From dia@ecmwf.int Tue Sep 4 06:35:55 2001 Alan Betts Dear Alan, (cc S.Wofsy, R.Harriss, M.Gloor, D.Schimel) Thanks for sight of the draft NACP. After a fast read (in view of tomorrow's NCAR workshop), I have three fast comments: LAND The COCO project will address first the estimation of total column CO2 over ocean, as there is a good understanding of the ocean surface emissivity both in the IR and in the MW. Extension of the COCO approach to the land will require, for the 15 micron CO2 band and the MW, a much improved understanding of varitions in land surface emissivity at the AIRS and AMSU pixel scales (12-40km). The NACP may wish to note the gap, and propose actions to plug the gap. There may be fewer land surface emissivity problems with the 4.3 micron CO2 band, but solar effects will limit use of that band to night-time conditions. OCEAN The NACP makes one reference (on page 19) to the value of ocean colour measurements in deriving an estimate of atmosphere-ocean CO2 exchange. In 2002 there will be 5 ocean colour instruments in orbit: SeaWIFS, MODIS-Terra, MODIS-Aqua, MERIS-ENVISAT, OCTS-ADEOS/II, [ +2xAVHRR!]. Assimilation of ocean-colour data in an ocean circulation model furnished with a carbon cycle would provide a totally new estimate of ocean uptake, independent of COCO-style use of atmospheric satellite measurements. NACP may wish to acknowledge and plug the gap, and to exploit the synergy. REANALYSIS: The NACP makes repeated reference to a requirement for a long record of 3-D fields of parametrized tendencies (including mass fluxes) from reanalyses. ECMWF's ERA-40 reanalysis project meets the requirements with 6-hourly fields of 3-D physical tendencies (horizontal resolution 125km, 60 levels in the vertical between the surface and 65km). The archived fields were selected with help from the European atmospheric chemistry community and include: updraught & downdraft mass fluxes, updraft & downdraft entrainment rates, Long wave & shortwave radiative heating, clear-sky long wave & short wave, net u-momentum tendency, net v-momentum tendency, net temperaturetendency net humidity tendency (all averaged over 3 or 6 hours) The documentation of the relevant products (v. section 3.7 of the documentation) can be down loaded from http://wms.ecmwf.int/research/era/Products.html. Fives years of ERA-40 production are being validated at present (1987-1991). Production of the period 1958-2001 should be completed by the end of 2002. Tony -- ============================================ Tony Hollingsworth /ph +44 118 949 9005 (direct line) Head of Research / +44 118 949 9000 (switchboard) ECMWF /fax +44 118 986 9450 Shinfield Park, READING /e-mail: a.hollingsworth@ecmwf.int RG2 9AX, UK / http://www.ecmwf.int --- Forwarded mail from Steven_Wofsy@harvard.edu Date: Tue, 4 Sep 2001 09:12:26 -0400 (EDT) From: Steve Wofsy To: dia@ecmwf.int (Tony Hollingsworth) Subject: Re: NA Carbon plan Reply-To: Steven_Wofsy@harvard.edu Thanks very much for these helpful comments. I have not studied in detail the issues for AIRS CO2 data, but I'm not surprised that the emissivity issues are limiting. I hope we can have some further discussions about the ERA-40 products. We would be very interested in applying these fields to our Lagrangian ensemble analysis of the CO2/CO flights over North America in August, 2000. The web site indicates that use is restricted to EU investigators. Would it be possible to obtain the fields for the experiment periods? (The COBRA data, and in fact all of our data on CO2 fluxes at tower sites, are freely available to everyone.) Thanks again. --s Steven C. Wofsy Abbott Lawrence Rotch Professor of Atmospheric and Environmental Chemistry Harvard University Pierce Hall, Room 110D, 29 Oxford St., Cambridge, MA 02138 email: Steven_Wofsy@harvard.edu Telephone: 617-495-4566 FAX: 617:495-4551 ====================================================================== Steve, It will be a few months yet before we produce the ERA-40 reanalyses for 2000. Peter van Velthoven of KNMI is our main interlocutor with the chemistry community Currently, access to the ERA-40 reanalyses is limited to our EU-funded validation teams, who are spinning up their validation procedures. Once they are happy with the reanalyses, the first few years of validated data will be put on general release. We hope to release validated data thereafter, year-by reanalysed year, at better than monthly intervals. Check with Roy Jenne's shop to see if NCAR will have the datasets you require. If yes you can get the data from NCAR. If not you can get them through our Data Services. Like NCAR, we levy a reasonable handling charge to cover our handling costs; there is no information charge. Data.Services@ecmwf.int can estimate the cost for your requirements. Tony