Numerical study of the spatial distribution of the M-2 internal tide in the Pacific Ocean

As a first step toward numerical modeling of global internal tides, we clar ify the distribution of the M-2 internal tide in the Pacific Ocean using a three-dimensional primitive equation numerical model. The numerical simulat ion shows that energetic internal tides are generated over the bottom topog raphic features in the Indonesian Archipelago, the Solomon Archipelago, the Aleutian Archipelago, and the Tuamotu Archipelago, the continental shelf s lope in the East China Sea, and the mid-oceanic ridges such as the Izu-Ogas awara Ridge, the Hawaiian Ridge, the Norfolk Ridge, the Kermadec Ridge, and the Macquarie Ridge. The calculated spatial patterns of the M-2 internal t ide around the Hawaiian Ridge and the Izu-Ogasawara Ridge agree well with t he TOPEX/ Poseidon altimetric observation. The conversion rate from the M-2 surface to internal tide energy integrated over the whole model domain amo unts to 338 GW (1 GW = 10(9) W), 84% of which are found to be generated ove r the prominent topographic features mentioned above. Reflecting the spatia l distribution of the prominent topographic features in the Pacific Ocean, the energy level of the M-2 internal tide in the western and central Pacifi c is 2-3 orders of magnitude higher than that in the eastern Pacific. This remarkable asymmetry shows that extensive microstructure measurements in th e western and central Pacific are indispensable to determining the represen tative value of diapycnal mixing rates in the global ocean.