Investigating relationships between teleconnections around the Mediterranean and their influence on aerosol transport using a regional climate model (REGCM4)

Abstract

The Earth's climate is dependent on many factors, some of the most important are atmospheric teleconnection patterns. These are normally composed of two or more negatively correlated semi-permanent pressure systems of varying magnitude situated in distant locations. These variations have a strong influence on the circulation of the surrounding regions. This work focused on the following patterns: Central African-Caspian Oscillation, East Atlantic pattern, East Atlantic/Western Russia pattern, Mediterranean Oscillation, North Atlantic Oscillation, North Sea-Caspian Pattern, Scandinavian Pattern, Southern Europe-North Atlantic, and Western Mediterranean Oscillation. A very important factor that influences the climate in the mesoscale is the presence and nature of aerosol particles. Some particulates (such as dust) have the tendancy to reduce surface temperature, while others increase it (such as black carbon). Since aerosols are particulates suspended in the atmosphere, their presence in a particular location is strongly effected by wind speeds and direction. This brings out an important link between teleconnections and the transportation of aerosol particles. The Regional Climate Model (RCM), RegCM4.0, has been used to simulate the climate of 1984 to 2008 for a domain, covering most of the northern latitudes, and spanning from the North Atlantic to the Middle East, at 50 km resolution. A general method for calculating the indices for these patterns was identified and the respective indices were constructed from this simulation, as well as from reanalysis data (which was used as a reference). The interactions between the patterns and wind vectors were studied, as well as the interaction with aerosol concentration. This analysis has revealed many (both positive and negative) relationships between various teleconnections, as well as a tendency to induce large cyclic wind flows that extend over several pressure levels. Finally, this influence on circulation was related to correlation field maps that revealed the nature of aerosol transportation as a result of the value of the teleconnection indices.