The Finnish Wind Atlas was prepared applying the mesoscale model AROME with 2.5 km horizontal resolution and the diagnostic downscaling method Wind Atlas Analysis and Application Programme (WAsP) with 250 m resolution. The latter was applied for areas most favourable for wind power production: a 30 km wide coastal/offshore zone, highlands, large lakes and large fields. The methodology included several novel aspects: (i) a climatologically representative period of real 48 months during 1989-2007 was simulated with the mesoscale model; (ii) in addition, the windiest and calmest months were simulated; (iii) the results were calculated separately for each month and for sectors 30°wide; (iv) the WAsP calculations were based on the mesoscale model outputs; (v) in addition to point measurements, also radar wind data were applied for the validation of the mesoscale model results; (vi) the parameterization method for gust factor was extended to be applicable at higher altitudes; and (vii) the dissemination of the Wind Atlas was based on new technical solutions. The AROME results were calculated for the heights of 50, 75, 100, 125, 150, 200, 300 and 400 m, and the WAsP results for the heights of 50, 75, 100, 125 and 150 m. In addition to the wind speed, the results included the values of the Weibull distribution parameters, the gust factor, wind power content and the potential power production, which was calculated for three turbine sizes. The Wind Atlas data are available for each grid point and can be downloaded free of charge from dynamic maps at www.windatlas.fi. Production of the Finnish Wind Atlas B. Tammelin et al.Accordingly, a strong need arose for a more accurate wind atlas. In Finland, the size of the country, its complex terrain and large seasonal differences generate strong demands for a wind atlas. The complexity of the terrain is not so much related to orography but to the complex shape of the almost flat coastline and archipelago, which generates a need for very high spatial resolution. Further, the differences in wind conditions between seasons are particularly large because in winter, the sea and lakes are frozen and the ground is covered by snow, which changes the surface roughness and stabilizes the atmospheric boundary layer (ABL). Stable stratification favours the generation of low-level jets. 4 In winter, wind power plants are also subject to ice accretion. The production of a new Wind Atlas for Finland has also been motivated by the need to evaluate the possible effects of climate change on wind conditions. In 2008, the Ministry of Labour and Economics released an international tender for production of the new Finnish Wind Atlas. The tender was won by the Finnish Meteorological Institute (FMI), with Risø DTU and Vaisala Ltd as subcontractors. The project started 1 June 2008, and the wind atlas was released 25 November 2009 (www.windatlas.fi).Many national wind atlases have recently been produced applying numerical weather prediction (NWP) models. In an ideal approach, all possible weather condition...
In this study we have examined how the anticipated anthropogenic climate change will affect the heating power demand of buildings, hydropower production, the climatological potential of peat production, bioenergy, and wind energy. The study concentrates on conditions in Finland and the future period studied was 2021-2050. The future climate conditions were primarily taken from simulations by the Hadley Centre's global climate model, HadCM3. According to the climate scenarios used in this study, the heating energy demand for the period 2021-2050 will decrease on average by some 10 % from the period 1961-1990. At the same time hydropower production will increase by 7-11 %, the climatological potential of peat production by 17-24 %, the climatological potential of biomass (mainly wood) by 10-15 % and the climatological potential of wind power by 2-10 %. These results must still be considered as preliminary, mainly because there are still large uncertainties related to the estimation of the magnitude of climate change.
The wind power potential around Pyhätunturi Fell in northern Finland is calculated with WAsP and the Karlsruhe Atmospheric Mesoscale Model (KAMM) using a climatology of the geostrophic wind from the global reanalysis of NCEP/NCAR. The importance of roughness variations between summer and winter due to snow cover and of strong, low‐level inversions during winter is investigated. At the position of a telemast on the fell the changing roughness led to an increase in the predicted wind power density of only 1% at 61 m. However, frequent inversions in winter have a major influence on the wind potential on the fell areas. Accounting for them increased the predicted wind power density by 10%–16%, giving better agreement with the observations. As expected, the wind in the plains is reduced during conditions with inversions. The simulations with KAMM were performed for a grid map with a resolution of 350 m. This is too rough to resolve the steep slopes of Pyhätunturi Fell. Therefore the predicted wind speed on the summit is underestimated by up to 15% depending on the wind direction. Copyright © 1999 John Wiley & Sons, Ltd.
The suitability of the computer model MM5 for predicting wind speed, and hence wind energy, is investigated by performing simulations for different geographical regions. The focus is on wind speed in the lowest 200 m of the planetary boundary layer (PBL). The dependency of the simulated wind speed on PBL parameterization and atmospheric stability is studied. The smallest deviation between measured and simulated wind speed, averaged over a three-day period, is 1% and occurs for an off-shore simulation with unstable stratification. The largest deviations of 31% and 20% occur with orographically structured terrain, stable stratification and weak synoptic forcing. The results suggest that unstable conditions are simulated with better accuracy by MM5. Changes of the PBL scheme cause wind speed variations between 9% and 40% of the average wind speed. None of the PBL schemes is clearly the best and their performance can strongly vary for different conditions. Nevertheless, the Mellor-Yamada-Janjic (ETA) and the Blackadar PBL parameterization (BLK) schemes seem to be the most suitable schemes for wind energy applications. Additionally, MM5 was successfully adapted for idealised, stationary simulations in order to calculate a wind-climatology for Sardinia using a statistical-dynamical downscaling approach.
This paper describes research in progress, with the aim of allowing other interested individuals and organisations to relate to the work. Communications are welcome. The project ‘WindEng’, (Wind energy assessment studies and wind engineering) studies wind characteristics in different European environments so the design of wind turbines and wind farms can be improved. This is a European ‘training-through-research’ network, see www.WindEng.net , funded within the EU FP5 “Improving Human Potential” programme, “Research Training Network” activity. The Network started in September 2002 for young scientists and experienced researchers to work together on a common project. An underlying purpose is to exchange experiences and personal contacts collaboratively to strengthen academic, research and private organisations.
Precipitation and evaporation budgets over the Baltic Sea were studied in a concerted project called PEP in BALTEX (Pilot study of Evaporation and Precipitation in the Baltic Sea), combining extensive field measurements and modelling efforts. Eddy-correlation-measurements of turbulent heat flux were made on a semi-continuous basis for a 12 month period at four well-exposed coastal sites in the Baltic Proper (the main basin of the Baltic Sea). Precipitation was measured at land-based sites with standard gauges and on four merchant ships travelling between Germany and Finland with the aid of specially designed ship rain gauges (SRGs). The evaporation and precipitation regime of the Baltic Sea was modelled for a 12 month period by applying a wide range of numerical models: the operational atmospheric High Resolution Limited Area Model (HIRLAM, Swedish and Finnish versions), the German atmospheric REgionalscale MOdel, REMO, the operational German Europe Model (only precipitation), the oceanographic model PROBE-Baltic, and two models that use interpolation of ground-based data, the Swedish MESAN model of SMHI and a German model of IFM-GEOMAR Kiel. Modelled precipitation was compared with SRG measurements on board the ships. A reasonable correlation was obtained, but the regional-scale models and MESAN gave some 20% higher precipitation over the sea than is measured. Bulk parameterisation schemes for evaporation were evaluated against measurements. A constant value of C HN and C EN with wind speed, underestimated large fluxes of both sensible and latent heat flux. The limited area models do not resolve the influence of the height of the marine boundary layer in coastal zones and the entrainment (on the surface fluxes), which may explain the observed low correlations between modelled and measured latent heat fluxes. Estimates of evaporation, E, and precipitation, P, for the entire Baltic Proper were made with several models for a 12 month period. While the annual variation was well represented by all predictions, there are still important differences in the annual means. Evaporation ranges from 509 to 625 mm year À1 and precipitation between 624 and 805 mm year À1 for this particular 12 month period. Taking the results of model verification from *Corresponding author. the present study into account, the best estimate of P-E is about 100 AE 50 mm for this particular 12 month period. But the annual mean of P-E varies considerably from year to year. This is reflected in simulations with the PROBE-Baltic model for an 18 year period, which gave 95 mm year À1 for the 12 month period studied here and 32 mm year À1 as an average for 18 years.
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