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HYSPLIT Simulations for Eyjafjallajokull (Varying Eruption Date)
The simulations will be computed using HYSPLIT (https://www.arl.noaa.gov/hysplit/hysplit/), a model developed by the National Oceanic and Atmospheric Administration (NOAA)'s Air Resources Laboratory. The model is used for tracer transport and computes air parcel trajectories; it is similar to ESGlobe, which we used in Project II. Its computational approach employs a combination of the Lagrangian and Eulerian methodologies. The Lagrangian approach uses a frame of reference that moves with the air parcels and the Eulerian approach uses a fixed 3D frame of reference.
Although the eruptions contributing to the majority of ash fall lasted for 6 days, the simulations will cover the first three days of eruptions.
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Image 3: Shows the constant pressure surface for 500 mb on the second day of the eruption. The contour lines illustrate the wind patterns for horizontal wind flows on a constant pressure surface. Black The coriolis force balances the pressure gradient, and thus the flow follows the constant pressure lines. Black arrows illustrate the relevant flows around Iceland. The winds move eastward towards England and then south. They also move north-westwards.
Simulation of Particle Positions for April 14-16 Eruption
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Image 4: 3-day ash dispersal simulation for Eyjafjallajokull for actual eruption date of April 14, 2010. The plume initially moves north-eastward and then south-westard. As the plume moves northward it deflects to the east and as it moves southward it deflects to the west as predicted by the rightward deflection of the coriolis force in the northern hemisphere. The two layers closest to the Earth's surface spread the furthest.
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The simulations also give insights into our record of past volcanoes. We often research past volcanoes through the ash they deposited in Greenland ice cores. Given that in many of our simulations the ash from our Icelandic volcano did not reach its neighboring country, we may likely lack eruption recordings for many past volcanoes near Greenland.
Next Steps
My simulations did not demonstrate seasonal trends; in order to demonstrate seasonal trends, one should take the daily average of all dispersal simulations over the month of January versus the daily average over the month of July. Due to the daily variations, looking at individual days in January versus individual days in July did not show meaningful insights re seasonal trends.
It would also be interesting to look at the In order to understand the smallest time period over which changing the eruption date would cause the ash dispersal to vary. To do so, one must look into the time scales of the eddys in the Icelandic region. Further simulations should explore variations in dispersal from daily changes to the eruption date . (as opposed to daily averages over month-long periods to see seasonal trends).