1. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 ADVEX, the CarboEurope-IP advection campaigns: Overview of the experimental activities at the CE sites in Renon (Italy, 2005), Wetzstein (Germany, 2006) and Norunda (Sweden, 2006) C. Feigenwinter 1,7, M. Yernaux 1, C. Bernhofer 2, U. Eichelmann 2, R. Queck 2, O. Kolle 3, M. Hertel 3, A. Lindroth 4, M. Mölder 4, L. Montagnani 5, S. Minerbi 5, D. Janous 6, M. Aubinet 1 1 Gembloux Agricultural University, Physique des Bio-systèmes, Gembloux, Belgium (FUSAGx) 2 TU Dresden, Institute of Hydrology and Meteorology, Department of Meteorology, Dresden, Germany (TUD) 3 Max Planck Institute for Biogeochemistry, Jena, Germany (MPI-BGC) 4 University of Lund, Physical Geography and Ecosystems Analysis, Lund, Sweden (LUND) 5 Autonomous Province of Bolzano, Forest Service, Agency of Environment, Bolzano, Italy (APB) 6 Institute of System Biology and Ecology, Laboratory of Plants Ecological Physiology, Brno, Czech Republic (ILE) 7 University of Basel, Institute of Meteorology, Climatology and Remote Sensing, Basel, Switzerland (MCR)

2. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 ADVEX, the CarboEurope-IP advection campaigns: Overview of the experimental activities at the CE sites in Renon (Italy, 2005), Wetzstein (Germany, 2006) and Norunda (Sweden, 2006)  ADVEX organization - aims - organization - sites and general experimental setup - short recapitulation of theory and method  Results - vertical advection - horizontal advection - selected periods  Discussion and ADVEX future

3. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 The problems that challenge night eddy covariance measurements (e.g. Massman and Lee, 2002, M. Aubinet’s talk in this session) The size of the problem - high frequency motions / small scale turbulence not captured - stationarity criteria not fulfilled / similarity relations not valid - footprint problems - failure of EC method under low turbulence conditions - reference measurement level decoupled from surface processes - horizontal transports ignored - non turbulent (low frequency) fluxes not captured (averaging interval, advection, storage) ADVEX research fields

4. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 ADVEX organization Main goals of the ADVEX project - to improve experimental measurements and setup for advection experiments - to understand the micrometeorological processes that cause the advective fluxes (katabatic (drainage) flows, stable nights, low turbulence, source strength heterogeneities, mesoscale motions, etc.) - to evaluate different methods and to find the best solution for estimating the components of the advective fluxes (e.g. vertical wind components, horizontal and vertical integration of [CO 2 ] profiles and wind profiles, uncertainty analysis, etc.) - to provide (if possible!) a methodology for the Fluxnet community to correct EC-measurements for advective influences advection = f(u*, stability, storage, EC flux, …) ????

5. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 ADVEX organization ADVEX coordination FUSAGx, Gembloux, Belgium ADVEX teams FUSAGx, Gembloux, Belgium MPI-BGC, Jena, Germany TUD, Dresden, Germany APB, Bolzano, Italy LUND, Lund, Sweden ILE, Brno, Czech Republic ADVEX sites/campaigns (Tharandt, Germany, 2001/03) (Vielsalm, Belgium, 2002/03) Renon/Ritten, Italian Alps, 2005 (120 days) Wetzstein, Thuringia, Germany, 2006 (68 days) Norunda, Uppland, Sweden, 2006 (70 days) ADVEX “philosophy“ Independent teams provide towers and material for the campaigns, which are organised by ADVEX coordination Scientific work is coordinated by ADVEX coordination, but data is in principle open to the whole CarboEurope community

6. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 ADVEX organization ADVEX sites Renon/Ritten, Italian Alps, the slope site 1730 m a.s.l., 46°35 N, 11°43 E, 85 % Norway spruce, alpine, slope 10 - 12°, canopy height 29 m, LAI 5.5, mean temp. 4.1°, mean annual precipitaton 1010 mm 500 m 0 m Renon/ Ritten Slope

7. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 CE-IP ADVEX organization ADVEX sites Wetzstein, Thuringia, Germany, the hill site 780 m a.s.l., 50°27 N, 11°27 E, Norway spruce, canopy height 20 m, LAI 4-5, mean temp. 5.9°, mean annual precipitation 840 mm 500 m0 m Tower C MPI-BGC Tower D FUSAGx Tower B LUND TowerA TUD Main Tower M MPI-BGC Wetzstein Hill

8. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 CE-IP ADVEX organization ADVEX sites Norunda, Uppland, Sweden 45 m a.s.l., 60°5’ N, 17°28’ E, pine/spruce, canopy height 25 m, LAI 4.5, mean temp. 5.5°, mean annual precipitation 527 mm 500 m 0 m Tower C MPI-BGC Tower D FUSAGx Tower B LUND TowerA TUD Central Tower M LUND Norunda Flat

9. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 CE-IP ADVEX organization ADVEX experimental setup: main characteristics CO 2 sampling: every 2.7 minutes, horizontal gradients measured by the same IRGA IRGAs: 3 LiCor 6262(7000), two pump system Sonics: 16 R.M. Young, 4/5 Gill R3, Gill HS, METEK USA-1 Measurement levels: 1.5 m, 6 m, 12 m, 30 m (1.5 m, 4.4 m, 8.8 m, 24 m at Wetzstein) Data acquisition: 1 single PC manages up to 36 COM-ports simultaneously, stores all raw data Data amount: 300 MB per day

10. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 I source/sink of c II storage change III turbulent flux (EUROFLUX, Aubinet et al., 2000; FLUXNET, Agr. For. Met. Vol. 113, 2002) IV vertical advection (Lee, 1998; Finnigan, 1999; Baldocchi, 2000; Paw U, 2000) V horizontal advection (Aubinet et al., 2003; Staebler and Fitz- jarrald, 2004; Feigenwinter et al., 2004; Marcolla et al., 2005) Theory and methodology Recapitulation of theory and methods ADVEX methodology

11. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 From measurements to advective fluxes (refer also to our poster) ADVEX methodology Step 1 Vertical extension of the 4 level measurements by fitting or linear interpolation  vertical profiles of wind velocity and [CO 2 ] for each tower Step 4 Vertical integration of calculated advection for each grid point and averaging of calculated fluxes of all grid points  Mean horizontal advection for the control volume under consideration Step 3 Introduction of a 10 m x 10 m grid and bilinear horizontal interpolation (triangulation) of [CO 2 ] profiles and horizontal wind component u(z) and v(z) for each layer dz  Horizontal advection for each layer and each grid point Step 2 Estimation of the mean vertical wind componenent by sectorwise planar fit method (Wilczak et al., 2001)  Vertical advection (Lee, 1998)

12. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 Mean diurnal [CO 2 ]and wind conditions at the slope site Renon/Ritten ADVEX results Colors: differences in [CO 2 ] concentrations at level 1.5 m 0 ppm........................+13 ppm Arrows: Wind velocity at levels: 30 m  12 m  6 m  1.5 m 

13. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 Renon/Ritten Slope range: 13 ppm Wetzstein Hill range: 6.5 ppm Norunda Flat range: 32.5 ppm selected momentary spots ADVEX results nightsituationday

14. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 Vertical advection: components and flux at ADVEX sites ADVEX results Renon/Ritten Slope Wetzstein Hill Norunda Flat Mean vertical wind component in m s -1 [CO 2 ] difference between reference level and the mean [CO 2 ] in the volume below in ppm Mean vertical advection in  mol m -2 s -1

15. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 Horizontal advection: mean diurnal course of flux at ADVEX sites ADVEX results Renon/Ritten Slope Wetzstein Hill Norunda Flat Mean Median Quartile

16. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 Horizontal advective flux vs. wind direction ADVEX results Renon/Ritten Above canopy In canopy Wetzstein Above canopy In canopy Norunda Above canopy In canopy Night Day

17. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 we have: a high quality data set from the three ADVEX experiments - with different, but well defined site characteristics (slope, hill, flat) - measured with the same experimental design (geometry and instrumentation) - processed with the same methodology  best conditions for a comprehensive and sophisticated intercomparison and analysis ADVEX summary Discussion and ADVEX future

18. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 we found (until today): - advection affects different sites in different ways - advection occurs under certain local or synoptic meteorological conditions - advection has different reasons at different sites - that it is not possible to use directly measured advection values for estimations of NEE on the base of e.g. half hourly values - that it seems possible to quantify the influence of advection for certain conditions at a certain site - that it may even be possible to extend these findings to general recommendations for certain types of sites (slope, hill, flat) we did not found (until today): - an alternative for the u * -correction - the reason for the large scatter in half hourly data - a solution to include advection estimates in annual carbon balances - ……………  there’s still a lot to do…..! ADVEX summary Discussion and ADVEX future

19. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 The methodology may be refined in terms of modeling the vertical profiles of wind and [CO 2 ] from the available measurements and in terms of the spatial integration of these data (planned cooperation with modelers). No clear relationships between the horizontal advection term and other parameters could be found until now. A major subject of investigation in the near future will be to find out, under which conditions advection occurs and what are the relevant control mechanisms and steering variables. Since the last ADVEX field activities in Norunda have been finished just some weeks ago, it’s too early to present conclusions that are generally valid. After the big efforts for the investment of time, manpower and infrastructure for the field activities, scientific work with ADVEX data is now intensified. Main fixpoints for the near future: Overview paper ready for submission in spring 2007 (among other planned publications proposed during the parallel session), ADVEX workshop in LUND in spring 2007. Discussion and ADVEX future ADVEX future

20. Open Science Conference on the GHG Cycle in the Northern Hemisphere, Sissi-Lassithi, Crete, 14 -18 November 2006 Thank you for your attention