1. “Straw man” conceptual design for a LPB Field experiment
Based on discussions of PLATIN breakout group
VPM6
Miami, April 24-25, 2003
Presentation by Dennis Lettenmaier
(Modified March 11, 2005)

2. Scientific Motivation for a PLATIN field experiment (“PLATEX”)
Strong interannual and interdecadal climate and streamflow variations and trends
Confounding effects of land use change: deforestation, intensive agriculture trends and urbanization.
Unknown effect of aerosols advection from biomas burning from tropical areas
Strong role of MCS in total precipitation

3. La Plata basin Soil moisture Hydrologic cycle effects SST Anomalies
(Atl & Pac)
Variability and
trends
Applications to
hydrology

4. La Plata
Parana
Paraguay
Uruguay

5. River discharge
The potential for flooding occurs at any time of the year
The largest contribution during flood episodes comes from the Paraná River
Taken individually, both the Paraná and the Uruguay rivers can at least triple the mean river discharge during flood events
Motivation

6. Amplification of the precipitation signal in the streamflow

7. Flow in Itaipu Dam Potential causes:
rainfall increase due to climate variability
land use change
Ten years mobile mean

8. Approximate Tier 2 domain

9. Micrometeorological Observations on Surface Flux Towers
In the Brazilian Portion of the La Plata Basin

10. Field experiment conceptual design
Three tiers:
Tier 1: selected paired catchments (min two) with contrasting agriculture and natural forest land use (Tier 1 domain area ~10 – 50,000 km2; individual catchments probably o(1000 km2)
Tier 2: regional scale 200,000 km2 (middle Parana and Uruguay River basins)
Tier 3: entire La Plata basin (o(2,000,000 km2) – GEWEX CSE)

11. PLATEX conceptual design (cont.)
Design would include:
Semi-permanent (multi-year) observations throughout Tiers 1-2, but focused on Tier 1 (monitoring). Would include supplement rain gauge network and streamgauges, flux towers, in situ soil moisture, wind profilers and other micromet, and ideally permanent precipitation radar coverage in Tier 1
At least 2 IOPs of ~ 2 months each, one each in spring and fall. IOP observations could include: cloud microphysics (aircraft), supplemental ground-based atmospheric measurements (radar? lidar?), supplemental in situ precipitation and other surface observations; radiosonde enhancement, aircraft soil moisture, aerosol, energy flux and perhaps other measurements

12. PLATEX conceptual design (cont.)
Timing: Initiate semi-permanent observations in 2006 (?), first IOP ~2007/2008
Other potential linkages – satellite missions in proposed time frame – GPM (potential for PLATEX as verification site), SMOS (possibly), EOS/Terra and Aqua, others?
Potential CEOP reference site
Possible justification (and beneficiary) of enhancements in surface observation network (especially precipitation radar)

13. Practical Issues and Implications
Flood impacts on cities and huge flood plains, with associated economic impacts
Hydropower production sensitivity to streamflow variations
Navigation sensitivity to stream discharge variations

14. Justification for suggested location
It is in the path of the average of low level moisture flow, as well as aerosols; it is also an area of maximum (mean and extreme) precipitation
Mid-Parana basin is major source of runoff in the largest floods
Strong contrasts in land use change (extensive land conversion from forest to agriculture in Brazilian part of domain; Argentinian portion is closer to natural condition).