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Scintillometer and eddy covariance comparisons over sagebrush and invasive cheatgrass communities in Idaho EPSCoR Proje

Scintillometer and eddy covariance comparisons over sagebrush and invasive cheatgrass communities in Idaho EPSCoR Project Suported by NSF. Authors. University of Idaho – Wenguang Zhao, Rick Allen, Clarence Robison, Jeppe Kjaersgaard, Ricardo Trezza, Aureo Oliveira, Ramesh Dhungel

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Scintillometer and eddy covariance comparisons over sagebrush and invasive cheatgrass communities in Idaho EPSCoR Proje

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  1. Scintillometer and eddy covariance comparisons over sagebrush and invasive cheatgrass communities in IdahoEPSCoR Project Suported by NSF

  2. Authors University of Idaho – Wenguang Zhao, Rick Allen, Clarence Robison, Jeppe Kjaersgaard, Ricardo Trezza, Aureo Oliveira, Ramesh Dhungel Idaho State University – Matt Germino Boise State University – Venkat Sridhar Wageningen University – Henk de Bruin

  3. Background 1. Sensible heat flux (H) is an important energy dissipation in surface energy balances and evapotranspiration (ET) studies. 2. Representation of H and ET measured by traditional methods (EC and BR etc) is limited, especially for heterogeneous fields. 3. Large aperture scintillometry (LAS) is an alternative method to estimate H from a relatively large footprint (source) area.

  4. Questions 1. How can we accurately calculate H from the LAS measurement, structure function constant of refractive index fluctuations for the wavelength used by the LAS? 2. How does the H calculated by the LAS measurement compare to the traditional EC measurement result?

  5. Experiment sites Mack’s Inn Site (Alpine Forest) Raft River Site (Cheatgrass) Hollister Site (Sage Brush)

  6. Instrumentation

  7. Hollister Site: Sagebrush

  8. LAS Transmitter

  9. LAS Receiver

  10. Eddy Covariance Site 1

  11. Eddy Covariance system

  12. Radiation System

  13. Soil Sensors

  14. Raft River Site: Cheatgrass

  15. LAS: Transmitter A & Receiver B

  16. Eddy Covariance Site 1

  17. Mack’s Inn Site: Alpine forest (south tower)

  18. Mack’s Inn Site: Alpine forest (north tower)

  19. Results and Discussions

  20. LAS data (Cn2)  H Four scenarios were used to calculate H from Cn2 : Scenario 1: Ta, u* and L from CSAT3 (RM Young); ET used in the Bowen Ratio correction for the LAS was from the EC. Calculate Ft, T* and H directly. Scenario 2: Ta and u* from CSAT3 (RM Young); ET used in the Bowen Ratio correction for the LAS was from EC. Calculate L, Ft, T* and H iteratively.

  21. LAS data (Cn2)  H Four scenarios were used to calculate H from Cn2 : Scenario 3: Ta and u from CSAT3 (RM Young; ET used in the Bowen Ratio correction for the LAS was from EC. Calculate u*, L, Ft, T* and H using TCLI method. Scenario 4: Measured Rn (NR01), G (HFT), Ta (HMP) and P (PTB110); u from CSAT3 (RM Young). Calculate u*, L, Ft, T*, H and ET iteratively (three-concentric-loop-iterative method). --- note this is the most generally used method.

  22. Conclusions 1. Good agreement was obtained between H measured by CSAT3 and RM Young 81000 3-D sonic anemometers 2. H measured by Scintec BLS900 compared well with both EC systems (CSAT3 and RM Young). Thank you!

  23. Questions?

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