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We will now simulate the eruption in January to investigate how the dispersion changes by season–specifically in the winter when the equator-pole temperature gradient peaks. We hope to determine if the variation by season exceeds that by week and if so, the patterns that characterize winter ash dispersal.
January 1-3, 2010
Simulation of Particle Positions for January 1-3 Eruption
Image 8: 3-day ash dispersal simulation for Eyjafjallajokull for eruption date of January 1-3, 2010. The plume initially moves towards the southwest and then begins to rotate anti-cyclonically (in conflict to what theory Immediately moves anticyclonically in conflict with what theory would predict about the mean flow near the north pole where the Earth's rotation has a strong influence. Additionally, ). The southern tip of the plume that laters moves southward and deflects to the east rather than to the west as the right-ward deflection from the coriolis force would predict. The plume ultimately wraps around Iceland.
Ash Dispersal by Plume Arrival Time for January 1-3 Eruption
Image 9: 3-day Ash dispersal by arrival time for Eyjafjallajokull for eruption date of April 1, 2010. The ash spreads in a circle around Iceland and reaches both the U.S. and Europe.
In order to determine if any dispersal patterns characterize the month of January or the winter months more broadly we will now look at a simulation a week later in January to look for similarities.
January 8-10, 2010
Simulation of Particle Positions for January 8-10 Eruption
ultimately plume moves towards pole both in cyclonic and anticyclonic spirals
Image 10: 3-day ash dispersal simulation for Eyjafjallajokull for eruption date of January 8-10, 2010. Ultimately the plume stretches around the pole in both cyclonic and anticyclonic directions.
Ash Dispersal by Plume Arrival Time for January 8-10 Eruption
Image 11: 3-day Ash dispersal by arrival time for Eyjafjallajokull for eruption date of January 8, 2010. The ash spreads both towards the northeast and towards the southeast.
The ash dispersal by plume arrival images for the eruptions from January 1-3 and from January 8-10 do not exhibit any prominent similarities–the dispersal in the first week of January forms a circle around Iceland whereas in the second week it moves only northeast and southeast in separate streams. Thus we cannot identify any large scale trends for the January dispersals.
We will not look at simulations for the warmer month of July. We would anticipate that the ash disperse over a smaller area in July for the lower temperature gradient should result in slower zonal winds.
July 1-3, 2010
Simulation of Particle Positions for July 1-3 Eruption
northward and anti-cyclonically
Image 12: 3-day Ash dispersal by arrival time for Eyjafjallajokull for eruption date from January 1-3, 2010. The ash forms various spiraling patterns as it spreads into different regions. It may have been swept into different eddy cells.
Ash Dispersal by Plume Arrival Time for July 1-3 Eruption
Image 13: 3-day Ash dispersal by arrival time for Eyjafjallajokull for eruption date of July 1, 2010. The ash spreads north in both east and west directions. The northeastward flow also extends south in a counter-clockwise spiral.
I will now look at a simulation for the following week in July to search for larger scale dispersal trends for the month.
July 8-10, 2010
Simulation of Particle Positions for July 8-10 Eruption
moves poleward cyclonically.
Image 14: 3-day Ash dispersal by arrival time for Eyjafjallajokull for eruption date from July 8-10, 2010. The ash forms initially moves southeastward and then begins to spiral counter-clockwise towards the pole. The counter-clockwise motion towards the pole confirms theoretical predictions about the effect of the coriolis force at higher latitudes. In the final day, the ends of the plume deflect eastward. They may have been caught in eddy cells.
Ash Dispersal by Plume Arrival Time for July 8-10 Eruption
Image 15: 3-day Ash dispersal by arrival time for Eyjafjallajokull for eruption date of July 8, 2010. The ash splays northward.
Similar to those for January, the two July simulations did not demonstrate any major similarities. I did not identify any dispersal trend for July.
Conclusions
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 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.
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