VERIFICATION OF THE OPERATIONAL 10 M WIND FORECAST OBTAINED WITH THE ALADIN MESOSCALE NUMERICAL WEATHER PREDICTION MODEL

摘要

This paper presents the results of the verification of operational 10 m wind forecast obtained with the ALADIN mesoscale numerical weather prediction model. In the period 2010-2012 ALADIN/ALARO 8 km forecasts were initialized daily at 00 UTC and driven with the ARPEGE global model forecasts through the 72-hourly forecasting range. Obtained forecasts were further refined to 2 km grid spacing, using the simplified and cost-effective dynamical adaptation method (ALADIN/DADA 2 km forecasts). Since the primary objective of thisstudy is to assess the efficiency of wind forecast in regions of complex terrain as well as high wind energy potential, eight stations from different wind climate regions of the eastern Adriatic coast were selected to perform the verification procedure. Based on variety of statistical and spectral scores, it is suggested that the wind forecast generally improves with the increase of horizontal resolution. At bora dominated stations, the multiplicative mean systematic error isreduced by more than 50%. The largest portion of root-mean square errors can be attributed to dispersion or phase errors at majority of stations and their contribution increases with model horizontal resolution. Spectral analysis in the wavenumber domain suggests that the slope of kinetic energy spectra of both models decreases from k-3 in the upper troposphere towards ~ k-5/3 near the surface (corresponding to orography spectra) and shows minor seasonal variability. Spectral decomposition of measured and modeled data in the frequency domain indicates a significant improvement in simulating the primary and secondary maximum of spectral power(related to synoptic and diurnal motions) by using the ALADIN/DADA 2 km model, especially for the cross-mountain wind component mostly related to strong and gusty bora flows. Finally, the common feature of both models is a significant underestimation of motions atscales below semi-diurnal, which is a result of their absence in initial conditions and of limited model ability to represent small-scale processes.