Surface conductance and evaporation from 1 km to

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

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

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

Surface evaporation = canopy + soil evaporation • PM equation for surface & canopy evaporation • fraction f of equilibrium rate at soil surface: • where CSIRO. Surface conductance and evaporation from 1 -km to continental scales using remote sensing MODIS 15 A 2 remote sensing

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

Gs sensitivity analysis D A 0. 5 200 2. 0 f gsx 0. 003 0. 009 CSIRO. Surface conductance and evaporation from 1 -km to continental scales using remote sensing 800 0. 8 0. 2

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

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

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

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

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

Data • Meteorological data • Daily values of solar radiation, Tmin, Tmax and H 2 O vapor pressure from SILO database, 2000 -2005 • MODIS data 2000 -2005 • 8 -day/1 km MOD 15 A 2 LAI from Distributed Active Archive Center of NASA, • Yearly/1 km MOD 12 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

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

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

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

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

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

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

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

CSIRO Marine & Atmospheric Research Ray Leuning Phone: 61 2 6246 5557 Email: ray. leuning@csiro. au http: //www. dar. csiro. au/lai/ozflux/ Thank you Contact Us Phone: 1300 363 400 or +61 3 9545 2176 Email: enquiries@csiro. au Web: www. csiro. au CSIRO. Surface conductance and evaporation from 1 -km to continental scales using remote sensing