Response of the southwestern Japan/East Sea to atmospheric pressure

The response of the southwestern Japan/East Sea (JES) to atmospheric pressure ( P atm ) and wind-stress ( τ ⇒ ) forcing is investigated by analyzing 2-year bottom pressure ( P bot ) data and coastal tide-gauge records. Coherence analyses between P bot data reveal that the response of the southwestern JES is nearly uniform at frequencies lower than 0.6 cycles per day (cpd). The Ulleung Basin (UB) average P bot ( P ¯ bot ) departs significantly from inverted-barometer (IB) response to the basin average P atm ( P ¯ atm ) at frequency bands from 0.2 to 0.7 cpd. The coherence between P ¯ atm and P ¯ bot has maximum value at 0.2 cpd. Multiple coherence analysis, applied with P ¯ atm and UB average τ ⇒ ( τ ⇒ ¯ ) as inputs and P ¯ bot as output, reveals that P ¯ atm is the most significant forcing, with a peak at frequencies between 0.2 and 0.3 cpd. A simple model [Garrett, 1983. Variable sea level and strait flows in the Mediterranean: a theoretical study of the response to meteorological forcing. Oceanologica Acta 6, 79–87; Lyu et al., 2002. Atmospheric pressure-forced subinertial variations in the transport through the Korea Strait. Geophysical Research Letters 29, 10.1029/2001GL014366] is used to investigate the limiting role of the three straits on the JES response to P atm . Coastal sea-level ( η ) data inside the JES as well as outside the straits demonstrate that the JES responds with a damped Helmholtz-like resonance. The resonance frequency predicted by this simple model is near the frequency of maximum coherence between P ¯ atm and η ¯ d , estimated from P ¯ bot by the hydrostatic approximation. Phase relations and response function gain between these variables confirm the applicability of this simple model to the JES for low-frequency bands below the Helmholtz-like resonance frequency. At higher frequencies, the response relaxes back toward IB, which suggests the mass field adjusts internally within the JES.