Numerical study of the spatial distribution of the M2 internal tide in the Pacific Ocean

Abstract

As a first step toward numerical modeling of global internal tides, we clarify the distribution of the M2 internal tide in the Pacific Ocean using a three‐dimensional primitive equation numerical model. The numerical simulation shows that energetic internal tides are generated over the bottom topographic features in the Indonesian Archipelago, the Solomon Archipelago, the Aleutian Archipelago, and the Tuamotu Archipelago, the continental shelf slope in the East China Sea, and the mid‐oceanic ridges such as the Izu‐Ogasawara Ridge, the Hawaiian Ridge, the Norfolk Ridge, the Kermadec Ridge, and the Macquarie Ridge. The calculated spatial patterns of the M2 internal tide around the Hawaiian Ridge and the Izu‐Ogasawara Ridge agree well with the TOPEX/Poseidon altimetric observation. The conversion rate from the M2 surface to internal tide energy integrated over the whole model domain amounts to 338 GW (1 GW = 109 W), 84% of which are found to be generated over the prominent topographic features mentioned above. Reflecting the spatial distribution of the prominent topographic features in the Pacific Ocean, the energy level of the M2 internal tide in the western and central Pacific is 2–3 orders of magnitude higher than that in the eastern Pacific. This remarkable asymmetry shows that extensive microstructure measurements in the western and central Pacific are indispensable to determining the representative value of diapycnal mixing rates in the global ocean.