Subtropical Mode Water in a recent persisting Kuroshio large-meander period: part I—formation and advection over the entire distribution region

• DOI: 10.1007/s10872-021-00608-3
• Publication Date: 2021-06-06T14:02:52Z
• Authors: Eitarou Oka; Hatsumi Nishikawa; Shusaku Sugimoto; Bo Qiu; Niklas Schneider
• Keywords: Mode water; Argo; Meander (mathematics)

Abstract Since August 2017, the Kuroshio has taken a large-meander (LM) path, which forced extension (KE) to be in its stable state against wind-forced decadal variability. How such current conditions have impacted formation and advection of North Pacific subtropical mode water (STMW) over distribution region was examined using Argo float data during 2005–2020. Out whole STMW defined as low-potential vorticity layer 16–19.5 ºC, relatively cold variety 16–18 formed south KE advected westward southward, occupied more than 80% total volume. The rate ºC low 2006–2009 an unstable-KE period high 2010–2015 stable-KE period, then dropped drastically 2016 despite still being state. After short 2016–2017, LM-forced, began, but not restored, possibly due stronger background stratification propagated from central Pacific. In addition, had make southern detour around LM, Japan been significantly decreased, because it is dissipated strongly part Izu–Ogasawara Ridge. Due decline advection, volume hence that gradually decreased since 2016.