Very long winter dry spells in the Mediterranean basin: spatio-temporal variability and impact on cereal production in Spain

This study concerns the long winter sequences without rain on the scale of the entire Mediterranean basin scale. Objectives are (i) to define theses extreme events as geographical and climatological objects characterized by a location, a spatial extension and a temporal length and (ii) measured impacts of these events on the cereal production in Spain. 76 events of Very Long Dry Spells (eVLDS) are detected over the 1957-2013 period. These eVLDS are grouped into four typical recurrent configurations on the scale of the Mediterranean basin: North-East, West, scattered & localised and South-East. The eVLDS configurations are associated with anticyclonic conditions located about 1 000 km northwest of the impacted areas. The eVLDS have a greater impact on barley, wheat and oat yields (winter crops grown through rainfed agriculture) than rainfall totals and seasonal dry day ratios.