中文摘要：

大量观测数据的计算表明,在对流层高层和平流层低层,大气动能谱在大尺度的斜率近似为k-3,到中尺度转换为近似k-5/3,动能谱的斜率及其转折特征可作为大气运动的基本规律检验数值模式。利用这一特征对GRAPES-GFS全球中期数值预报模式产品进行了检验评估。采用0.25°分辨率GRAPES-GFS模式2013年5月的预报场,分析了模式动能谱的垂直分布及动能谱的辐散分量和旋转分量。结果表明：在对流层高层和平流层低层（225—10 hPa）,模式的动能谱曲线能较好地再现大气动能谱从大尺度过渡到中尺度的斜率转折特征,特别是在100 hPa附近动能谱的转折特征比较明显,但是动能谱斜率的绝对值较通常的观测结果（k-3和k-5/3）偏大;在大尺度范围,旋转分量在总动能谱中占优,随着波数的增大（尺度的减小）辐散分量逐渐与旋转分量相当甚至超过旋转分量。基于条件极值的思想提出一种计算转折点（拐点）的新方法,该方法能够较准确地计算出动能谱曲线拐点的位置,而且拐点位置随高度的变化与辐散和旋转分量谱交点位置随高度的变化一致。此外,还计算了辐散分量谱的斜率,发现其在中尺度范围内非常接近k-5/3,验证了其对总动能谱转折过程中的关键作用。综上,GRAPES-GFS模式能够准确地再现大气动能谱由大尺度到中尺度的斜率转折特征;与旋转分量相比,模式对动能谱辐散分量的描述更为准确,而且模式对旋转分量的较大误差导致了总动能谱的斜率绝对值偏大。

英文摘要：

In the upper troposphere and the lower stratosphere,the atmospheric kinetic energy spectrum shows a transition characteristic,from dependence at large-scale range to dependence at meso-scale range,which can be used as a basic law to assess the accuracy of numerical models.The rusults of GRAPES-GFS in May 2013 are analyzed in this paper.The accuracy of high-resolution GRAPES-GFS is estimated by computing the kinetic energy spectrum and its vertical distribution.The contributions of rotational and divergent components to the total kinetic energy spectrum are also analyzed.The results show that the slope of model kinetic energy spectrum transforms from large-scale range to meso-scale range,but the slopes both in these two ranges are steeper than that of the observation.During the large-scale range,the rotational component is primary in the total kinetic energy spectrum.But with the increasing of wavenumber（decreasing of wavelength）,the divergent component becomes comparable even excesses the rotational component.By introducing the principle of conditional extreme value,a new approach is developed to calculate the location of the slope transform that is also called as changepoint.It is demonstrated that the accuracy of this new approach is comparative with that of the Levenberg-Marquardt approach,and the former approach does not need an initial value during the calculation.By using this new approach,the changepoint and the cross of rotational and divergent components are calculated.The results show that the vertical profile of the changepoint is consistent with that of the cross.In addition,the slopes of the divergent component are analyzed.In the meso-scale range,these slopes are very close to-5/3 at all the altitudes,which implies that the divergent component is dominant in the total kinetic energy during the meso-scale range,but the rotational component is dominant during the large-scale range.The difference of their slope results in the slope change of the kinetic energy spectrum.Furthermore,for the slope of