Knowledge Resource Center for Ecological Environment in Arid Area
| 雷暴系统影响下的黄土高原塬区大气边界层特征研究 | |
| 其他题名 | Study on characteristics of atmospheric boundary layer over the loess plateau under the influence of thunderstorm |
| 张新科 | |
| 出版年 | 2017 |
| 学位类型 | 硕士 |
| 导师 | 陈晋北 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 雷暴等强对流天气系统的发生发展主要是由气压场和天气系统环流特征所决定的，而大气边界层过程通过输送热量和水汽等也会影响强对流系统内部层结状况及能量分布，从而促进或抑制系统的发展，甚至在强对流系统发展产生雷电、冰雹等过程中也起到重要作用。因此揭示雷暴等强对流天气系统与大气边界层过程相互影响机理是更加准确预报雷暴等灾害性天气亟待解决的问题。黄土高原是我国东部季风区和西部干旱区的过渡带，为典型的大陆性季风气候。由于该地区季风气候极不均匀造成全年总雨量较少，65%的雨水集中在夏季；加之该区域黄土的土质疏松，因此导致极为严重的水土流失，形成了“沟壑纵横”的黄土地貌。甘肃省平凉市正位于黄土高原腹地，受季风影响和地形抬升效应，极易发生雷暴、冰雹、暴雨等强对流灾害天气，给当地人民生命财产安全造成严重危害。因此本文利用中国科学院平凉陆面过程与灾害天气观测研究站2012~2013年夏季雷达、近地面层梯度、涡动相关系统观测资料，分类选取不同强度、不同尺度和结构特征的雷暴系统，针对其过境前后近地面层气象要素变化特征，研究近地层湍流结构的变化，及其对感热和潜热输送的影响；并利用湍流统计理论、谱分析方法和小波分析方法研究了雷暴系统过境期间速度和温度湍流的不同尺度涡旋能谱分布特征。以揭示雷暴等强对流天气过程的尺度与近地面层湍流尺度的相关特征，为陆面过程与天气系统相互作用的参数化方案提供奠定实验基础。通过大量的对比分析和研究，本文得到如下主要研究结果：（1）每年5月中旬至9月底，受西风带和副热带高压的控制以及山谷沟壑地形的影响，平凉地区大气边界层中通常出现较强的辐散和辐合作用；这不但使观测区大气边界层能发展到一个较高高度，而且造成较强的热量和水汽输送。（2）特别在雷暴系统过境前约3~5小时，近地层中的辐散和辐合作用进一步加强，出现明显的上升气流，水平风速逐渐增大，气压升高，湿度明显减小。雷暴系统影响期间，近地层水平风速急剧增大，风向突变，温度迅速降低，受雷暴后部下沉辐散区的影响，上升气流迅速变为下沉气流，最大下沉速度可以达到-0.8m/s以上，这比一般晴天时垂直速度大一个量级以上；且近地层摩擦速度、动量通量和湍流动能急剧增大，感热通量和潜热通量骤变。（3）速度谱分析结果显示，在一般晴天条件下，但在惯性副区，三维风速湍流谱都满足-2/3次标度律；而在低频区（小于0.01Hz）湍流谱能开始减小，只是局地环流尺度涡旋的谱能有所增大。雷暴影响期间，惯性副区三维风速湍流谱仍然满足-2/3次标度律，与晴天时结果相似，只是湍流谱能量相较于晴天明显增大；但在低频区（小于0.01Hz），三维风速能谱曲线急剧抬升，大尺度低频涡旋能量迅速增加，此时速度湍流谱能比晴天时大1~2个量级，而且u、v谱能量相较于w谱能量增加更为明显。然而雷暴影响期间温度湍流谱结构与速度谱有较大不同，由于雷暴过境期间辐合辐散效应以及区域较强的切变造成温度谱在高频区有明显的上翘现象。（4）湍流通量的Ogive函数分析显示，在雷暴系统影响下大尺度低频涡旋对感热通量和潜热通量的输送量显著增加，即大尺度低频涡旋对湍流通量的贡献是主要的。垂直速度和温度相关系数的Ogive函数指出，受雷暴影响期间，高频（>0.003Hz）小尺度涡旋的垂直速度与温度和湿度相关系数较小，甚至相关系数发生正负波动。这意味着平流输送对感热通量和潜热通量产生了影响。但低频（<0.003Hz）大尺度涡旋的垂直速度与温度和湿度相关系数较大，它也最终决定着通量的方向。这意味着大尺度辐散辐合运动主导了感热通量和潜热通量的输送。同时小波分析结果显示，雷暴系统影响期间，近地层湍流运动具有明显的多尺度结构，而且小波方差峰值对应的主振荡尺度与雷暴单体系统特征尺度相当。 |
| 英文摘要 | Formation and development of strong convection weather system, such as thunderstorm, is determined by the pressure field and the background of weather system, the atmospheric boundary layer process not only transport the heat and water vapor from the surface to promote or inhibit the development of the convective systems，but even plays an important role in the development of lightning and hail caused. Therefore, it is revealed that the mechanism of the interaction between the severe convective weather system and the atmospheric boundary layer that is a problem to be solved urgently in the severe weather forecasting. The Loess Plateau，which is in the eastern part of “the Belt and Road”, is the transitional zone between the eastern monsoon and the western arid region. The climate of Loess Plateau is a typical continental monsoon climate. In the region, the annual total rainfall is less and 65% of the rain is concentrated in the summer because of effect of the monsoon climate. In addition, the loose soil in the area leads to extremely serious soil erosion, forming the loess landform of the "gully aspect". Pingliang City, located in the hinterland of the Loess Plateau, extremely prone to occur thunderstorms, hail, heavy rain or other strong convective weather because of effect of monsoon and terrain. It seriously affected people’s life and productions in this zone.In this thesis, based on the observation data of summer from 2012 to 2013 at the Pingliang Land Surface and Severe Weather Research Stationthe, the atmospheric boundary layer characteristics during strong convection system with different scales and different strength were analyzed. The methods used in the research process included turbulence statistical theory, spectral analysis d and wavelet analysis. The purpose of the thesis is to provide near-surface layer thunderstorm’s prediction parameters and experimental basis of numerical simulation parameterization for the Loess Plateau and other areas by revealing the characteristics of the convective weather system and the near-surface layer turbulence scales.Through a large number of comparative analysis and research, the main contents and results are as follow:(1) Pingliang’s area has a strong divergence and convergence in the atmospheric boundary layer from after mid-May to the end of September because of the influence of the valley gully terrain. It is not only makes the atmospheric boundary Layer to develop to a larger height, but also causes strong heat and water vapor transport. (2) Before the thunderstorm occurring 3 to 5 hours, the divergence and convergence is strengthen and there is a clear upward airflow. When suffering thunderstorms, the horizontal wind speed, air pressure were significantly increased but humidity was significantly reduced. At the end of the thunderstorm, the updraft quickly becomes the downdraft, the maximum velocity can reach -0.8m/s, which is almost 1 to 2 orders of magnitude greater than normal. At the same time, there were strong temperature shear and the horizontal wind shear between the thunderstorm and the surrounding environment.(3) The friction velocity, the momentum flux and turbulence kinetic energy increased sharply and the sensible heat flux and latent heat flux change abruptly during the influence of the strong convective system. The results of turbulence spectrum’s analysis showed: during normal conditions, the spectral energy of the large-scale low-frequency vortex in less than 0.01 Hz begins to decrease but the spectral energy of the local circulation scale vortex is increased at 14 height above ground. However, when the thunderstorm passed the station, the spectrum energy of velocity turbulence can be 1 to 2 orders of magnitude larger than normal conditions and energy of large-scale low-frequency vortex increased rapidly. In the low frequency region (less than 0.01 Hz), the u, v, w energy spectrum curve is sharply uplifted, and the large scale vortex dominates the turbulence spectrum. And the u, v spectrum is more pronounced than that of the w spectrum. However, in the turbulent inertial subareas, the wind velocity turbulence spectra of the u, v and w winds satisfy the -2 / 3th scale law, which is similar to that of the sunny day, but the turbulence spectrum is obviously increased compared with the sunny day. However, the turbulence Spectral structure and velocity spectrum are quite different, during the thunderstorm transit convergence divergence effect and the regional strong shear caused by the temperature spectrum in the high frequency area has obvious upturned phenomenon.(4) The results of Ogive function analysis of the turbulent flux showed that the amount of heat flux and latent heat flux is significantly increased because the energe of large-scale low-frequency vortex during the thunderstorm. That is to say, the contribution of the large-scale low-frequency vortex to the turbulent flux plays the main role. In the high frequency region (> 0.003Hz), the correlation between the vertical velocity and the temperature, humidity is small, and even the correlation coefficient is positive and negative fluctuation. This means that advection conveys heat and moisture that affect sensible heat flux and latent heat flux. However, in the low frequency region (<0.003 Hz), the vertical velocity of the large scale vortex is larger with the temperature and the correlation coefficient, and it also determines the direction of the flux. This means that large-scale divergent convergence exercises dominate the sensible heat flux and latent heat flux. The results of wavelet analysis show that the near - stratospheric turbulence has obvious multi - scale structure during the influence of thunderstorm system, and the corresponding dimension of wavelet variance is equivalent to the characteristic scale of thunderstorm system. |
| 中文关键词 | 关键词：雷暴强对流系统 ; 湍流涡旋 ; 近地面层 ; 小波分析 ; Ogive函数 |
| 英文关键词 | Key Words: thunderstorm strong convection system turbulent vortex near surface layer wavelet analysis Ogive function |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 气象学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287975 |
| 推荐引用方式 GB/T 7714 | 张新科. 雷暴系统影响下的黄土高原塬区大气边界层特征研究[D]. 中国科学院大学,2017. |
| 条目包含的文件 | 条目无相关文件。 | |||||
| 个性服务 |
| 推荐该条目 |
| 保存到收藏夹 |
| 导出为Endnote文件 |
| 谷歌学术 |
| 谷歌学术中相似的文章 |
| [张新科]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [张新科]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [张新科]的文章 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
