HOW STATIONARY ARE THE INTERNAL TIDES IN A HIGH RESOLUTION GLOBAL OCEAN CIRCULATION MODEL?

摘要

The stationarity of the internal tides generated in arnglobal eddy-resolving ocean circulation model isrnexplored using 5 years of model output. The simulatedrninternal tide is first compared with estimates obtainedrnfrom altimetric sea-surface heights. Both the model andrnobservations show strong generation of internal tides atrna limited number of “hot spot” regions with propagationrnof beams of energy for thousands of kilometers awayrnfrom the sources. The model tidal amplitudes comparernwell with observations near these energetic tidalrnregions. Averaged over these regions, the model andrnobservation amplitude estimates agree to approximatelyrn15% for the 4 largest semi-diurnal constituents and 23%rnfor the 4 largest diurnal constituents. Overall the RMSrnvariability in the M2 tidal amplitude is approximately .2rncm or larger over most of the Pacific and Indian Ocean.rnThe RMS variability of the M2 tidal amplitude canrnapproach the mean amplitude in weaker tidal areas suchrnas the tropical Pacific and eastern Indian Ocean, but it isrnsmall in relation to the mean amplitude over the hot spotrnregions. This suggests that the simulated internal tide isrnlargely stationary over the hot spot regions.