|TITLE||THE EFFECTS OF MEDITERRANEAN OSCILLATION AND WESTERN MEDITERRANEAN OSCILLATION ON SURFACE CLIMATE VARIABLES IN THE MEDITERRANEAN|
|AUTHORS||R Beranová (1), R Huth (1,2)|
- Institute of Atmospheric Physics, CAS, Prague, the Czech Republic
- Faculty of Science, Charles University, Prague, the Czech Republic
|ABSTRACT||Temporal and spatial variability of both temperature and precipitation in the Mediterranean is related to atmospheric circulation patterns such as the Mediterranean Oscillation (MO) and the Western Mediterranean Oscillation (WeMO). Atmospheric circulation is characterized in terms of circulation indices traditionally defined either based on normalized SLP differences between two distant locations close to centres of action or based on the Principal Components Analysis (PCA). However, in the majority of previous studies the MO and WeMO indices are defined only based on SLP differences between two stations.
The MO is described as a teleconnection pattern with opposite pressure and rainfall anomalies between the central–western and eastern Mediterranean areas. When the pressure increases in the western basin, a decrease is found in the east and vice versa. The MO index is defined by the Gibraltar – Lod dipole. The WeMO index is characterized by the San Fernando – Padua dipole. The positive phase corresponds to anticyclone over the Azores enclosing the southwest Iberian quadrant and low pressures in the Liguria Gulf, while its negative phase coincides with the Central European anticyclone located north of the Italian peninsula and a low pressure centre in the framework of the Iberian southwest. Both MO and WeMO PCA indices are computed as leading modes of SLP anomalies over the extended Mediterranean region (30°W–40°E, 30–60°N).
In this contribution we analyse relationships between the circulation indices and climate elements in the Mediterranean region. Climatic elements analysed are monthly means of the daily maximum and minimum, monthly precipitation amounts and monthly number of wet days (i.e., days with precipitation amount ≥0.1 mm). We compare impacts of different defined circulation indices (station vs. PCA) on surface variables. We also find out if the relationships are stable in time.|