JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Oral

A (Atmospheric and Hydrospheric Sciences) » A-CG Complex & General

[A-CG43] [EE] Air-sea interaction in the extratropics

Sat. May 20, 2017 1:45 PM - 3:15 PM 302 (International Conference Hall 3F)

convener:Kazuaki Nishii(Graduate School of Bioresources, Mie University), Yoshi N Sasaki(Hokkaido University), Shusaku Sugimoto(Graduate School of Science, Tohoku University), Shun Ohishi(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo), Chairperson:Kazuaki Nishii(Graduate School of Bioresources, Mie University), Chairperson:Ryusuke Masunaga(Research Center for Advanced Science and Technology, The University of Tokyo)

1:45 PM - 2:00 PM

[ACG43-01] Inter-decadal modulations in the dynamic state of the Kuroshio Extension system: 1905-2016

★Invited papers

*Bo Qiu1, Shuiming Chen1, Niklas Schneider1 (1.Department of Oceanography, University of Hawaii at Manoa)

Keywords:Kuroshio Extension, decadal variability, air-sea interaction

The Kuroshio Extension is an eastward-flowing, inertial jet in the subtropical western North Pacific after the Kuroshio separates from the coast of Japan. Being the extension of a wind-driven western boundary current, the KE has long been recognized as a turbulent current system rich in large-amplitude meanders and energetic mesoscale eddies. An important feature emerging from the past 25-yr satellite altimeter measurements is that the KE system exhibits clearly-defined decadal modulations between a stable and an unstable dynamic state. The decadally-modulating KE dynamic state exerts a great impact on the regional sea surface temperature, heat content and water mass properties. By clarifying the relationship and physical processes between the basin-scale wind forcing and the KE dynamic state over the altimeter era, we hindcast the KE dynamic state going back to 1905 with the use of ECMWF reanalysis wind stress product. It is found that the low-frequency KE variability modulated in the past century in connection with the mid-1920s, mid-1940s, and mid-1970s' climatic regime shifts in the Aleutian Low pressure system. In addition to the modulations in KE's response to the external wind forcing, the midlatitude ocean's feedback to the overlying atmosphere appeared to have differed within the epochs of the different 20th century regimes.