关键词: WERAS/CMA, MM5/FDDA/CALMET, 狭管风区, 湖陆风, 风场预报

Abstract: To objectively evaluate the abilities of simulating/forecasting wind energy resource by the method of objective analysis in WERAS/CMA system (hereafter referred to as CTL scheme) and objective analysis replaced by four-dimensional data assimilation (FDDA) at complex land surface patter and rough terrain, such as Alashankou and Dabancheng-Xiaocaohu wind area which is influenced by both the effect of narrow pipe and lake-land breeze, the two schemes are analyzed and contrasted each other based on 12UTC NCEP reanalysis data and WMO conventional observation data issued by CMACAST during 2009 (July and October) and 2010 (January and April). The results indicate that: (1) For complex region, both of them are all reliable in detailed assessing and forecasting wind energy resources showing that the average relative error at least reduced by 10% compared to the precious method which utilized meso-scale model only. (2) But on the whole, they don't only have a very similar defect in describing the profile characteristic of average wind speed/wind direction frequency at the areas under the control of multiple micro-scale circulation, but also show greater error at 70 m than that at 30, 50 m and 100 m. (3) At about 70 m level, the predictive mean relative error for the ≤5 m·s^-1 is up to 60%-130%, for the >5 m·s^-1 is less than 15%. And the error is greater apparently at the areas of lake-land breeze effect and it is concerned with the changing of season. (4) At about 70 m, all of them can simulate climate background of different wind speed threshold value well, exhibiting that the threat scores for the 5-15 m·s^-1 intervals is up to 0.6-0.7 at Dabancheng wind area, and for the ≤5 m·s^-1is 0.6-0.7 at Alashankou and 0.9 or so at Xiaocaohu wind area. However, the threat scores for the ≤5 m·s^-1 interval is only 0.3-0.4 at Dabancheng wind area. (5) For all wind regions, the threat scores of the two schemes at about 70m are only 0.4-0.6 in predicting strong wind of above 15 m·s^-1 when the wind turbine generator need to stop or take some safeguard procedures. (6) Under the control of various local multi-scale circulations, for different heights of the same mask, the FDDA scheme does not seem to always provide better forecasting effect than the CTL scheme except at about 70 m height at which FDDA scheme is slightly better the CTL, even at the same wind area or different seasons, the forecasting effects are different from each other among various masks. So the physical mechanism why exists this kind of strange feature should be further illustrate in the future.

Key words: WERAS/CMA, MM5/FDDA/CALMET, funneling wind area, lake-land breeze, wind field forecasting