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 effects
Hydrologic cycle
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
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).