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Long-term trends in uncertainty of element fluxes at the Hubbard Brook Experimental Forest

Long-term trends in uncertainty of element fluxes at the Hubbard Brook Experimental Forest. Mark Green, Donald Buso , John Campbell, Carrie Rose Levine, Gene Likens, Ruth Yanai. Element Fluxes. : Flux [mass per time]. : Concentration [mass per volume]. : Concentration [volume per time].

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Long-term trends in uncertainty of element fluxes at the Hubbard Brook Experimental Forest

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  1. Long-term trends in uncertainty of element fluxes at the Hubbard Brook Experimental Forest Mark Green, Donald Buso, John Campbell, Carrie Rose Levine, Gene Likens, Ruth Yanai

  2. Element Fluxes : Flux [mass per time] : Concentration [mass per volume] : Concentration [volume per time]

  3. Hubbard Brook White Mtn. Natl. Forest New Hampshire Hubbard Brook Experimental Forest White Mountain National Forest, NH Map courtesy of Dr. John Campbell, USFS

  4. Objective Our Guiding Questions Propagate some sources of uncertainty through flux estimates. How certain are our flux signals? Is there new information that may arise from quantifying uncertainty?

  5. Approach • Quantify uncertainty in annual fluxes into and out from Watershed 6 at HBEF • Nitrate • Silicon • Only a few sources of uncertainty are addressed so far

  6. UNCERTAINTY Natural Variability Knowledge Uncertainty Spatial Variability Measurement Error Temporal Variability Model Error Modified from Harmon et al. (2007)

  7. Model Selection Uncertainty

  8. Weekly Average Streamwater Concentration Time

  9. Linear Interpolation Streamwater Concentration Time

  10. -1.9% -3.7%

  11. Model Parameter Uncertainty

  12. Steps in Flux Calculation For every gap between samples: • Calculate mean concentration • Determine the inter-sample residuals based on season and date • Add a bootstrapped residual to the mean • Calculate annual flux

  13. Nitrate

  14. Silica

  15. Summary Nitrate • Uncertainty in model selection: 3% • Uncertainty in inter-sample mean: 17% Silicon • Uncertainty in inter-sample mean: 9% Maybe novel information in IQR:Median

  16. Next: More sources in streamwater, finalize precipitation, and propagate to net hydrologic flux.

  17. http://quantifyinguncertainty.org/

  18. UNCERTAINTY Natural Variability Knowledge Uncertainty Spatial Variability Measurement Error Temporal Variability Model Error Atmospheric Inputs Modified from Harmon et al. (2007)

  19. Alternative spatial models for precipitation in the Hubbard Brook Valley

  20. Alternative spatial models for precipitation in the Hubbard Brook Valley Coefficient of variation between models 0.83% 0.77% 0.24% 0.58% 0.36%

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