Argo’s Role in Climate Science First Argo Science Workshop Yakult Hall, Tokyo, Japan November 12-14, 2003 Argo’s Role in Climate Science Kimio Hanawa Department of Geophysics, Tohoku University Climate Science and Physical Oceanography cannot advance in the future without the Argo observation system!

Climate Science and Physical Oceanography (Earth Science) : “dispersive big science” ⇔ “concentrative big science” We have to measure, observe and monitor the whole of the Earth: here and there, everywhere for a long time, from the past to the future Internationally coordinated project to monitor the whole of the world’s oceans should be established: Argo project !

After AIC

Obs. locations October 2000 No.= 3755/month Locations of Argo floats (virtual) No.= 10000/month

Outcome of Argo project? Revolution in Physical Oceanography Scientific impact: Argo data will be used in various ways, and in the various fields. : mixed layer distribution, heat and freshwater storage, water mass formation, the movement, mixing and dissipation of mode waters and intermediate waters, the subduction process …… Actual achievements in Physical Oceanography using the Argo data will be well beyond our present scope.

Qualitative description => Quantitative diagnosis Revolution in Physical Oceanography Dynamical diagnosis Assimilated datasets: “Reanalysis” data => eddy-eddy interaction, eddy-mean flow interaction, vorticity dissipation, meander of the currents, formation of undercurrent … … Qualitative description => Quantitative diagnosis based on “reanalysis” data

Argo and Climate Science Decadal to centennial climate variations: CLIVAR-DecCen Manifestation of a large scale air-sea interaction. The ocean plays a crucial role at these time scales. Examples: 1. Tracing of anomalous water (subduction process) 2. Closure problem of heat and freshwater budgets

Tracing of anomalous water 0π Tracing of anomalous water Figure: 1st C-EOF mode of upper ocean heat content anomaly, one cycle ~ 40 years 1/3π Clockwise circulation of anomalous water => subduction process 2/3π π

NCEP Closure of heat budget (Freshwater budget) SOC Annual mean surface heat flux NCEP Closure of heat budget (Freshwater budget) Components: 1. Advection of heat, 2. Surface flux, 3. Temporal change rate of heat storage PX-40 PX-37 PX-44 PX-10 SOC Argo data can provide information of temporal change rates of heat and freshwater storage.

Impact on society and benefit to society Argo system is a core of WOW (World Ocean Watch)!  WWW (World Weather Watch) in the meteorological field 1. Ocean weather map 2. Prediction of the future ocean state 3. Improvement of prediction ability of long-term weather forecast

Weak points of Argo observation system To complement and overcome shortcomings and weak points, we have to adopt other observation techniques, platforms, tools, and systems! Areas in strong currents (western boundary currents), fronts, , , Stain of salinity sensor (measurement accuracy), , , Uncontrollable positioning, , ,

Thank you for your kind attention ! We hope that, more and more, new countries and new people will get aboard the Argo ship. The present Argonauts will give all newcomers a warm welcome! Thank you for your kind attention !