The Advection of Mesoscale Atmospheric Vortices over Reykjavík

On 12 August 2009, a series of satellite images revealed asymmetric shedding of atmospheric vortices in the
lee of Mt. Snæfellsjökull, and their passage a distance of 120 km across Faxaflói Bay and over the city of
Reykjavík in West Iceland. After landfall, the vortices were detected by a network of surface weather stations.
These observations are presented and with the aid of a numerical simulation, they are discussed in view of
existing theories of orographic wakes and vortex shedding. In general, the flow is in line with existing
knowledge, but there is a remarkable absence of vortices with anticyclonic rotation. Atmospheric conditions
for vortices of this kind are most often favorable in late winter and spring and they are a forecasting challenge.