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[1] Transport variations with periods of 3 $ 5 days have been measured in the Korea (Tsushima) Strait by cross-strait cable voltage fluctuations and by direct, long-term measurement. Here we show that these variations can be explained in part by large-scale atmospheric pressure fluctuations over the East (Japan) Sea. First, using basin-wide averages of atmospheric pressure and sea surface height we show that sea surface height in the East Sea is not in isostatic equilibrium with atmospheric pressure, and that the imbalance is correlated with transport fluctuations. Second, we use a simple model to estimate the relationship between these quantities. The model displays a Helmholtz-like resonance in the observed range of periods and is in reasonable agreement with the observed transport variations.

The voltage‐derived transport in the Korea Strait from March 1998 to April 2002 reveals various temporal variations such as subinertial, monthly, seasonal, and interannual variations. The driving mechanisms of these temporal variations in the flows through the straits and the mean sea level of the East Sea (Sea of Japan) are investigated using a simple analytical barotropic model. The East Sea is simplified as a flat‐bottomed semienclosed basin, and it is forced by the atmospheric pressure, the along‐strait wind stress, and the sea level differences along the straits. Despite its simplicity this model explains most variations and helps us understand dominant driving forces on each timescale. At the subinertial periods of 2–10 days the atmospheric pressure dominantly drives the flows into or out of the East Sea due to a Helmholtz resonance, whose period is about 3 days, and the mean sea level cannot respond isostatically. The effects of the atmospheric pressure on the transport variations become weak at long periods because there is enough time for the East Sea to be drained or filled through the strait flows as its mean sea level responds isostatically. On the other hand, the changes in the adjusted sea levels outside the straits of the East Sea cause the pressure gradient forces along the straits and induce most of variations in the strait flows and the mean sea level at the monthly to interannual periods.

[1] High frequency (2 -20 days) sea level fluctuations, driven by atmospheric pressure changes, must be eliminated from TOPEX/POSEIDON altimeter data, else these data sampled at 10-day interval will suffer aliasing when interpreted as lower frequency variability of the subsurface pressure and circulation. A simple analytic Helmholtz-like model [Lyu et al., 2002], which explains successfully the nonisostatic sea level response in the Japan/East Sea (JES), is applied to correct the high-frequency sea level fluctuation effects on the T/P data. The model removes these pressuredriven fluctuations better than the standard inverse barometer (IB) method, leaving residuals smaller by about 10% in the corrected mean sea level (MSL) data used in this study. Because the maximum difference between the model correction and the IB correction can reach 10 cm, the impact of the correction choice is substantial. Moreover, uncorrected or IB corrected T/P along-track data contain substantial high frequency variability which can lead to 'trackiness' errors between crossing and neighboring tracks, contaminating their use for synoptic mapping. The model correction reduced the trackiness significantly better than the usual IB correction.

Analysis of high resolution hydrographic and current data revealed that the Korea Strait Bottom Cold Water (KSBCW) flowed into the Korea Strait from May to January and contained two temperature minimums, one in August/September and another in December/January. With the main current flows confined within 70 km of the Korean coast, maximum southwestward bottom currents corresponded with the temperature minimums. Time‐series of bottom current and temperature near the Korean coast clearly showed that the bottom temperature decreased as the bottom current strengthened. Seasonal variation of the KSBCW was linked to the combined effects of the barotropic and baroclinic current variations in the Korea Strait. The annual minimum bottom temperature of the KSBCW was associated with the maximum southwestward baroclinic component. The KSBCW had a secondary maximum southwestward bottom current and secondary minimum temperature in December/January when the Tsushima Warm Current (TWC), flowing into the East/Japan Sea (EJS), had the minimum volume transport.

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