Real-Time Characterization of Aerosol Particle Composition above the Urban Canopy in Beijing: Insights into the Interactions between the Atmospheric Boundary Layer and Aerosol Chemistry

2015 ◽  
Vol 49 (19) ◽  
pp. 11340-11347 ◽  
Author(s):  
Yele Sun ◽  
Wei Du ◽  
Qingqing Wang ◽  
Qi Zhang ◽  
Chen Chen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Real Time ◽  
Aerosol Particle ◽  
Urban Canopy ◽  
Aerosol Chemistry ◽  
Particle Composition

Real‐time characterization of aerosol particle composition, sources and influences of increased ventilation and humidity in an office

Indoor Air ◽  
2021 ◽  
Author(s):  
Junyao Li ◽  
Weiqi Xu ◽  
Zhijie Li ◽  
Minzheng Duan ◽  
Bin Ouyang ◽  
...  
Keyword(s):  
Real Time ◽  
Aerosol Particle ◽  
Particle Composition

scholarly journals High-Resolution Observations of Insects in the Atmospheric Boundary Layer

2008 ◽  
Vol 25 (12) ◽  
pp. 2176-2187 ◽  
Author(s):  
Robert F. Contreras ◽  
Stephen J. Frasier
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Cross Sections ◽  
Continuous Monitoring ◽  
Rayleigh Scattering ◽  
Continuous Wave ◽  
Time Of Day ◽  
Fmcw Radar ◽  
Radar Cross Sections

Abstract High spatial and temporal resolution S-band radar observations of insects in the atmospheric boundary layer (ABL) are described. The observations were acquired with a frequency-modulated continuous-wave (FMCW) radar during the 2002 International H20 Project (IHOP_2002) held in Oklahoma in the months of May and June 2002. During the observational period the boundary layer was convective with a few periods of rain. Rayleigh scattering from particulate scatterers (i.e., insects) dominates the return; however, Bragg scattering from refractive index turbulence is also significant, especially at the top of the afternoon boundary layer. There is a strong diurnal signal in the insect backscatter: minima in the morning and at dusk and maxima at night and midafternoon. Insect number densities and radar cross sections (RCSs) are calculated. The RCS values range from less than 10−12 m2 to greater than 10−7 m2 and likewise have a strong diurnal signal. These are converted to equivalent reflectivity measurements that would be reported by typical meteorological radars. The majority of reflectivity measurements from particulate scatterers ranges from −30 to −5 dBZ; however, intense point scatterers (>10 dBZ) are occasionally present. The results show that although insects provide useful targets for characterization of the clear-air ABL, the requirements for continuous monitoring of the boundary layer are specific to time of day and range from −20 dBZ in the morning to −10 to −5 dBZ in the afternoon and nocturnal boundary layer (NBL).

Atmospheric Boundary Layer Dynamics Evaluation Using Piezo-Resistive Technology for Unpowered Areal Vehicles

2020 ◽  
Vol 2 (1) ◽  
pp. 1-19
Author(s):  
Alexander Shamliev ◽  
Peter Mitrouchev ◽  
Maya Dimitrova
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Real Time ◽  
Time Measurement ◽  
Flight Time ◽  
Real Time Measurement ◽  
Aerial Vehicles ◽  
Boundary Layer Dynamics ◽  
Soaring Flight ◽  
Time Evaluation

The paper presents a method for real-time observing of the convectional processes in the atmosphere boundary layer. The essence of the method is in providing real-time measurement of temperature, humidity, and pressure during the flight of a glider (soaring flight). Based on these measurements, a real-time evaluation of the atmosphere dynamics is presented. Measurements are taken during soaring flight of the glider and during the flight of a remotely controlled quadrocopter. Additionally, a method for atmosphere thermal identification by the measured parameters is introduced. The main application areas of this work are in unpowered flights, as well as in extending the flight time and distance of powered aerial vehicles. Moreover, the paper can be useful in research and observation of the lowest portion of the atmosphere and micro-scaled atmosphere dynamics evaluation.

Resolving urban canopy flows: Scales, turbulence and boundary conditions in obstacle-resolving numerical models

2021 ◽  
Author(s):  
Benedikt Seitzer ◽  
Bernd Leitl ◽  
Frank Harms
Keyword(s):  
Boundary Layer ◽  
Boundary Conditions ◽  
Atmospheric Boundary Layer ◽  
Similarity Theory ◽  
Urban Canopy ◽  
Large Eddy Simulations ◽  
Roughness Sublayer ◽  
Boundary Layer Meteorol ◽  
Large Eddy ◽  
Near Wall

<p>Large-eddy simulations are increasingly used for studying the atmospheric boundary layer. With increasing computational resources even obstacle-resolving Large-eddy simulations became possible and will be used in urban climate studies more frequently. In these applications, grid sizes are in the order of a few meters. Whereas major urban structures can be resolved in general, details like aerodynamically rough surface structures can not be resolved explicitly. Based on the original fields of application, boundary conditions in Large-eddy simulations were initially formulated for surfaces of homogeneous roughness and for wall-distances much larger than the roughness sublayer height (Hultmark et al., 2013). The height of the roughness sublayer depends on the size of small-scale obstacles present on the surface exposed to the flow (Raupach et al., 1991). Typically, boundary conditions are evaluated between the surface and the first grid level. Thus, grid resolution in obstacle-resolved Large-Eddy simulations should also be a question of scales and therefore has to be chosen carefully (Basu and Lacser, 2017; Maronga et al., 2020). <br />In several wind tunnel experiments presented here, we measured the near-wall influence of differently scaled and shaped objects on a flow and its turbulence characteristics. Experimental setups were replicated numerically using the PALM model (Maronga et al. 2019). In a first, more generic experiment, the flow over horizontally homogeneous surfaces of different roughness was investigated. In a second experiment, the spatial separation of the turbulence scales was investigated in a more complex flow case. These experiments lead to considerations on model grid sizes in urban type Large-eddy simulations. The limitations of interpreting simulation results within the urban canopy layer are highlighted. There is an urgent need to reconsider how near-wall results of urban large-eddy simulations are generated and interpreted in the context of practical applications like flow and transport modelling in urban canopies. <br /><br /><em><strong>References</strong></em><br /><em>Basu, S. and Lacser, A. (2017). A Cautionary Note on the Use of Monin–Obukhov Similarity Theory in Very High-Resolution Large-Eddy Simulations. Boundary-Layer Meteorol, 163(2):351–355.</em></p> <p><em>Hultmark, M., Calaf, M., and Parlange, M. B. (2013). A new wall shearstress model for atmospheric boundary layer simulations. J Atmos Sci,70(11):3460–3470.</em></p> <p><em>Maronga, B., et al. (2020). Overview of the PALM model system 6.0. Geosci Model Dev Discussions, 06(June):1–63.</em></p> <p><em>Maronga, B., Knigge, C., and Raasch, S. (2020). An Improved Surface Boundary Condition for Large-Eddy Simulations Based on Monin–Obukhov Similarity Theory: Evaluation and Consequences forGrid Convergence in Neutral and Stable Conditions. Boundary-Layer Meteorol, 174(2):297–325.</em></p> <p><em>Raupach, M. R., Antonia, R. A., and Rajagopalan, S. (1991). Rough-wall turbulent boundary layers. Appl Mech Rev, 44(1):1–25</em></p>

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