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Amazonian deforestation:experiments with the RegCM
GROUP 3:
Rosmeri de Rocha (Brasil),
Yamina Silva (Peru),
Daniel Martinez (Cuba)
ICTP Workshop on the Theory and Use of Regional Climate Models 26 May - 6 June
Objectives:
•Making a first test of the RegCM3 model’s capability to reproduce the main climatic features in South America.
• Preliminary assessment of the immediate climatic consequences of land use changes in the Amazon forest.
Experiments
• January 1998 (From 16 Dec.1997 to 01 Feb. 1998)• Number of grid points: 81x69x18• Grid size: 80km (Mercator)• Time step: 200s• Convective scheme: Grell + FC (d=60 min)
Landuse1) Amazon forest (landuse=6) EXP12) Forest replaced by short grass (2) EXP2
The Domain
Forest was changed With Short grass
Total Precipitation: With Forest (EXP1)
Underestimation of precipitation over the Amazon area
Observed Simulated
Mean Temperature: With Forest (EXP1)
Simulated temperatures are lower than observed
Observed Simulated
Low level circulation (850 mb)
low level jet Over Amazon area the simulated winds
are weaker than reanalysis
Observed Simulated
High
Trough
High
Trough
The model reproduces the more important features of the summer circulation over South America
Observed Simulated
Upper level circulation (200 mb)
Differences between simulated parameters:
Short grass - Forest
Decrease in precipitation
Increase in precipitation
Local temperature increase reaching until 5°C
Differences between simulated parameters:
Short grass - Forest
The increase in maximum temperature is greater than in the minimum temperature
Foliage TemperatureGround Temperature
Ground and foliage temperature is higher in the short grass in the Amazon region, and is lower in other areas
Differences between simulated parameters:
Short grass-Forest
Differences between simulated parameters: Short grass-Forest
Dryer
Moister
Differences between simulated parameters: Short grass-Forest
Over the Amazon the lower level winds ( σ=1) became more intense in the short grass
Diurnal cycle
AM NE
SE
AM NE
SE
Diurnal cycle of convective precipitation (Short grass v.s. forest)
Short grass
Forest
More important impacts: -increase of the afternoon precip. in the SE-decrease of nocturnal precip. in the AM.
Minimum impact in the NE
Diurnal cycle of sensible heat (Short grass and forest)
AM NE
SEShort grass
Forest
More important impacts:
- increase of the afternoon sensible heat in the AM an SE.
Minimum impact in the NE.
Diurnal cycle of evapotranspiration (Short grass and forest)
AM NE
SE
Short grass
Forest
The more impact is: -Decrease in the AM -increase in the SE of the afternoon evapotranspiration
Minimum impact in the NE.
Control run:
• the model adequately reproduces the main features of the regional circulation.
• Underestimates precipitation and temperature In the Amazonian region.
In January 1998 simulation:
Preliminary results
Preliminary results
Deforestation impactsLocal effects:
Central Amazon:- lower precipitation and reduce the nocturnal precipitation - warmer air
- dryer soil - lower evapotranspiration and higher sensible heat
Peruvian Amazon:- increase of the total precipitation
Remote effects:
- increase of the precipitation and evapotranpiration in the SE- Minimal effects in the NE
Some problems
The intense precipitation in the east boundary diminished the Northeast trade winds and so the convergence in the Amazon region.
Is this responsible for lower precipitation in the Amazon?
Possible solution: move away the east-west boundaries
Thanks !!!
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