Observation of near-inertial wave reflections within the thermostad layer of an anticyclonic mesoscale eddy

Abstract

Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 37 (2010): L01606, doi:10.1029/2009GL041601.Moored current observations in the southwestern East/Japan Sea of 16.5 months duration clearly captured two episodes of downward phase propagation (upward energy propagation) of near-inertial waves (NIWs). Time series of temperature and velocity from the mooring and ancillary information indicate that the mooring was located near the center of an anticyclonic eddy during these events. Considering the typical vertical structure of quasi-permanent eddy features in the region, the observed downward phase propagation appeared to occur within the seasonal thermocline and upper thermostad of the anticyclonic mesoscale eddy. Ray tracing simulation of NIW using the observed subinertial currents suggests that the upward energy propagation is caused by the reflection of the NIWs within the thermostad of the anticyclonic eddy, where the effect of the vertical shear of subinertial horizontal currents is larger than the buoyancy effect in controlling the propagation of NIWs.This work was supported by grants from the Ministry of Land, Transport, and Maritime Affairs (Ocean Climate Variability Program), and the US NSF, grant OCE-0647949 to RWS