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

3. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing  Traditionally, the “aerodynamic” model is used: where : T sA and T a : aerodynamic surface and air temperatures Assume T sR = T sA Differences between T sA & T sR are small … Land surface evaporation from surface temperature

4. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing Surface temperature T aerodynamic T Remote sensing T aerodynamic T Remote sensing Tumbarumba Virginia Park

5. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing But… Sensible heat flux simulations are poor Measured Modelled Tumbarumba Virginia Park Leads to poor estimates of evaporation

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

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

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

9. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing Surface conductance (Leuning et al., 2007): Surface conductance 6 parameter model, 4 kept constant

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

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

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

13. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing E eq & E RS versus E meas for 15 FluxNet sites E eq - Equilibrium evaporation E RS - PM Equation with G s & MODIS L AI E meas (mm/d) E eq (mm/d) E RS (mm/d) 2 free parameters: g sx & f

14. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing Application of E RS to Murray Darling Basin Long-term water balances of gauged catchments Thus Invert evaporation model to solve for g sx & f in model for G s Parameters for 3 rainfall zones from 135 catchments,

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

16. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing Data Meteorological data Daily values of solar radiation, T min, T max and H 2 O 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

17. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing Time series of E, P & L ai for two catchments near Tumbarumba

18. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing 5-year average E RS vs E WB for 135 catchments

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

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

21. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing Runoff: R Rs and R Budyko

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

23. CSIRO. Surface conductance and evaporation from 1-km to continental scales using remote sensing Conclusions and further work PM equation, G s model & MODIS L ai Builds in energy balance from start useful for estimating evaporation at catchment scale G s model – biophysical with two parameters g sx and f Overestimation of E due to uncertainties in MODIS L ai 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?

24. 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/