Multi-site modeling of land surface-atmosphere exchanges at the 
extent of an agricultural Mediterranean region

Carlo Montes

Mediterranean regions are characterized by low rainfall amounts 
and a strong sea- sonality in its distribution. In these regions, 
evapotranspiration (ET) corresponds to the main component of the 
hydrological cycle, so that quantifying land surface-atmosphere 
exchanges is a crucial issue in order to assess climate-vegetation 
feedbacks or water consumption by plants. Re- cent advances in 
terms of modeling and remote sensing, mainly at the sub-regional 
level for full cover canopies, allow foreseeing the regional extent 
for complex surfaces such as sparse vegetation and row crops. This 
work proposes a modeling approach of soil-vegetation-atmosphere 
transfers that can be used at the extent of an agricultural region, 
combined with a parameter optimization procedure and optical and 
infrared remote sensing methods. Initially, a 1-D model with 
regional focus was developed to simulate the energy and water 
balance of a row crop (vineyard). The model was validated using 
ground-based data in southern France, and multi-criteria methods 
were used in order to perform a sensitivity analysis and model 
calibration. Secondly, remote sensing data were used in order to 
estimate watershed ET by using a contextual approach with 
Landsat and ASTER imagery. Finally, satellite estimates of ET and 
soil moisture measurements were used jointly in order to calibrate 
the model and to obtain multi-site simulations of the water balance 
on a set of points in the study area.