Investigating the robustness of the intraseasonal see-saw in the Indo-Pacific barotropic sea level across models
Résumé
An intraseasonal see-saw has been observed in the Indo-Pacific barotropic sea level anomaly during boreal winters. This see-saw carries a significant amount of energy and is crucial for the tropical sea level and angular momentum budget. Here, we evaluate the performance of several state-of-the-art ocean general circulation models (OGCMs), including the Modular Ocean Model (MOM), the Nucleus for European Modeling of the Ocean (NEMO), Massachusetts Institute of Technology general circulation model (MITgcm), and the HYbrid Coordinate Ocean Model (HYCOM) in reproducing the see-saw. Regardless of differences in model physics, forcings, setup, and resolution, all OGCMs simulate see-saw in the Indo-Pacific oceanic mass, making it a robust oceanic phenomenon. The models with horizontal resolutions ranging from 25 to 9 km, particularly those with higher resolution, are successful at simulating the qualitative characteristics of the see-saw. We show that a proper representation of the Indonesian straits is vital for a reasonable simulation of the see-saw. Furthermore, we show that the inclusion of the polar ocean in the models has little impact on the see-saw structure, implying that OGCMs with semi-global domain are appropriate tools for capturing the see-saw dynamics.