INVESTIGADORES
PESSACG Natalia Liz
artículos
Título:
Impacts of land use changes over southern South American climate: a modeling study using the MM5 regional model
Autor/es:
N. L. PESSACG; S. A. SOLMAN
Revista:
CLIVAR EXCHANGES
Editorial:
Layout & Printing
Referencias:
Lugar: Southampton; Año: 2011 vol. 16 p. 35 - 38
ISSN:
1026-0471
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 over these regions have been extended at the expense of deforestation and replacement of natural pastures. Land use/land cover changes (hereafter LULCC) may modify the exchanges of energy and moisture between the land surface and the atmosphere due to the control that land surface exerts on the partitioning of available energy at the surface between sensible and latent heat fluxes and the available water between evaporation and runoff. Besides that, the surface heterogeneity not only determines the microclimate but also affects mesoscale atmospheric circulations (Hartmann, 1994; Weaver and Avissar, 2001; Yang, 2004; Sertel et al., 2010).Over the LPB and Argentinean Pampas, there are some recent studies that suggest that the net warming and the strong reduction in diurnal temperature range could be associated with surface effects (Nuñez et al., 2008). Ferreira et al. 2006; Lee and Berbery 2009 and Blatter et al. 2010 showed evidence that the mechanisms associated with land use changes have an important impact on the local climate, particularly for temperature and precipitation and also for regional circulation patterns. Beltran-Przekurat et al. (2011) analyzed the impacts of LULCC over the LPB region and found that the shift from grass to agriculture led to cooler and wetter near-surface atmospheric conditions and warmer conditions resulted from the conversion of wooded grasslands or forest to agriculture. Most of previous studies are based on the traditional experimental setup for this kind of sensitivity experiments that consist of a single model realization representing the control climate and a single model realization representing the regional response to a given forcing, which is forced through the boundary conditions (at the lateral boundaries or at surface). The difference between the two simulations is then evaluated as the response to the given forcing. Nevertheless, in recent years, several studies have shown that regional climate simulations are affected by several sources of uncertainties, among these internal variability (de Elia et al. 2008; Solman and Pessacg 2011), consequently those differences should be taken into account before drawing conclusions about the significance of the regional climate responses to the external forcings (O’Brien et al. 2008). Taking into account these previous results and with the goal of understanding how the LULCC may affect the regional climate over southern South America, ensembles of sensitivity experiments for an idealized land use scenario using the Fifth-generation Pennsylvania-State University- NCAR nonhydrostatic Mesoscale Model (MM5) (Grell et al., 1994) were performed with the aim of identifying the physical signal of the internal variability inherent to the system due to LULCC. This study is a contribution to one of the objectives of the CLARIS-LPB Project concerning assessing and quantifying the impact of land use change in climate change on the LPB.