|TITLE||CHANGES IN THE CONTRIBUTION OF MOISTURE FROM THE MEDITERRANEAN BASIN TO THE CONTINENTAL PRECIPITATION FROM 1980 ONWARDS: A LAGRANGIAN ANALYSIS|
|AUTHORS||Anita Drumond (1)|Luis Gimeno (1)|Ricardo Garcia-Herrera (2)|Raquel Nieto (1)|
- Universidade de Vigo, Ourense, Spain
- Universidad Complutense, Madrid, Spain
|ABSTRACT||Previous studies indicate some increasing in the evaporation averaged over the Mediterranean basin in the last three decades. In this work we use an objective 3-D Lagrangian model (FLEXPART) to identify possible changes in the moisture contribution from this source to the continental precipitation during the period.
The method is based on the movement of a large number of air particles using 3D data from ERA-Interim reanalysis. The flow is described by the position of the particles and by the time. The increases and decreases in moisture along the trajectory can be calculated through changes in specific humidity (q) with time (being recorded every 6 hours). Adding these changes for all the air particles residing in the atmospheric column over an area, we can obtain a measure of the surface freshwater flux E-P (the evaporation minus the precipitation rate). For this study we track (E-P) from the Mediterranean basin forward in time along the trajectories, limiting the transport times to 10 days. The forward method allows us to investigate the role of the basin as source of moisture, identifying those particles that leave it and following them to find where they lose moisture. Extended winter (E-P) fields (from October to April) were obtained for the 1980-2012 period.
Climatologically, the contribution of moisture from the Mediterranean basin to the winter continental precipitation can be identified in a sink domain expanding from the northern Africa towards Europe and the western Asia, and it reaches higher values over the central-east European regions. A preliminary trend analysis of the (E-P) fields suggests some changes in the contribution of moisture from the basin during the period. It increased towards some climatological sinks of moisture (e.g. areas close to the Black Sea), while it reduced towards others (e.g. the Southern Europe). Results also suggest that new sink regions may be configured during the period studied. A decadal analysis is being conducted to provide more conclusive statements concerning the alterations in the moisture transport during the period.|