Long-Term Observations of the Convective Boundary Layer Using Insect Radar Returns at the SGP ARM Climate Research Facility
Long-Term Observations of the Convective Boundary Layer Using Insect Radar Returns at the SGP ARM Climate Research Facility
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DOI：
10.1175/2010jcli3395.1
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发表时间：
2010-11-01
影响因子：
4.9
通讯作者：
Klein, Stephen A.
中科院分区：
文献类型：
--
作者：
Chandra, Arunchandra S.;Kollias, Pavlos;Klein, Stephen A.
介绍了美国能源部大气辐射测量计划(ARM)南大平原(SGP)气候研究设施对流边界层(CBL)湍流结构的长期研究。夏季期间占据边界层最低2公里的昆虫的多普勒速度测量被用来绘制CBL中的垂直速度分量图。观测覆盖了四个夏季时期(2004-08年)，分为多云和晴朗边界层条件。估计了垂直速度变化、偏度和质量通量的廓线，以研究在这些条件下对流边界层的白天演变。将条件采样方法应用于原始的多普勒速度数据集，以提取相关的垂直速度结构，并检验羽流的尺寸和对湍流输送的贡献。总体而言，得出的湍流统计数据与以前的飞机和激光雷达观测结果一致。这些观测对对流边界层的白天演变和云量增加在次云层湍流预算中的作用提供了独特的见解。相关结构(羽流-热流)被发现占云雷达系统解析的总湍流输送的80%以上。扩展的数据集适用于评估边界层参数和测试各种表面和云条件的大涡模拟(LESS)。
A long-term study of the turbulent structure of the convective boundary layer (CBL) at the U. S. Department of Energy Atmospheric Radiation Measurement Program (ARM) Southern Great Plains (SGP) Climate Research Facility is presented. Doppler velocity measurements from insects occupying the lowest 2 km of the boundary layer during summer months are used to map the vertical velocity component in the CBL. The observations cover four summer periods (2004-08) and are classified into cloudy and clear boundary layer conditions. Profiles of vertical velocity variance, skewness, and mass flux are estimated to study the daytime evolution of the convective boundary layer during these conditions. A conditional sampling method is applied to the original Doppler velocity dataset to extract coherent vertical velocity structures and to examine plume dimension and contribution to the turbulent transport. Overall, the derived turbulent statistics are consistent with previous aircraft and lidar observations. The observations provide unique insight into the daytime evolution of the convective boundary layer and the role of increased cloudiness in the turbulent budget of the subcloud layer. Coherent structures (plumes-thermals) are found to be responsible for more than 80% of the total turbulent transport resolved by the cloud radar system. The extended dataset is suitable for evaluating boundary layer parameterizations and testing large-eddy simulations (LESs) for a variety of surface and cloud conditions.