INVESTIGADORES
SOLMAN Silvina Alicia
congresos y reuniones científicas
Título:
Impacts of land-use change in Southern South American climate.
Autor/es:
PESSACG NATALIA LIZ; SOLMAN SILVINA ALICIA
Lugar:
Foz de Iguazú
Reunión:
Conferencia; The Meeting of the Americas, AGU; 2010
Institución organizadora:
American Geophysical Union
Resumen:
La Plata Basin (LPB) and the Argentinean Pampas are two of the
most important agricultural regions in the world. In the last decades
the areas devoted to agriculture production over the La Plata basin
region have been extended at the expense of deforestation and
replacement of natural pastures. These changes in land use and land
cover may modify the exchanges of energy and moisture between the
land surface and the atmosphere, through changes in albedo,
aerodynamic roughness and root depth, resulting in local and regional
changes in climate over the region. With the aim of analyzing and
understanding how these changes may affect the regional climate,
sensitivity experiments to land use/land cover change were performed
with the Fifth-generation Pennsylvania-State University-NCAR
nonhydrostatic Mesoscale Model (MM5). Based on observational
evidences of land use changes over South America, an idealized land
use scenario was defined, in which the natural land cover was replaced
by dry land crop pasture in three regions that were selected. This
highly idealized scenario has the purpose of evaluating what extent
large changes in land use may impact on the climatic characteristics
over the target region. Ensembles of one-year length experiments for
the land use change scenario and control simulations were compared.
The period simulated corresponds to 1989-1990 and the focus is on
DJF, the austral summer season. The changes in land cover over the
northern part of the La Plata Basin, where croplands replace evergreen
broadleaf and savannah, induced two feedbacks. On one hand, an
increase of albedo leads to a reduction of the surface temperature and
the sensible heat flux. On the other hand, a decrease of roughness
drives to a reduction of latent heat flux associated with a decrease of
the capacity of root for extracting soil moisture, mainly over
northeastern Argentina. The soil moisture showed large decreases
within the upper levels of the soil and the deeper layers of the soil
experienced an increase in soil moisture, probably due to the reduced
root length. The reduced availability of moisture near the surface
together with a relatively more stable planetary boundary layer
resulted in a decrease of low-level cloud cover and a decrease in precipitation, mainly due to a decrease in the intensity of heavy
precipitation events. In contrast, the southern part of the basin
presents the opposite conduct, as croplands replaces shurbland, a
decrease in albedo and a weak increase in surface temperature is
apparent. However, no significant changes in precipitation are
evident.