中文摘要：

下击暴流是雷暴天气中沿地面传播的一种极具突发性和破坏性的一种强风,对建筑结构的破坏性极强,因此建立准确可靠的下击暴流风速模型对于研究建筑结构在下击暴流作用下的动力响应并减少灾害发生是至关重要的。本文采用随时间变化的向量自回归模型（简称TVAR模型）建立下击暴流的风速模型。采用基函数方法识别TVAR模型参数,即将TVAR模型参数表示为加权时间函数的线性组合。联合使用正向估计和后向估计器估计TVAR模型中的随时间变化参数,计算得到下击暴流随时间变化功率谱密度。模拟得到了下击暴流风速、功率谱密度、相干函数等重要参数。结果表明本文提出的TVAR模型可以准确模拟下击暴流风速场,且计算效率得到了进一步提高。本文提出的TVAR模型为准确进行下击暴流模拟或建立经验模型提供了可靠的方法。

英文摘要：

Thunderstorm is a sudden strong wind along ground surface occurring in thunderstorm weather, which has a destructive effects on structures. It is crucial to model thunderstorm accurately for studying the dynamic re- sponses of structures. Vector time-varying autoregressive （TVAR） model is used to model the wind velocities of thunderstorms. Basic function method is employed to identify the parameters of TVAR model, that is, the parame- ters of TVAR model are expressed as a linear combination of weighted time functions. Forward and backward esti- mators are combined to estimate the time varying parameters in TVAR model, and the time varying PSD of thunder- storu~s is computed. Wind velocities, PSD and coherence functions of thunderstorms are obtained by the proposed TVAR model. The results show that the wind velocity field can be accurately simulated by using TVAR model, and the computing efficiency is improved greatly. TVAR model proposed provides a reliable method for accurately model thunderstorms or establish the empirical model.