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Towards monitoring drought conditions in Sicily using an energy balance approach

Stephan Niemeyer
Jürgen V. Vogt
SN

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Stephan Niemeyer

Résumé du colloque

The recent occurrence of severe and prolonged drought conditions in various regions of Europe, such as, for example, in Sicily 1988-1989, has emphasised the need for the development of adequate monitoring tools at regional to sub-continental scales. In the present study, the moisture status of the land surface is monitored using the daily evolution of the evaporative fraction (EF). This quantity is an indicator of the moisture status of the land surface, mainly consisting of natural vegetation and agriculture. As long as moisture is available, energy will be used for its evaporation. With no moisture left, all available energy will be directed into the sensible heat flux and EF will approach zero. In order to derive spatially resolved information on the water stress of vegetation, different data sources have to be combined. In general, remote sensing data provide a high spatial resolution, but few physical parameters, while point data from surface measurements show high accuracy, but are not spatially resolved. Thematic data like landuse classifications give qualitative information of the surface cover, but remain static in time. An energy balance estimation has been performed for Sicily using daily meteorological data from surface stations, daily remote sensing data from NOAA AVHRR and land cover / landuse data from the European CORINE land cover classification. The sensible heat flux (H) has been estimated from the difference of radiometric surface temperature and surface-measured air temperature, and the formulation of a bulk aerodynamic resistance. The latent heat flux (LE) is determined as the residual of the difference between available energy (Rn - G) and sensible heat flux (H) which finally gives the evaporative fraction as LE / (Rn - G). The results of this study show a realistic evolution of the EF during the summer season and allow for the spatially resolved monitoring of the moisture status at a regional scale.

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Section :
La télédétection optique et radar et la géomatique pour la gestion des problèmes environnementaux
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La télédétection optique et radar et la géomatique pour la gestion des problèmes environnementaux
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Abdou Bannari
host icon Hôte : Université d’Ottawa

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Thème du colloque :

La télédétection optique et radar et la géomatique pour la gestion des problèmes environnementaux
Towards monitoring drought conditions in Sicily using an energy balance approach
Stephan Niemeyer