the atmosphere over the Kuroshio Extension (35°N) and subtropical front regions (25°N) in the North Pacific when the horizontal resolution of the ocean component is 0.1°. Additionally, the 3.5 km-resolution atmospheric component exhibits a stronger response to mesoscale ocean forcing compared to the 14 km-resolution component. On the contrary, the SST variability is mostly driven by atmospheric forcing in coupled simulations with a 0.25° ocean component. These features are largely consistent over the globe, including the South Pacific, North Atlantic and Indian Ocean. Therefore, high-resolution coupled simulations could possibly improve the representation in the larger-scale circulations because, as argued in the previous studies, ocean eddies and the western boundary currents significantly modulate synoptic-scale atmospheric disturbances. Long-term simulations should be conducted to quantify the roles of the fine-scale air-sea interaction on the global circulation.
Acknowledgements: This work was supported by MEXT as “Program for Promoting Researches on the Supercomputer Fugaku” (JPMXP1020200305) The simulations were conducted by using Supercomputer Fugaku provided by the RIKEN Center for Computational Science (Project ID: hp200128, hp210166, hp220167, hp230108, hp240179).
The lead-lag correlation between SST and surface heat fluxes suggests that mesoscale SST perturbations thermally force the atmosphere over the Kuroshio Extension (35°N) and subtropical front regions (25°N) in the North Pacific when the horizontal resolution of the ocean component is 0.1°. Additionally, the 3.5 km-resolution atmospheric component exhibits a stronger response to mesoscale ocean forcing compared to the 14 km-resolution component. On the contrary, the SST variability is mostly driven by atmospheric forcing in coupled simulations with a 0.25° ocean component. These features are largely consistent over the globe, including the South Pacific, North Atlantic and Indian Ocean. Therefore, high-resolution coupled simulations could possibly improve the representation in the larger-scale circulations because, as argued in the previous studies, ocean eddies and the western boundary currents significantly modulate synoptic-scale atmospheric disturbances. Long-term simulations should be conducted to quantify the roles of the fine-scale air-sea interaction on the global circulation.
Acknowledgements: This work was supported by MEXT as “Program for Promoting Researches on the Supercomputer Fugaku” (JPMXP1020200305) The simulations were conducted by using Supercomputer Fugaku provided by the RIKEN Center for Computational Science (Project ID: hp200128, hp210166, hp220167, hp230108, hp240179).