INTERANNUAL VARIATIONS OF NORTH PACIFIC SUBTROPICAL MODE WATER IN THE137-DEGREES-E SECTION

Examination of interannual variations of North Pacific subtropical mod e water (STMW) in the 137 degrees E repeat hydrographic section by Sug a et al. is extended to seek a relation between changes in STMW renewa l and the wintertime cooling. Time series of isopycnal potential vorti city (PV) and apparent oxygen utilization (AOU) demonstrate substantia l interannual variations of STMW. It is suggested that the interannual variations are closely related to the changes both in the Kuroshio re circulation system and in the formation rate. For the non-large-meande r period of the Kuroshio, during which renewed STMW is advected vigoro usly from east of the section, the monsoon index as an indicator of co oling in a given winter, and PV and AOU at an STMW isopycnal surface i n the following summer show significant correlation, indicating a stro ng relation between the wintertime cooling and the STMW formation.