Theme 2: Regional Ocean Influences  Western boundary currents  Marginal seas and exchanges with open ocean  Atmosphere/Ocean interaction: impact on local and far field climate  Equatorial connection between Pacific and Indian Oceans  The WEP is the “hatchery” for ENSO  Scale interactions  Representation of regional processes in global models

Sea of Okhotsk Yaremchuk, Mitsudera (Hokkaido), South China Sea and Throughflow Qu, Yaremchuk, Yu Exchange through Luzon Strait Yarumchuk, Qu, Yu SE Indian Ocean heat budget and mixed layer Qu, Masumoto(UT), Sasaki (ES) Outflow of ITF Yu, Potemra ITF and its relation to variability of Indian and Pacific Oceans McCreary, Potemra and Schneider Western equatorial Pacific and LLWBCs Richards, Qu, Natarov, Kashino (J), Sasaki (ES) Regional studies Indian Ocean: Tracer transport, freshwater constraints, O 2 min Jensen, Yaremchuk, Yu, Aiki, et al Banda Sea Kida

LCS: Δd, n = 1 mode Circulation induced by throughflow McCreary, Miyama (FRCGC), et al

Circulation induced by throughflow There is a westward and equatorward surface (eastward and poleward subsurface) geostrophic flow across PO interior There is anomalous upwelling caused by the ITF in the Pacific wherever Δd is negative. The general structure of circulation, upwelling and downwelling is a robust feature, but details of are strongly dependent on the imposed mixing. McCreary, Miyama (FRCGC), et al Details of the exchange (pathways, vertical structure, mixing) depend on geometry and wind forcing.

Water entering the South China Sea through Luzon Strait is lower in temperature and higher in salinity (blue) than water leaving it through Karimata, Mindoro, and Taiwan Strait (red). South China Sea throughflow and its impact on the Indonesian throughflow 1. The SCSTF is a heat and freshwater conveyor, transferring up to PW of heat and 0.1 Sv of freshwater from the SCS into the tropical Indo-Pacific Ocean. 2. The SCSTF impacts the SCS heat content. In response, the SCS acts as a heat capacitor, storing heat in certain years and releasing it in others. 3. The SCSTF impacts the Indonesian throughflow. In response, the ITF heat transport is significantly (by up to 47%) reduced. Thus, the SCS is likely to play an active role in climate variability.

1/60 deg. topography (GEBCO)1/10 deg. OfES model topography Retrieving the South China Sea throughflow from T/S climatologies NPTW maximum OfES 0.1deg model WOA climatology Karimata transport: times less than diagnosed by direct simulations Topography in Karimata St. T/S in South China Sea

October 1999October 2002 NECC Analysis of OFES Varying currents in the Western Equatorial Pacific Eq 10 N

Zonal current along 138 E Sep 2001 June 2004 OFES Obs (Kashino) Eq10N

El Niño La Niña CCSMOFES

Lateral mixing: interleaving USalinity V Tracer Model Kashino Natarov and Richards (2007)

 Use of regional models to study ocean/atmosphere couplings  Analysis of OFES, CFES, SINTEX-F experiments  Use of TAO/TRITON, Argo, Satellite data  Participation in R/V Mirai cruise to study mixing in the thermocline  Use of Earth Simulator for mixing experiments  Major field programs: NPOCE, PACWIN, SPICE Western equatorial Pacific: future activities

ENSO influence on the ITF Estimates of ITF transport (8-month running- mean filtered) are shown above in comparison to an ENSO index. The mediocre correlation between ITF transport and ENSO can be explained by variations in ITF with depth. The figure on the right is a correlation of ITF transport (from SODA) in the upper 800m and MEI, and it shows how the peak correlation is at depth; ITF variability at this depth originates in the Pacific. (Potemra and Schneider)

Initialization of regional OGCMs in open boundary domains using the 3dVAR technique Global models are needed to provide open boundary conditions for regional models, but they are not accurate enough to produce realistic solutions in every region of the World Ocean (January mean of the Kyoto University 1x1 deg. global model solution, upper left panel). As a joint progect between IPRC, Hokudai University, and Kyoto Univeristy, we develop a technique for diagnostic analysis of regional circulations, which is based on the climatolgical data (temperature, salinity, ocean-atmosphere fluxes) and 3d variational method, that constrains the interpolated velocity field to be hydrostatically and geostrophically balanced and satisfy the continuity equation. Middle panel shows an example of such analysis of the January ¼ deg World Ocean Atlas (2001) climatology). In the upper left panel the analysis is applied to the regional model of the Sea of Okhotsk. The algorithm provides geostrophically balanced conditions at the open boundaries, minimizes generation of the gravity waves inside the domain and tends to keep the solution close to climatological data. We expect the technique ca be also useful for initialization of the 4dVar data assimilation schemes. (M.Yaremchuk (IPRC), H. Mitsudera, T. Nakamura, K. Uchimoto (ILTP, Hokudai), Y. Ishikawa, T. Awaji (Kyoto University, Frontier System of Global Change)

3yr average near surface currents from 1/10 degree POP NEC NECC SEC SECC NGCC MC SEC

SPICE

Marine Ecosystem Chlorophyll (phytoplankton) Krill Tuna

IPRC Activities on the Marine Ecosystem Impact of stirring and mixing (Richards) Biofeedback on SST (Timmermann) SSTΔSST caused by bio Phytoplankton 2oC2oC

 Use of regional models (e.g. iROAM) with imbedded ecosystem model  Biofeedbacks  Eastern Tropical Pacific  Arabian Sea oxygen minimum zone Future ecosystem modeling work