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Thomas Foken, Mathias Göckede, Matthias Mauder Department of Micrometeorology

Results of footprint based quality assessment and quality control study for forest sites. Thomas Foken, Mathias Göckede, Matthias Mauder Department of Micrometeorology University of Bayreuth, Germany with contributions by Tiina Markkanen University of Helsinki.

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Thomas Foken, Mathias Göckede, Matthias Mauder Department of Micrometeorology

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  1. Results of footprint based quality assessment and quality control study for forest sites Thomas Foken, Mathias Göckede, Matthias Mauder Department of Micrometeorology University of Bayreuth, Germany with contributions by Tiina Markkanen University of Helsinki

  2. QA/QC: Evaluation of measurement sites - Concept - • Combination of QA/QC tools for eddy covariance measurements with footprint analyses • Quality assessment: Assignment of QC-flags for individual flux measurements according to Foken & Wichura (1996) and Foken et al. (2004) • - Footprint-Analysis: Calculation of source areas (model by Rannik et al., 2003) to determine the spatial context of a measurement

  3. QA/QC: Evaluation of measurement sites - Objectives - • Link between data quality and the characteristics of the surrounding terrain • Determination of a footprint climatology for a longer measurement period • Analysis of the flux contributions emitted from different types of land use to the total flux measured • Special effects, like influences of the sensor on the measurements

  4. QA/QC: Evaluation of measurement sites - Working programme - • Sites with measurements above high vegetation • 23 sites were analyzed and 2 associated sites • no information available from 5 sites (FR-Fon, SE-Nor, SE-Sky1, SE-Sky2, UK-PLa3) • Sites with measurements above low vegetation • no analysis of meteorological measurements- fetch analysis, flux contribution from target land use • not reported in this paper

  5. Influences of the sensor set up METEK USA-1; Use of the head correction • FI-Sod • Data quality of latent heat flux • Fr-Pue • vertical wind velocity after planar-fit

  6. Influences of the sensor set up Mounting of the sonic anemometer on the tower • DE-Wet • Boom on the tower, data quality of momentum flux • Similar results for NL-Loo

  7. Footprint analysis of fluxes emitted from the target area Chose a threshold of 80% of flux emitted by the target land cover 1. 90% or more of data exceed 80%-threshold: 13 sites 2. 60% to 90% of data exceed 80% threshold: 4 sites 3. 50% to 60% of data exceed the 80% threshold: 3 sites 4. Less than 50% of data exceed the 80% threshold: 4 sites • ● Source-area analysis • Basic idea: In complex terrain, the changing source-area under different meteorological conditions affects the flux data quality according to several aspects. Use of the footprint analyses by Rannik et al. (2003): • Chose a threshold of 80% of flux emitted by the target land cover: • 90% or more of data exceed 80%-threshold: 13 sites • 60% to 90% of data exceed 80% threshold: 4 sites • 50% to 60% of data exceed the 80% threshold: 3 sites • Less than 50% of data exceed the 80% threshold: 4 sites Chose a threshold of 80% of flux emitted by the target land cover: 90% or more of data exceed 80%-threshold: 13 sites 60% to 90% of data exceed 80% threshold: 4 sites 50% to 60% of data exceed the 80% threshold: 3 sites Less than 50% of data exceed the 80% threshold: 4 sites

  8. Category 4: Fr-Pue, BE-Bra, DK-Sor, PT-Mit1 • DK-Sor

  9. Category 4: Fr-Pue, BE-Bra, DK-Sor, PT-Mit1 • PT-Mit1

  10. Flux data quality assessment • ● Source-area analysis • Basic idea: In complex terrain, the changing source-area under different meteorological conditions affects the flux data quality according to several aspects. Use of the footprint analyses by Rannik et al. (2003): • Chose a threshold of 80% of flux emitted by the target land cover: • 90% or more of data exceed 80%-threshold: 13 sites • 60% to 90% of data exceed 80% threshold: 4 sites • 50% to 60% of data exceed the 80% threshold: 3 sites • Less than 50% of data exceed the 80% threshold: 4 sites Chose a threshold of 80% of flux emitted by the target land cover: 90% or more of data exceed 80%-threshold: 13 sites 60% to 90% of data exceed 80% threshold: 4 sites 50% to 60% of data exceed the 80% threshold: 3 sites Less than 50% of data exceed the 80% threshold: 4 sites

  11. Flux data quality assessment 1. Highest quality – no disturbances: 6 sites 2. Only disturbances in isolated wind sectors: 7 sites 3. Isolated disturbances and up to one omnidirectional effect: 7 sites 4. Multiple omnidirectional effects: 5 sites • ● Source-area analysis • Basic idea: In complex terrain, the changing source-area under different meteorological conditions affects the flux data quality according to several aspects. Use of the footprint analyses by Rannik et al. (2003): • Chose a threshold of 80% of flux emitted by the target land cover: • 90% or more of data exceed 80%-threshold: 13 sites • 60% to 90% of data exceed 80% threshold: 4 sites • 50% to 60% of data exceed the 80% threshold: 3 sites • Less than 50% of data exceed the 80% threshold: 4 sites Chose a threshold of 80% of flux emitted by the target land cover: 90% or more of data exceed 80%-threshold: 13 sites 60% to 90% of data exceed 80% threshold: 4 sites 50% to 60% of data exceed the 80% threshold: 3 sites Less than 50% of data exceed the 80% threshold: 4 sites

  12. Category 4: CH-Lae, ES-LMa, FI-Hyy, Fr-Pue, It-Col • FI-Hyy: • CO2-flux • ● Source-area analysis • Basic idea: In complex terrain, the changing source-area under different meteorological conditions affects the flux data quality according to several aspects. Use of the footprint analyses by Rannik et al. (2003): • Chose a threshold of 80% of flux emitted by the target land cover: • 90% or more of data exceed 80%-threshold: 13 sites • 60% to 90% of data exceed 80% threshold: 4 sites • 50% to 60% of data exceed the 80% threshold: 3 sites • Less than 50% of data exceed the 80% threshold: 4 sites Chose a threshold of 80% of flux emitted by the target land cover: 90% or more of data exceed 80%-threshold: 13 sites 60% to 90% of data exceed 80% threshold: 4 sites 50% to 60% of data exceed the 80% threshold: 3 sites Less than 50% of data exceed the 80% threshold: 4 sites

  13. Most of the stations: Slightly worse quality during unstable stratification coursed by convection and coherent structures • DE-Wei: • momentum-flux

  14. Overview (all stations) • ● Source-area analysis • Basic idea: In complex terrain, the changing source-area under different meteorological conditions affects the flux data quality according to several aspects. Use of the footprint analyses by Rannik et al. (2003): • Chose a threshold of 80% of flux emitted by the target land cover: • 90% or more of data exceed 80%-threshold: 13 sites • 60% to 90% of data exceed 80% threshold: 4 sites • 50% to 60% of data exceed the 80% threshold: 3 sites • Less than 50% of data exceed the 80% threshold: 4 sites Chose a threshold of 80% of flux emitted by the target land cover: 90% or more of data exceed 80%-threshold: 13 sites 60% to 90% of data exceed 80% threshold: 4 sites 50% to 60% of data exceed the 80% threshold: 3 sites Less than 50% of data exceed the 80% threshold: 4 sites

  15. Overview (all stations) • ● Source-area analysis • Basic idea: In complex terrain, the changing source-area under different meteorological conditions affects the flux data quality according to several aspects. Use of the footprint analyses by Rannik et al. (2003): • Chose a threshold of 80% of flux emitted by the target land cover: • 90% or more of data exceed 80%-threshold: 13 sites • 60% to 90% of data exceed 80% threshold: 4 sites • 50% to 60% of data exceed the 80% threshold: 3 sites • Less than 50% of data exceed the 80% threshold: 4 sites Chose a threshold of 80% of flux emitted by the target land cover: 90% or more of data exceed 80%-threshold: 13 sites 60% to 90% of data exceed 80% threshold: 4 sites 50% to 60% of data exceed the 80% threshold: 3 sites Less than 50% of data exceed the 80% threshold: 4 sites

  16. Conclusions • The footprint and data quality analysis can only be one criteria for site evaluation. • Is the ecosystem or the latitude or altitude of the station important for the aims of CARBOEUROPE ? • Is the special character of an ecosystem (boreal, alpine) a reason for a lower data quality ? • Is the station equipped also with other measuring systems that this station can be used for further research ? • Is the staff of the station able to handle even complicate situations and make footprint and data quality analysis before submitting the data to the data basis ? • ● Source-area analysis • Basic idea: In complex terrain, the changing source-area under different meteorological conditions affects the flux data quality according to several aspects. Use of the footprint analyses by Rannik et al. (2003): • Chose a threshold of 80% of flux emitted by the target land cover: • 90% or more of data exceed 80%-threshold: 13 sites • 60% to 90% of data exceed 80% threshold: 4 sites • 50% to 60% of data exceed the 80% threshold: 3 sites • Less than 50% of data exceed the 80% threshold: 4 sites Chose a threshold of 80% of flux emitted by the target land cover: 90% or more of data exceed 80%-threshold: 13 sites 60% to 90% of data exceed 80% threshold: 4 sites 50% to 60% of data exceed the 80% threshold: 3 sites Less than 50% of data exceed the 80% threshold: 4 sites

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