Scintillometer and eddy covariance comparisons over sagebrush and invasive cheatgrass communities in Idaho Scintillometer and eddy covariance comparisons over sagebrush and invasive cheatgrass communities in Idaho EPSCoR Project Suported by NSF AuthorsAuthors University of Idaho University of Idaho Wenguang Zhao, Rick Allen, Clarence Robison, Jeppe Kjaersgaard, Ricardo Trezza, Aureo Oliveira, Ramesh Dhungel Idaho State University Idaho State University Matt Germino Boise State University Boise State University Venkat Sridhar Wageningen University Wageningen University Henk de Bruin University of Idaho University of Idaho Wenguang Zhao, Rick Allen, Clarence Robison, Jeppe Kjaersgaard, Ricardo Trezza, Aureo Oliveira, Ramesh Dhungel Idaho State University Idaho State University Matt Germino Boise State University Boise State University Venkat Sridhar Wageningen University Wageningen University Henk de Bruin BackgroundBackground 1. Sensible heat flux (H) is an important energy dissipation in surface energy balances and evapotranspiration (ET) studies. 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. 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. 3. Large aperture scintillometry (LAS) is an alternative method to estimate H from a relatively large footprint (source) area. 1. Sensible heat flux (H) is an important energy dissipation in surface energy balances and evapotranspiration (ET) studies. 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. 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. 3. Large aperture scintillometry (LAS) is an alternative method to estimate H from a relatively large footprint (source) area. QuestionsQuestions 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? 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? 2. How does the H calculated by the LAS measurement compare to the traditional EC measurement result? 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? 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? 2. How does the H calculated by the LAS measurement compare to the traditional EC measurement result? Macks Inn Site (Alpine Forest) Raft River Site (Cheatgrass) (Cheatgrass) Hollister Site (Sage Brush) Hollister Site (Sage Brush) Experiment sites InstrumentationInstrumentation Hollister Site: Sagebrush LAS Transmitter LAS Receiver Eddy Covariance Site 1 Eddy Covariance system Radiation System Soil Sensors Raft River Site: Cheatgrass LAS: Transmitter A & Receiver B Eddy Covariance Site 1 Macks Inn Site: Alpine forest (south tower) Macks Inn Site: Alpine forest (north tower) Results and Discussions LAS data (C n 2 ) H Four scenarios were used to calculate H from C n 2 : Scenario 1: Ta, u* and L from CSAT3 (RM Young); ET used in the Bowen Ratio correction for the LAS was from the EC. 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. Four scenarios were used to calculate H from C n 2 : Scenario 1: Ta, u* and L from CSAT3 (RM Young); ET used in the Bowen Ratio correction for the LAS was from the EC. 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. LAS data (C n 2 ) H Four scenarios were used to calculate H from C n 2 : 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. Four scenarios were used to calculate H from C n 2 : 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. ConclusionsConclusions Good agreement was obtained between H measured by CSAT3 and RM Young D sonic anemometers 2. H measured by 2. H measured by Scintec BLS900 compared well with both EC systems (CSAT3 and RM Young). Thank you! Good agreement was obtained between H measured by CSAT3 and RM Young D sonic anemometers 2. H measured by 2. H measured by Scintec BLS900 compared well with both EC systems (CSAT3 and RM Young). Thank you! Questions?Questions?