Date: Wed, 12 Sep 2001 17:02:37 -0600 To: scw@io.harvard.edu, harriss@ucar.edu From: Jielun Sun Subject: NACP Cc: jsun@ucar.edu Steve and Bob, Sorry I could not make the NACP meeting at Boulder since I got the notice too late and I already made plan for that week. Here are my comments on the NACP draft. In general, I like the plan. It covers many aspects of the carbon study. Maybe the plan could emphasize at the beginning what is beyond the current long-term global carbon observation programs. Also I like the process studies to define key mechanisms responsible for carbon exchanges between the atmosphere, oceans, and land. It would be very helpful to identify known and potential unknown mechanisms responsible for carbon exchange, such as source/sink mechanisms and also transport mechanisms, before we head out to another field experiment. This way, we can design experimental strategies to cover potential mechanisms for the carbon exchange. By accumulating knowledges on various key mechanisms responsible for carbon exchanges from a relatively small spatial scale experiment, we would be in a better position to design or modify current long-term carbon observation programs. I am not familiar with Lagrangian models. From a micrometeorologist point of view, I would think that spatial and temporal variations of turbulent fluxes and mesoscale phenomena would add complications to the reverse method. I don't know how sensitive the reverse method is to accuracy of estimated turbulent fluxes either through models or observations. As far as I know, mesoscale meandering motions, especially at night, could dominate major transports of trace gases. Even sophisticated LES models cannot handle random, meandering mesoscale disturbances. Best regards, Jielun --------------------------------------------------- Jielun Sun NCAR/MMM P.O.BOX 3000 3450 Mitchell Lane Boulder, CO 80307-3000 USA Phone: 303-497-8994 (office) FAX: 303-497-8171 jsun@ucar.edu