WCRPGEWEX Pathway to LANDFLUX

1
WCRP/GEWEX Pathway to LANDFLUX

• 1) CloudClimate Feedback Problem Led to
• ISCCP, SRB and GPCP
• 2) Important (leading) Sources of Uncertainty for
  SRB
• are Land Surface (Sea Ice) Properties
• Temperature, Emissivity, Spectral Albedo
• 3) Completion of Global (Atmospheric) EW Cycle
  Requires Land (Ice) Surface Turbulent Fluxes
• 4) Connection of Climate Change to Human
  Interests
• Requires Land Hydrology Predictions
• Water Storage (Lakes, Soil Moisture, Snow/Ice,
  Acquifer) and Runoff (Discharge, Floods)

2
Data Sets Potential Status

• DEM and Runoff models Y
  Y
• Albedo (spectral) Y
  Y
• Skin Temperature (diurnal) Y
  R
• (emissivity) Y R
• Vegetation Properties Y
  R
• (hi-res description) Y R
• Surface Meteorology Y
  Yr
• Precipitation
  Y Y
• Snow Water Amount Y
  R
• Flooding (standing water) Y
  R
• Water Levels ( discharge) P
  R
• Soil Moisture
  P R
• Water Storage P
  R
• Surface Radiation Y Y

3
Methodology Ideas for Fluxes

• (Wood) Different formulae approaches driven by
  radiation (incoming) and precip, wind, Ta Qa
• (Lin) ET estimate from microwave index plus
  radiation
• (Betts) Given Surface Radiation, RH and Precip,
  estimate Evaporative Fraction
• (Houser/Rodell) Assimilation Approaches
  (eventually fully coupled get Houser slide)
  (force off-line land surface model GSWP
  approach)
• (Beljaars) Re-analysis derived results
• (Entekabi) Straight ET estimate from bulk
  equations using remote sensing inputs
  formulation is separated into different
  contributions (not veg-type dependent explicitly)
  essence radiation sensible heat flux reduced
  by EF-based factor
• (Basic) Bulk formulae for SH and ET with remote
  sensing inputs
• ---- VALIDATION OF RESULTING PRODUCTS

4
Some Issues

• 1. Formulation of Land Surface Fluxes in terms of
  measurable quantities
• 2. Vegetation Structure Function not available
  in needed detail
• 3. Content (and organization/access) of Flux
  Tower data (how useful are these data without
  radiation and/or soil moisture/hydrology ie,
  what is the best verification??, also issue of
  location)
• 4. How to treat Spatial Heterogeneity
• 5. Figure out how to improve large-scale
  hydrological parameters used in models and
  derived from observations

5
Some Recommendations

• We need an international coordination of
  landflux sites (like BSRN model)? should
  augment BSRN sites or bring flux-tower sites up
  to BSRN standards energy/water/carbon (with
  hydrology)
• We need to make recommendations for Albedo
  workshop
• We need to stimulate progress on multi-satellite
  analyses ltsimultaneous multi-variate retrievalgt
  and data-model analyses of land surface fluxes
  and hydrology

6
Some Actions

• ??? Organize Conduct Albedo Workshop
• SPRING 08
• ??? Organize Conduct Land Surface
• Temperature (Skin and Air) Workshop
• SPRING 08
• ??? Organize Conduct Flux Product Comparison
  Workshop
• FALL 08

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Observation Constrained Hybrid PBL/Land
Model LandFlux Algorithm Proposal

• Way forward
• Year 1 Proof-of-concept
• Year 2-3 20 year product
• Eval/Calibration plan

• Observational Constraints
• (Consistent 1983-current)
• Surface Radiation (i.e. ISCCP)
• Precipitation (i.e. GPCP)
• Surface Skin Temperature
• Near-Surface T RH
• Innundation
• Albedo
• Vegetation Phenology LAI
• Snow Cover SWE
• Soil Moisture (if available)

• LandFlux Products
• Surface Radiation Balance
• Latent Heat Flux
• Sensible Heat Flux
• CO2 Flux
• Momentum Flux

Land Model