Interannual variability of Kuroshio nitrate flux and transport along western boundary in the North Pacific

Yoshikazu SASAI; Hideharu SASAKI; Masami NONAKA

Presentation information

International Session (Oral)

Symbol A (Atmospheric, Ocean, and Environmental Sciences) » A-CG Complex & General

[A-CG05_30AM1] Continental-Oceanic Mutual Interaction: Global-scale Material Circulation through River Runoff

Wed. Apr 30, 2014 9:00 AM - 10:45 AM 211 (2F)

Convener:*Yosuke Yamashiki(Global Water Resources Assessment Laboratory - Yamashiki Lab. Graduate School of Advanced Integrated Studies in Human Survivability Kyoto University), Swadhin Behera(Climate Variation Predictability and Applicability Research Program Research Institute for Global Change/JAMSTEC, 3173-25 Showa-machi, Yokohama 236-0001), Yukio Masumoto(Japan Agency for Marine-Earth Science and Technology), Yasumasa Miyazawa(Japan Agency for Marine-Earth Science and Technology), Toshio Yamagata(Japan Agency for Marine-Earth Science and Technology), Kaoru Takara(Disaster Prevention Research Institute, Kyoto University), Chair:Yukio Masumoto(Japan Agency for Marine-Earth Science and Technology), Swadhin Behera(Climate Variation Predictability and Applicability Research Program Research Institute for Global Change/JAMSTEC, 3173-25 Showa-machi, Yokohama 236-0001), Toshio Yamagata(Japan Agency for Marine-Earth Science and Technology)

10:20 AM - 10:35 AM

[ACG05-06] Interannual variability of Kuroshio nitrate flux and transport along western boundary in the North Pacific

*Yoshikazu SASAI¹, Hideharu SASAKI¹, Masami NONAKA¹ (1.JAMSTEC)

Keywords:Nitrate transport, Kuroshio, Interannul variability, High-resolution ocean physical-biological model

An eddy-resolving coupled physical-biological ocean model has been employed to examine the interannual variability of nitrate flux and transport mechanism by the Kuroshio during 1995-2012. The Kuroshio provides an advective flux of nitrate carried in subsurface waters, redistributing nitrate from the tropics to the mid-latitude. Some observed data capture the nitrate flux and transport in the subsurface layers by the Kuroshio. The maximum nitrate flux core appears about 400 m depth in the East China Sea, and the nitrate transport by the Kuroshio had a mean of 170 kmol s-1. The model reproduces the maximum nitrate flux core in the subsurface layer from the Luzon strait to the Kuroshio Extension with the downstream. Along the vertical section of east side of Taiwan (24N), west side of Okinawa (28N), south of Kagoshima (130E), the time series of nitrate flux, volume transport, and nitrate concentration show the interannual variation. The variability of nitrate flux is strongly correlated with the variability of Kuroshio volume transport, but the nitrate concentration shows the increasing trend between 1995 and 2008. This trend may be related to the variability of nitrate concentration in the upstream of Kuroshio.