Intercomparison of Mesoscale and Global Atmospheric Transport Models over Western Europe P. Ciais2), A.T. Vermeulen1), C. Geels3), P. Peylin2), M. Gloor4), P. Bousquet2), T. Aalto, J. Brandt3), J. H. Christensen3), R. Dargaville, L. M. Frohn3), M. I. Gusti2), M. Heimann4), S. Houweling4), U. Karstens5), S. Körner4), I. Levin6), V. Montandon2), M. Ramonet2), C. Rödenbeck4) and M. Schmidt2). 1)Energieonderzoek Centrum Nederland (ECN), Westerduinweg 3, P. O. Box 1, 1755 ZG Petten, The Netherlands. 2)CNRS-LSCE, LSCE, Centre d’études l’Orme des Merisiers, Bât. 709, Gif-sur-Yvette Cedex, France. 3)National Environmental Research Institute, Department of Atmospheric Environment, Frederiksborgvej 399, P. O. Box 358, 4000 Roskilde, Denmark. 4)Max-Planck-Institut für Biogeochemie, Postfach , Jena, Germany. 5)Max-Planck-Institut für Meteorologie, Bundesstr. 55, Hamburg, Germany. 6)Universität Heidelberg, Heidelberg, Germany

 Evaluate ATMs for their ability to simulate synoptic variability (see regional inversions)  Compare ATMs for diurnal rectification  Compare global (coarse res) and mesoscale (fine res) models  Evaluate ATMs to simulate mean gradients  The tracers triad : 222Rn : “known “ source ; “known “ patterns FF-CO2 (14CO2 ) : known source ; uncertain patterns CO2 : unknown source ; unknown patterns Objectives

Summary of grid set up in the models

Summary of meteorology and physics

Station locations Red = CO 2 Yellow = CO 2 in situ Green = 222Rn in situ Blue = 14C Black = eddy flux towers (not used)

Period July 1998 ; December 1996 Winds ECMWF 6-hourly 222Rn Constant emission over non-iced lands 1 atom cm-2 sec-1 CO2 Air sea fluxes from takahashi, 1999 Air-land fluxes from LUE model TURCB Fossil fuel emissions from Andres et al. Atm. boundary conditions from C TM3FG (X,t) Diagnostics Monthly mean patterns (daytime ; full time) Monthly mean gradients among stations Time series at stations Average diurnal cycle at stations Intercomparison set-up

[ gC / m 2 / jour ] Bayreuth [ gC / m 2 / jour ] Tharandt AvrilMaiJuinJuilletAoûtSept.Oct. Mars Eddy data TURCB semaines [ gC/m 2 /jour ] Remarks on prescribed air-land fluxes Include diurnal cycle of NEE ; Agreement with eddy flux data EuropeN. Asia Seasonal cycle too strong & too early in Europe ; No missing sink to close the N.H. budget (see Rivier’s talk) Inversion TURCB

Dec.Jul. Mapping the 222Rn signal

Dec. Jul. Mapping the 222Rn signal

Longitudinal Stations Transect at 45-60°N July 1998 (FF from radiocarbon data Levin et al.)

Coastal Surface Mountain 1205 m 222Rn time series JULY

Coastal baseline Surface Germany Surface Russia 222Rn time series DECEMBER

Mountain Germany 1205m Tower hungary 115m High Alt. italy 3405m CO2 time series

 Large differences in vertical mixing; with global models LMDZ, TM3FG tending to mix more strongly  Inter model differences not similar in Jul vs. Dec  All models capture the longitudinal mean gradient in 222Rn and FF-CO2 ; differ for diurnal rectification of bio-CO2  Mesoscale models (generally) better capture the diurnal cycles  All models capture correct the timing of synoptic variability ; differ in the amplitude of the synoptic events  Continuous 222Rn, 14CO2, CO2 records have complementary usefulness  Data selection of in-situ records to be improved Preliminary conclusions

LMDZ REMO-D TM3-FG HANKDEHM Overall strength of vertical mixing over continent Fossil CO2 ; 222Rn continentality gradient at stations Variability and correlation with obs.time series 222Rn ; JUL Variability and correlation with obs.time series 222Rn ; DEC In short …. weak strong Too high Ok Too small Too large

Slides for questions