Intraseasonal to seasonal variability of the intermediate waters along the K uroshio path east of T aiwan

The variability of the intermediate water (IW) east of Luzon and Taiwan is investigated using data acquired from moored instrumented lines and shipboard hydrographic and current velocity surveys. The IW is defined as the water mass with a local salinity minimum along the Kuroshio path. An empirical formula is developed to estimate the IW salinity minimum east of Taiwan using temperature measurements around 580 m depth. Properties of the IW east of Taiwan vary greatly as a result of variable contributions from three water masses including the high‐salinity South China Sea Intermediate Water (SCSIW), the low‐salinity North Pacific Intermediate Water (NPIW), and the intermediate‐salinity Kuroshio Intermediate Water (KIW). Our analysis concludes that NPIW is predominantly found east of Taiwan, and the northward transport of KIW from northeast of Luzon to east of Taiwan is not a steady process. Concurrent mooring measurements at these two locations enable us to correlate the variations of the layer thickness of the Kuroshio near its origin (KLT o ) northeast of Luzon to the nature of the IW east of Taiwan. When the Kuroshio is deep, i.e., large KLT o , KIW is transported northward across the Luzon Strait, where its salinity increases presumably due to turbulence mixing with SCSIW. This modified KIW is then transported to the east of Taiwan. When the Kuroshio is shallow, i.e., small KLT o , the KIW transport east of Luzon is nil or southward. East of Taiwan, NPIW feeds in below the Kuroshio and is transported northward beyond the I‐Lan Ridge.