August 1998

COARE revisited

Jerry Meehl (NCAR) and Steve Anderson (Woods Hole Oceanographic Institution), representing the work of seven TOGA COARE scientists, led a session on the afternoon of 10 July to identify the challenges that remain in each of COARE's goal areas. As with the other review talks at the meeting, the material they presented will be part of an upcoming article in the Bulletin of the American Meteorological Society.

Jerry led off with a recommendation that could help transfer the large body of knowledge learned during COARE to the global coupled model community. This would entail using such models to make an intercomparison of large-scale coupled processes involved with the Madden-Julian Oscillation (MJO, a regional-scale mass of tropical convection that moves through the western tropical Pacific every 30 to 60 days). According to Jerry, this work could become part of the Coupled Model Intercomparison Project, an activity he chairs as part of the Climate Variability and Predictability program (discussed below).

Steve followed with a straw-person list of several dozen challenges, including

• the role of microphysical cloud processes in tropical convection

• the importance of mesoscale convective systems (large complexes of showers and thunderstorms) in the evolution of temperature and salinity in the upper part of the tropical Pacific

• the evolution of the MJO from short-lived showers and thunderstorms into larger, more sustained events lasting weeks.

  Audience members added a number of further challenges to the list presented by Jerry and Steve. For instance:

• What factors organize convection below the MJO scale across the warm pool? "I think we've swept this under the rug," said former NCAR scientist Ed Zipser (Texas A&M University). "I don't think there's any chance of understanding this from the TOGA COARE data set [alone], but I think we have to keep trying."

• How can the diurnal cycle of heating and convection across the warm pool be accurately rendered in weather and climate models? Julia Slingo (University of Reading, England) noted that the diurnal cycle's strength and timing is still difficult to reproduce over land, much less over the ocean.

Some research threads from TOGA COARE will be woven into two upcoming projects. One is the massive Global Energy and Water Cycle Experiment (GEWEX), which is conducting a set of nine regional experiments across four continents. (Mitch is a member of the GEWEX Scientific Steering Group, or SSG.) In North America, the GEWEX Continental-Scale International Project is centered over the Mississippi River Basin.

NCAR's Kevin Trenberth updated the group on another ambitious research program, the Climate Variability and Predictability (CLIVAR) program. On 1-4 December, after several years of planning, CLIVAR will be introduced to the public as part of an international meeting of government delegations in Paris. Kevin is cochair of CLIVAR's SSG.

CLIVAR's main goal over the next five years is to advance the understanding of weather and climate variability over the time scales of years to a century. Under that umbrella will be a variety of studies of the El Niño/Southern Oscillation phenomenon, the Asian and Australian monsoons, the North Atlantic Oscillation, and climate variability in general in regions across the globe. Another CLIVAR focus is to improve the detection and attribution of climate change.

CLIVAR serves as the main vehicle for the World Climate Research Program in studying the role of the ocean in the coupled climate system and the use of coupled models for evaluating human-caused climate change. "This is a framework where a lot of COARE activities may continue to find a home," said Kevin.

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