The intense 2007-2009 drought in the Fertile Crescent: Impacts and associated atmospheric circulation

摘要

The historical region of Fertile Crescent (FC) was recently hit by an intense and prolonged drought episode during the two hydrological years spanning between 2007 and 2009. Here, we characterize the temporal and spatial extents of this extreme drought at the monthly and seasonal scales and perform a first assessment on the associated impact in the hydro-meteorological fields, as well as the consequent influence on vegetation dynamics and cereal productions.This episode corresponds to the driest two-year case for the FC area since 1940, although just slightly drier than the 1998-2000 drought. Precipitation decline was mostly noticeable over Iraq (up to 70%), with the suppression of rainfall particularly acute during the first hydrological year (2007-2008). From the meteorological perspective, winter and transition months were dominated by high pressures that inhibited synoptic activity entering from the eastern Mediterranean and favoured relative north-easterly winds and drier air masses with low convective instability.The impact of the 2007-2009 drought in vegetation was evaluated with Normalized Difference Vegetation Index (NDVI) obtained from VEGETATION instrument. It is shown that large sectors of south-eastern Turkey, eastern Syria, northern Iraq and western Iran present up to six months of persistently stressed vegetation (negative NDVI anomalies) between January and June 2008. During the following dry year (2008-2009) dry areas are restricted to northern Iraq with up to five months of stressed vegetation. Finally we looked at the impacts on cereal production (wheat and barley) in the region and it is shown that the major grain-growing countries in the area (Syria. Iraq and Iran) were significantly affected by this drought, particularly in the year 2008