University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Boundary-Layer Measurements The Sodar, RASS, radiation and turbulence cluster Thomas Foken Department of Micrometeorology University of Bayreuth

Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Content 1.Surface fluxes and convection 2.Experimental setup 3.Accuracy of surface fluxes 4.Quality assurance and control 5.Conclusion

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Surface fluxes and convection Net radiation Sensible heat flux (thermal convection) Latent heat flux (moist convection) Soil heat flux & Soil moisture Storage Furthermore necessary: Surface layer Deardorff velocity

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Scaling of fluxes and convection Surface layer Convective layer dynamical scaling limit (5-50 m): Remark 1: Coherent structures are already generated in the surface layer. There is a connection to such structures in the boundary layer. thermal scaling Remark 2: There is no remote sensing technique available to determine these parameters.

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Example: Free convection during the SALSA experiment Hohenpeißenberg 2005 High data quality Reduced surface wind velocity (mesoscale circulation) Increase of the unstable stratification Free convection of air from the valley (Tracer: O 3 and CO 2 )

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Experimental setup Building up of at least 3 Main Sites at convection generating area’s (2 in the valley, 1 in the mountains and single measurements in between) Sodar, energy balance and turbulent flux complexes of the Research Centre Karlsruhe Sodar-RASS, energy balance and turbulent flux complexes of the University of Bayreuth Permanent stations at Hartheim and Tuttlingen of the University of Freiburg Probable: 1 complex of an international partner

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Experimental setup of the University of Bayreuth - Flux Towers - Friction velocity Sensible heat flux Latent heat flux Carbon dioxide 3 Towers 1 Modified-Bowen- Ratio System 12 m tower

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Experimental setup of the University of Bayreuth - Radiation - Global radiation Shortwave upwelling Longwave up- and downwelling Surface temperature Soil temperature and moisture 1 Complex 2 Simpler complexes

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Experimental setup of the University of Bayreuth - Sodar-Rass - Wind vector up to 2-3 km Virtual temperature up to 1 km Scintillometer (horizontally averaged friction velocity and sensible heat flux)

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 © Mauder et al. (2006) AnemometerQuality classSensible heat fluxLatent heat flux Typ A, z.B. CSAT3 1-35% or 10 W m -2 10% or 20 W m % or 20 W m -2 15% or 30 W m -2 Typ B, z.B. R % or 20 W m -2 15% or 30 W m % or 30 W m -2 20% or 40 W m -2 Accuracy of turbulent fluxes Eddy-covariance measurements according to recent findings (EBEX-2000 in USA and LITFASS-2003 in Germany)

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 TypeSensorAccuracy in % Accuracy in W m -2 Short waveEppley PSP2 Kipp&Zonen CM11, CM 21 1 Long waveEppley PIR5 Net radiationKipp&Zonen CNR1 20 REBS Q*7(20) Schulze-Däke10 © Kohsiek et al. (2006) Accuracy of turbulent fluxes Radiation measurements according to the BSRN standard Simple system

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Quality Assurance and control Internal boundary layers Simple Footprint Quality test according to Foken & Wichura (1996)

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Further data analysis (not within the funding period) Ogive test for longwave contributions of the fluxes (approx. 2-5 % increase of the turbulent fluxes) Contributions of Turbulent organized Structures and secondary circulations to the turbulent fluxes (approx. 20 % increase of the turbulent fluxes) – Energy balance closure problem Footprint analysis for each measuring seria Uniform data analysis for all measuring sites (comparability of the sites)

University of Bayreuth Department of Micrometeorology Thomas Foken 3 rd COPS and GOP Workshop, Hohenheim, April 2006 Conclusions The measurement of the surface energy parameters is an important part to understand the generation of convection and to generate initialization parameters for models. At the present time such measurements and calculation should be done according to the standards of recent experiments and programs. The data calculation and quality control incl. footprint analysis should be done according to the recent findings (by each group or central).