The Advection of Mesoscale Atmospheric Vortices over Reykjavík

Hálfdán Ágústsson Belgingur-Institute for Meteorological Research, Icelandic Meteorological Office, and University of Iceland, Reykjavík, Iceland

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Haraldur Ólafsson University of Iceland, and Icelandic Meteorological Office, Reykjavík, Iceland, and Bergen School of Meteorology, Geophysical Institute, University of Bergen, Bergen, Norway

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Abstract

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.

Corresponding author address: Hálfdán Ágústsson, Institute for Meteorological Research, Orkugarði, Grensásvegi 9, 108 Reykjavík, Iceland. E-mail: halfdana@gmail.com

Abstract

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.

Corresponding author address: Hálfdán Ágústsson, Institute for Meteorological Research, Orkugarði, Grensásvegi 9, 108 Reykjavík, Iceland. E-mail: halfdana@gmail.com
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