A lagrangian analysis of the moisture transport during the 2003 drought episode over the Mediterranean region

In the last decades many studies have pointed out an increasing number of natural hazards associated with extremes in precipitation and drought conditions. Generally, dry and hot conditions across the Europe impact on the Mediterranean region. The Mediterranean is located at the border between the tropical climate zone and the mid latitude climate belt. Due to its large extension and diverse topography, it shows large climatic differences that make its climate scientifically interesting.  

The aim of this study is to analyze the moisture transport during the 2003 drought episode observed over the surroundings of the Mediterranean. The region was defined according to the 5th Intergovernmental Panel on Climate Change (IPCC) Assessment Report. The episode was identified using Standardized Precipitation Evapotranspiration Index (SPEI), calculated using monthly CRU (TS3.24.01) precipitation and potential evapotranspiration (PET). One of the crucial advantages of the SPEI over the other widely used drought indexes is its multi-scalar characteristics, which enable identification of different drought types. Therefore, the monthly SPEI-1, SPEI-3, SPEI-6, SPEI-12 and SPEI-24 indexes were used to identify the episodes on different time scales. This episode was the most severe during the period 1980-2015 according to the SPEI-1 analysis. Analyses of precipitation, potential evapotranspiration, omega at 500hPa, and vertically integrated moisture flux have been conducted to characterize the anomalous patterns over the region during the event. A Lagrangian approach was then applied in order to investigate possible changes in the moisture transport from and toward the Mediterranean region during the episode. This approach is based on the FLEXPART model integrated with the ERA-Interim data set.