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Surface conductance and evaporation from 1-km to continental scales using remote sensing

This study explores the estimation of energy and water fluxes at multiple scales using remote sensing data. It introduces a new approach that combines the Penman-Monteith equation with MODIS evaporation data. The study examines surface and canopy evaporation, canopy conductance, and applies the approach to the Murray Darling Basin. The results show the potential to accurately estimate evaporation and improve understanding of water balance dynamics. Contact CSIRO for more information.

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Surface conductance and evaporation from 1-km to continental scales using remote sensing

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  1. Surface conductance and evaporation from 1-km to continental scales using remote sensing Ray Leuning, Yonqiang Zhang, Amelie Rajaud, Helen Cleugh, Francis Chiew, Lu Zhang & Kevin Tu CSIRO Marine & Atmospheric Research, CSIRO Land & Water 5 February 2008

  2. The challenge Estimate energy & water fluxes at multiple scales CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  3. MODIS evaporation – a “new” approach • Penman-Monteith equation for surface evaporation: • where CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  4. MODIS15A2 remote sensing Surface evaporation = canopy + soil evaporation • PM equation for surface & canopy evaporation • fraction fofequilibrium rate at soil surface: • where CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  5. Canopy conductance • Canopy conductance (after Kelliher et al., 1995; Leuning, 1995) CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  6. 0.5 800 200 2.0 0.8 0.003 0.2 0.009 Gs sensitivity analysis D A f gsx CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  7. Time series for Fluxnet sites: Evergreen Deciduous CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  8. Time series for Fluxnet sites: Conifer Savanna CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  9. ERS - PM Equation with Gs & MODIS LAI Eeq - Equilibrium evaporation Eeq (mm/d) ERS (mm/d) Emeas (mm/d) Emeas (mm/d) Eeq & ERS versus Emeasfor 15 FluxNet sites 2 free parameters: gsx & f CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  10. Application of ERS to Murray Darling Basin • Long-term water balances of gauged catchments • Thus • Invert evaporation model to solve for gsx & f in model for Gs • Parameters for 3 rainfall zones from 135 catchments, CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  11. Landcover & gauged catchments – Murray Darling Basin CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  12. Data • Meteorological data • Daily values of solar radiation, Tmin, Tmax and H2O vapor pressure from SILO database, 2000-2005 • MODIS data 2000-2005 • 8-day/1km MOD15A2 LAI from Distributed Active Archive Center of NASA, • Yearly/1km MOD12 land cover • Runoff + rainfall data • Daily runoff at 135 gauged catchments of MDB • Daily precipitation from SILO CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  13. Time series of E, P & Laifor two catchmentsnear Tumbarumba CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  14. 5-year average ERS vs EWBfor 135 catchments CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  15. P & ERS– Murray Darling Basin CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  16. Water supply limit Energy limit Remote sensing Budyko Water balance Zhang CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  17. Runoff: RRs and RBudyko CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  18. Runoff maps CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  19. Conclusions and further work • PM equation, Gs model & MODIS Lai • Builds in energy balance from start • useful for estimating evaporation at catchment scale • Gs model – biophysical with two parameters gsx and f • Overestimation of E due to uncertainties in • MODIS Lai • Single value of f for each rainfall zone – should be variable • No constraint by water balance • Further work • Combine PM combination equation with catchment water balance • Improve soil evaporation component • Use microwave remote sensing for f? CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing

  20. Contact Us Phone: 1300 363 400 or +61 3 9545 2176 Email: enquiries@csiro.au Web: www.csiro.au Thank you CSIRO Marine & Atmospheric Research Ray Leuning Phone: 61 2 6246 5557 Email: ray.leuning@csiro.au http://www.dar.csiro.au/lai/ozflux/

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