Mesoscale variability and its seasonality in the Solomon and Coral Seas

High‐resolution (4 km) climatologically forced ocean model, validated by altimetry and glider data, is used to characterize the vertical and seasonal variations of mesoscale variability in the Solomon and Coral Seas. The highest eddy kinetic energy (EKE) in the southwest Pacific is found subsurface in the Gulf of Papua, at the depth of the low‐latitude western boundary current velocity core. Variability associated with the western boundary current, especially downstream of topographic obstacles, dominates the thermocline and intermediate level EKE. By contrast, surface EKE is generally enhanced in the southwest Pacific with a pronounced annual cycle that has a phase difference between small‐scale and large‐scale variability. Large mesoscale eddies account for most of the surface EKE and its annual modulation. The June maximum of surface EKE in the Solomon Sea and the December maximum in the Coral Sea can be accounted for by local instabilities of large‐scale currents. Small mesoscale eddies, predominantly cyclonic, are abundant in late winter (August to September), coinciding with the timing of deepest mixed layer and strongest vertical velocity. They contribute to the spatially uniform surface‐enhanced EKE over the top 100 m, not associated with the western boundary current. In the Coral Sea, small mesoscale eddies are generated mostly by open‐ocean surface baroclinic instabilities, while in the land‐bounded Solomon Sea near‐boundary instabilities and topographic generation are also important. Key Points A 4 km resolution nested model of the SW Pacific simulates AVISO SSH variability One class of eddies occur in the upper 100 m and are seasonally modulated Thicker, larger eddies occur on the flanks of the western boundary currents