SYNOPSIS OF THE EQUATORIAL PACIFIC SYNTHESIS AND MODELLING WORKSHOP (EPSMW) AND THE EPSMG MEETING September 17-19, 2002 Darling Marine Center, University of Maine, Walpole, Maine, USA Fei Chai School of Marine Sciences University of Maine USA - and - Robert Le Borgne IRD (ex-ORSTOM) Nouméa, New Caledonia France

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Background:

During the past three years, the JGOFS Equatorial Pacific Synthesis and Modelling Group (EPSMG) coordinated efforts to organize a special issue of Deep-Sea Research dedicated to the synthesis and modelling for the Equatorial Pacific. After the completion of this work, it was felt that the modellers could benefit from the new ideas and concepts brought about by the synthesis. Subsequently, a small workshop, gathering leaders of the synthesis topics and modellers, was organized by Fei Chai (University of Maine, member of EPSMG) and Robert Le Borgne (IRD-ex ORSTOM, chairman of EPSMG), following the decision taken by the EPSMG during its Bergen meeting in April 2000. The JGOFS SSC approved the workshop in July 2001 and supported part of the cost, together with US-JGOFS and PROOF (French component of JGOFS).

Objectives of the workshop:

1. To bring observationalists and modellers together in order to present the updated synthesis and modelling results.
2. To identify the gaps in the current models and the way they can be filled.
3. To discuss potential international collaborative research on the equatorial Pacific.

From the start, the workshop aimed at being international with a balanced number of observationalists and modellers. However, for reasons independent of financial ones, there was only one representative from Australian JGOFS, Canadian JGOFS, and Japanese JGOFS. The rest of the participants were French (4), Chinese (2) and US (16). A list of the 25 participants is given in the section of List of Participants. The meeting benefited from participation of top scientists working in various field dealing with the equatorial Pacific and/or the global oceans.

Location:

The Darling Marine Center of the University of Maine hosted the meeting in a very quiet and peaceful environment. The very helpful staff of the Center and the weather contributed to the success of the meeting.

Agenda:

The workshop was organized in half-day sessions devoted to the main topics (see EPSMW 2002 Agenda for details). The session on «large-scale description of the equatorial area from remote sensing, moorings and oceanographic cruises» had presentations on the PDO, the variations of sea surface chlorophyll during the 1997-1998 El Niño and the following La Niña, effect of Tropical Instability Waves (TIW) on the carbon cycle from models, zonal and latitudinal variabilities and the latitudinal asymmetry with respect to the equator. The session on «the biological pump and its short-term variability» considered both the warm pool and the HNLC system and provided a fair amount of knowledge on several subjects and unresolved questions, particularly where iron distribution and inputs are concerned. The following session considered «ecosystem modelling» of the HNLC system, which is still being developed and should benefit from the workshop. The session on «long-term variations of the CO2 flux and the biological pump» considered different time-scales and stressed the need for a continuation of monitoring activities in order to test and improve model predictions. «Modelling of various time scale variabilities (seasonal, ENSO and PDO)» followed and showed interesting modelling directions. Most presentations made during the workshop are available through the JGOFS IPO website, or send an email to Fei Chai (fchai@maine.edu) to request a CD-ROM which contains all the presentations as PowerPoint files.

The workshop finished with general remarks considering the following topics:

Is the equatorial Pacific different from other equatorial systems and the other regions studied in the frame of JGOFS?
How strong is the organic carbon pump in the ocean and how does the equatorial Pacific fit in?
Finally, what is the impact of diatoms in climate variability?

1. the Tropical Instability Waves have been observed during two oceanographic cruises, but we rely presently on models to assess their net impact on the carbon budget because processes take place in three dimensions (longitude, latitude and depth). Special operations, combining remote sensing, oceanographic cruises and moorings are the only way to validate the models and they require more international cooperation.
2. In a similar way, interactions between iron and silicate and their effects on primary production are currently considered in models but there is lacking of in situ observations on the iron distribution and inputs and experimental works considering the combined effects of both nutrients.
3. There is also a need to validate remote sensing measurements and model outputs on long-term variations by field observations. This requires long-term monitoring by sensors equipped on moorings (e.g., NOAA TAO project), ships of opportunities and oceanographic cruises.

Conclusions:

During the EPSMG meeting, following the workshop, its members and a few workshop participants noted several general conclusions from the workshop. Given its small size and the high level of the participants, the amount of information that came out was amazingly high. Part of the explanation comes from the fact that the Equatorial Pacific JGOFS fieldwork took place at the right time. Thus, it benefited from a good physical description after the implementation of the TAO project, new technologies that had just been developed (e.g. flow cytometry, bio-optical sensors, etc.), and the succession of various climatic events, which took place in a rather short timeframe. However, the unprecedented knowledge acquired on the entire region, which covers almost half of the earth circumference), would not have been possible without the efficient international collaboration that was organized from the start. As expected, the workshop was found useful to the modellers. The new model development and modelled results produce a new set of questions, which will deserve, benefit from novel experiments or new observations in the future. The workshop also confirmed an unexpected output from the JGOFS project, which is the use of modelling ecosystem studies by a component of GLOBEC involved in tuna fisheries occurring in the warm pool. Finally, the participants agreed with the need to continue an international program, as within the JGOFS project or any future ocean research programs, such as recently developed OCEANS program. The future resides in monitoring activities, oceanographic cruises and utilisation of sea colour from remote sensing. Overall, the workshop showed an impressive progress with respect to the JGOFS SMP meeting, which took place three years ago in Norfolk, thanks to the efforts put on synthesis, and modelling works. A possible output would be the organisation of a training course on the equatorial Pacific for graduate students and post-docs. This would constitute a good start for future studies in the region.

List of Participants:

Richard BARBER	Duke University, Beaufort, North Carolina, USA
Fei CHAI	University of Maine, Orono, Maine, USA
Richard DUGDALE	San Francisco State University, Tiburon, California, USA
John DUNNE	Princeton University, Princeton, New Jersey, USA
Andrew EDWARDS	Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada
Scott ELLIOTT	Los Alamos National Laboratory, Los Alamos, New Mexico, USA
Richard FEELY	PMEL/NOAA, Seattle, Washington, USA
Marjorie FRIEDRICHS	Old Dominion University, Norfolk, Virginia, USA
Michael LANDRY	University of Hawaii at Manoa, Honolulu, Hawaii, USA
Edward LAWS	University of Hawaii at Manoa, Honolulu, Hawaii, USA
Robert LE BORGNE	IRD (ex-ORSTOM), Nouméa, New Caledonia, France
Patrick LEHODEY	South Pacific Commission, Nouméa, New Caledonia, France
Aude LEYNAERT	Institut Européen de la Mer, Brest, France
Denis MACKEY	CSIRO Marine Research, Hobart, Tasmania, Australia
Chuck McCLAIN	NASA/GSFC, Greenbelt, Maryland, USA
Michael McPHADEN	PMEL/NOAA, Seattle, Washington, USA
Nicolas METZL	CNRS, LBCM, Université P. et M. Curie, Paris, France
David NELSON	Oregon State University, Corvallis, Oregon, USA
Michael ROMAN	University of Maryland, Cambridge, Maryland, USA
Shaoling SHANG	University of Maine, Orono, Maine, USA
Lei SHI	University of Maine, Orono, Maine, USA
Lan SMITH	Frontier Research System, Yokohama, Japan
Pete STRUTTON	SUNY, State University of New York, Stony Brook, New York, USA
Robbie TOGGWEILER	GFDL/NOAA, Princeton, New Jersey, USA
Mark WELLS	University of Maine, Orono, Maine, USA

EPSMW 2002 Agenda