Assessing the impacts of the 2003 hot and dry spell with SPOT HRVIR images time series over south‐western France

Abstract

A severe heatwave affected southern Europe and, in particular, south‐western France during the summer of 2003. The area was subjected to a severe dry spell with high temperatures and very little precipitation during a nearly 4‐month‐long period. A series of monthly 20‐m spatial resolution images, acquired between 2002 and 2003 by the SPOT HRVIR (High Resolution Visible–Infrared) was used to examine the impact of the dry and hot spell over a 50 km×50 km area of south‐western France. The use of the high spatial resolution data permitted the distinction of the various land surface types, and facilitated the diagnosis of the hot and dry spell effects for each class. The Normalized Difference Vegetation Index (NDVI) time series of the four principal vegetated surfaces (meadow, deciduous forest, wheat and maize) reveal different responses to the dryness and hot spell. A significant shortening of the 2003 phenological cycle was observed for the meadows, but the response was not as clear for the deciduous forests. For the crop surfaces, a shortening of the cycle is observed, although the impact of the drought was translated differently as a function of the crop type.

Acknowledgments

This work was made possible through the support of the French Minister in charge of Research (‘Réseau Terre et Espace’), the Minister in charge of Environment (GICC programme), the CNES, and the Région Midi‐Pyrénées Council. The authors wish to express their sincere gratitude to CNRM/Méteo France, which provided the meteorological datasets. F. Cabot and A. Meygret, from CNES, are gratefully acknowledged for providing up‐to‐date calibration coefficients.