July 1,2002

We are writing to express our concerns about the current plans for the US CLIVAR program as expressed in the US CLIVAR documents, especially the US CLIVAR Implementation plan, the Pacific PBECS plan and the Pacific Implementation plan. We trust that you will pass these concerns on to the CLIVAR SSC and hopefully discuss them at the next SSC meeting.

As originally conceived in the international CLIVAR Science Plan and the Implementation Plan, written by the international CLIVAR SSG, CLIVAR would concentrate on a number of activities focused on phenomena on various time scales (G1, G2, …D1, D2,… etc) and these activities would be supported by a range of enabling and supporting activities such as reanalysis and sustained ocean observations. The ultimate success of CLIVAR would then be measured by the extent to which these various seasonal-to-interannual and decadal phenomena would be understood.

This strategy is summarized by the diagram shown below:

Looking over the US CLIVAR documents, we see much of the enabling and supporting activities in the outer ring of the implementation diagram, but little of the concentration on the phenomena of interest. The elucidation of global phenomena is the essence of CLIVAR, but I find little in the US plan that shows us the path to unraveling these global scale climate phenomena.

It seems to us that we learned three lessons from doing the TOGA program. The first was to focus on a phenomenon and do whatever it takes to elucidate that phenomenon. The second is that getting models and observations together at a very early stage of the program (even when premature) is the surest road to progress. The third is that the right combination of top down organization and bottoms up enthusiasm is needed to solve complex problems.

The present planned activities of US CLIVAR present the right mix of top down organization and largely contributes to the outer ring the diagram. We do not see, however, that doing only these outer ring activities will address the problems in the inner ring, although they clearly are needed for addressing them. We believe it is necessary to encourage scientists to form bottoms-up groups to address the phenomena in the inner circle of the diagram and to bring together the right mix of modeling, diagnostics, and analysis. If such groupings are accomplished, the job of the SSC would then be to make sure that there is continuing interaction between the enabling activities and the direct focus on climatic phenomena. The concept of process teams has been established by the SSC--we believe the similar concept of phenomena teams more directly addresses the objectives of US CLIVAR.

These phenomena teams would initially concentrate on modeling and analysis of the climate system. After an initial period, and if enough is learned, the phenomena teams would either suggest specific observations or additional coordinated modeling and analysis programs. At that point, the enabling activities would have to respond. While success is by no means guaranteed, there is at least a straighter path towards solving the underlying problems of CLIVAR. In particular, we the undersigned, on the basis of a session on Pacific Decadal Variability (PDV) that we convened at the Spring AGU, intend to pursue a program on PDV by convening a workshop of interested scientists and writing a prospectus for a focused program on PDV.

We believe that the SSC should encourage and endorse such grass roots activities and hope that the SSC will, at the next meeting, consider carefully such activities and find ways of encouraging their implementation.

Sincerely,

Nathan Mantua and Ed Sarachik

Center for Science in the Earth System

University of Washington