Extended Abstract (256K)16.3
Observations and numerical simulations of a wake and corner winds in a strong windstorm over Iceland
Haraldur Olafsson, University of Iceland and Icelandic Meteorological Office, Reykjavik, Iceland; and M. A. Shapiro
On 9-10 November 2001 an exceptionally violent storm hit Iceland. The observed 10 min wind speed came close to 40 m/s at the north coast of the island and exceeded 50 m/s in the mountains. The airmass was exceptionally dry and depositions of sea salt were recorded several hundreds of km away from the coast. There was considerable damage and at least one house blew away.
The storm was caused by a low that deepened very rapidly as it moved to the NE along the east coast of Greenland. The low was associated with an upper level PV anomaly that intensified significantly when passing over S-Greenland.
At the high wind speeds, and with an unstable airmass at low levels, the nondimensional height of Icleand (Nh/U) is very low and the flow is far from being blocked. Yet, QuikSCAT data reveals a large and extended wake in the lee of Iceland, with well defined jets on both sides of it.
Numerical simulations reproduce a warm wake, the jets and they also reveal strong mountain waves over the east coast of Iceland.
Simulation of the same case with the topography of Greenland lowered to sea level shows no closed low to form at the east coast of Greenland, west of Iceland and there is no windstorm over Iceland.
Session 16, Downslope Windstorms
Thursday, 20 June 2002, 4:30 PM-5:30 PM
Previous paper Next paper