强天气过程中近地面层风速的非线性动力学特征

强天气过程中大气边界层不同尺度运动之间存在强烈的相互作用,这种相互作用使得近地层风速的变化表现出很强的非线性,风速的非线性特征可以用近代非线性物理中奇异性、大偏差和多重分形等特征量来刻划.作者研究了两次沙尘暴和一次冷锋时期超声风温仪观测资料的这些特征.4组资料奇异指数的概率分布基本一致,只有最强的奇异性存在差异.但最大风速的奇异性并不是最强的.风速的大偏差特征表明,不同时间长度相同的风速时间序列中出现某种极值的概率几乎不变,而大偏差谱能反映不同天气系统影响的差异,天气系统越强,越能维持涡旋运动规律不变.

Nonlinear Dynamics of Wind in Surface Layer During Violent Synoptic Process

There are strong interactions between motions of various scales during violent synoptic processes,resulting in great nonlinearity of wind,which can be characterized by such as singularity,large deviation,multifractal,and so on.Data measured by ultrasonic anemometer during two dust storms and one cold front are used.Probability distributions of four sets of singularity exponents are almost the same except some strongest singularity exponents.However,singularity of the largest wind fluctuations is not the strongest.Large deviation characteristics of wind indicate that there are almost the same probabilities for some extrema occuring during the periods of the same length,while large deviation spectra reflect the difference of different weather synoptic system.The more strong weather synoptic system,eddy motions persist more long.