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By simulating Eyjafjallajokull for various eruption dates, I sought to investigate how the circulation patterns changed both seasonally and weekly and whether the seasonal versus weakly variations dominated the ash dispersal patterns. Simulations showed that the weekly changes in atmospheric circulation patterns dominated any seasonal trends. Eyjafjallajokull sits at the boundary between two different air masses (between the polar and Eddy eddy regimes--air nearer to the poles is generally cold and dry whereas at mid-latitudes it is warmer and also influenced by the tropics). This region is influenced by the North Atlantic Oscillation (NAO) phenomenon in which the circulation patterns vary dramatically.
The pronounced weekly variation in the ash dispersal may result from the varying Eddies eddies that pass by the region of the volcano. The Eddies eddies are mesoscale (order of 1000 km), and thus which Eddy eddy occupies the region during the eruption would serve as the main determinant of the ashes' dispersal. Moreover, the local variance has significant downstream effects. . In simulation for the eruption on January 1, 2010, the ash reached the U.S. whereas in the simulation a week later on January 8, 2010, the ash reached Russia.
In order to understand over what time periods the ash dispersal would vary, one must look into the time scales of the Eddys eddys in the Icelandic region. Further simulations should explore variations in dispersal from daily changes to the eruption date.
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