THE GREENLAND LEE-LOW AND A FORECAST ERROR OF THE 8 JANUARY 2005 DENMARK WINDSTORM

Forecasts of the 8 January Denmark Windstorm are compared. In a wrong forecast, the Greenland-lee low is far to shallow, there is less outflow of cold air from west of Greenland and consequently a poor development of the upper trough that fed the windstorm. The analysis of the forecasts and an ETKF analysis support that a correct analysis of the atmosphere in the region between Iceland and Greenland would have been of importance to get a correct forecast of the windstorm over Denmark 3 days later

THE GREENLAND LEE-LOW AND A FORECAST ERROR OF THE 8 JANUARY 2005 DENMARK WINDSTORM

Forecasts of the 8 January Denmark Windstorm are compared. In a wrong forecast, the Greenland-lee low is far to shallow, there is less outflow of cold air from west of Greenland and consequently a poor development of the upper trough that fed the windstorm. The analysis of the forecasts and an ETKF analysis support that a correct analysis of the atmosphere in the region between Iceland and Greenland would have been of importance to get a correct forecast of the windstorm over Denmark 3 days later

Determination of eddy dissipation rate by Doppler lidar in Reykjavik, Iceland

Publisher's version (útgefin grein)The temporal and spatial scale of atmospheric turbulence can be highly dynamic, requiring sophisticated methods for adequate detection and monitoring with high resolution. Doppler light detection and ranging (lidar) systems have been widely used to observe and monitor wind velocity and atmospheric turbulence profiles as Doppler lidar systems can provide continuous information about wind fields. The use of lidars in the subarctic region is particularly challenging as aerosol abundance can be very low, leading to weak backscatter signals. In the present study, we analysed data collected with a Leosphere Windcube 200S lidar system stationed in Reykjavik, Iceland, to estimate the eddy dissipation rate (EDR) as an indicator of turbulence intensity. For this purpose, we retrieved radial wind velocity observations from velocity-azimuth display scans and computed the EDR based on the Kolmogorov theory. We compared different noise filter thresholds, scan strategies and calculation approaches during typical Icelandic weather conditions to assess the accuracy and the uncertainty of our EDR estimations. The developed algorithm can process raw lidar observations, retrieve EDR and determine the qualitative distribution of the EDR. The processed lidar observations suggest that lidar observations can be of high importance for potential end-users, for example air traffic controllers and aviation safety experts. The work is an essential step towards enhanced aviation safety in Iceland where aerosol concentration is in general low and severe turbulence occurs regularly.This study was partly funded by Isavia, the Icelandic airport and air navigation service provider."Peer Reviewed

The Wind Energy Potential of Iceland

AbstractDownscaling simulations performed with the Weather Research and Forecasting (WRF) model were used to determine the large-scale wind energy potential of Iceland. Local wind speed distributions are represented by Weibull statistics. The shape parameter across Iceland varies between 1.2 and 3.6, with the lowest values indicative of near-exponential distributions at sheltered locations, and the highest values indicative of normal distributions at exposed locations in winter. Compared with summer, average power density in winter is increased throughout Iceland by a factor of 2.0–5.5. In any season, there are also considerable spatial differences in average wind power density. Relative to the average value within 10 km of the coast, power density across Iceland varies between 50 and 250%, excluding glaciers, or between 300 and 1500 W m−2 at 50 m above ground level in winter. At intermediate elevations of 500–1000 m above mean sea level, power density is independent of the distance to the coast. In addition to seasonal and spatial variability, differences in average wind speed and power density also exist for different wind directions. Along the coast in winter, power density of onshore winds is higher by 100–700 W m−2 than that of offshore winds. Based on these results, 14 test sites were selected for more detailed analyses using the Wind Atlas Analysis and Application Program (WAsP)

Prototype of multi-hazard early warning from EUNADICS-AV systems to trigger model forecasts of European airspace

info:eu-repo/semantics/nonPublishe