This study develops a statistical conditional approach to evaluate climate model performance in wind speed and direction and to project their future changes under the representative concentration pathway 8.5 scenario over inland and offshore locations across the Continental United States. The proposed conditional approach extends the scope of existing studies by characterizing the changes of the full range of the joint wind speed and direction distribution. Directional wind speed distributions are estimated using two statistical methods: a Weibull distributional regression model and a quantile regression model, both of which enforce the circular constraint to their resulting estimates of directional distributions. Projected uncertainties associated with different climate models and model internal variability are investigated and compared with the climate change signal to quantify the statistical significance of the future projections. In particular this work extends the concept of internal variability to the standard deviation and high quantiles to assess the relative magnitudes to their projected changes. The evaluation results show that the studied climate model capture both historical wind speed, wind direction, and their dependencies reasonably well over both inland and offshore locations. In the future, most of the locations show no significant changes in mean wind speeds in both winter and summer, although the changes in standard deviation and 95th-quantile show some robust changes over certain locations in winter. The proposed conditional approach enables the characterization of the directional wind speed distributions, which offers additional insights for the joint assessment of speed and direction.
翻译:这项研究开发了一种有条件的统计方法,以评价气候模型在风速和风向方面的表现,并根据具有代表性的集中途径对美国大陆大陆内陆和岸外地点的8.5假设情况预测其未来变化。拟议的有条件方法扩大了现有研究的范围,具体介绍了联合风速和方向分布的全部变化。风向速度分布使用两种统计方法估算:Weibull分布回归模型和四分回归模型,这两种方法都对由此得出的方向分布估计施加了循环限制。对不同气候模型和模型内部变异性所预测的不确定性进行了调查,并与气候变化信号进行比较,以量化未来预测的统计意义。特别是,这项工作将内部变异的概念扩大到标准偏差和高位数,以评估其预测变化的相对规模。评价结果表明,所研究的气候模型既反映了历史风速、风向方向,也反映了其在内陆和近海地点的合理依赖性。今后,大多数地点没有显示冬季和夏季的平均风速出现重大变化,尽管标准偏差的变化和某些冬季方向的拟议偏差和95度评估有助于某些冬季方向的可靠度。