期刊
BOUNDARY-LAYER METEOROLOGY
卷 172, 期 1, 页码 45-65出版社
SPRINGER
DOI: 10.1007/s10546-019-00431-w
关键词
Flux similarity; Long-term measurements; Quadrant analysis; Transport and transfer efficiency; Urban boundary layer
资金
- project Urban Climate Study of Bucharest [IZERZ0_142160]
- Swiss National Science Foundation (SNF) [IZERZ0_142160] Funding Source: Swiss National Science Foundation (SNF)
Turbulence characteristics in the urban boundary layer of a mid-latitude European city are investigated using a quadrant analysis of more than 12years of eddy-covariance measurements at 39m above street level. To describe the ongoing turbulent-exchange processes, particularly the properties of ejection and sweep events, presented here are the transfer efficiency and the similarity of momentum, heat, CO2 and H2O fluxes. In addition, an event-detection algorithm is applied to derive information on the importance of organized structures for the turbulent exchange, finding that momentum and heat fluxes are primarily controlled by atmospheric stability, whereas CO2 and H2O fluxes are more affected by the presence of active sources of the corresponding scalars (e.g. traffic for CO2 fluxes). The transfer efficiencies of momentum and heat can thus be modelled accurately, but the prediction for CO2 and H2O fluxes fails because of scalar dissimilarity. Generally, ejections are more important under buoyancy-driven unstable conditions and responsible for large structures, and sweeps are more characteristic of stable cases and smaller structures. The quadrant statistics enable the identification of scales between a hole-size factor of 10 and 20 where turbulent exchange is especially efficient and almost solely takes place by ejection-sweep cycles. This information is used to apply an event-detection algorithm, which quantifies flux fractions of such reoccurring structures to be around 0.5-0.8, with the time fraction being usually around 0.1.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据