Importance of Resolving Mesoscale Eddies in the Model Simulation of Ningaloo Niño
Yaru Guo, Yuanlong Li, Fan Wang, Yuntao Wei, Qiong Xia
Abstract
Abstract Satellite observational data and a regional ocean model are used to understand the evolution of Ningaloo Niño (NN) anomalies near Western Australian coast. In observation and high‐resolution (~3 km) simulations, coastally trapped positive sea level anomalies (SLAs), originated largely from the Indonesian Throughflow, are transmitted westward by mesoscale eddies. Few eddies propagate long distances offshore due to dissipation, and as a result NN signatures are predominantly confined near the coast. In coarse‐resolution (~100 km) simulations that cannot resolve eddies, oceanic anomalies propagate swiftly as long Rossby waves with much weaker dissipation and more anomalies spread to the ocean interior. Eddy‐enhanced surface warming promotes surface latent heat release and mesoscale air‐sea interactions, which acts to damp NN surface warming. These processes are not resolved by coarse‐resolution models. This study highlights the importance of resolving mesoscale oceanic processes in the simulation and prediction of NN.