London air pollution climatology: Indirect evidence for urban boundary layer height and wind speed enhancement

2008 ◽  
Vol 42 (20) ◽  
pp. 4932-4947 ◽  
Author(s):  
Matthew Rigby ◽  
Ralf Toumi
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Wind Speed ◽  
Indirect Evidence ◽  
Urban Boundary Layer ◽  
Layer Height ◽  
Boundary Layer Height

scholarly journals Tracking atmospheric boundary layer in tehran using combined lidar remote sensing and ground base measurements

2018 ◽  
Vol 176 ◽  
pp. 06011 ◽  
Author(s):  
Hossein Panahifar ◽  
Hamid Khalesifard
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Air Pollution ◽  
Wind Speed ◽  
Atmospheric Boundary Layer ◽  
Vertical Structure ◽  
Temperature Inversion ◽  
Meteorological Model ◽  
Layer Height ◽  
Boundary Layer Height

The vertical structure of the atmospheric boundary layer (ABL) has been studied by use of a depolarized LiDAR over Tehran, Iran. The boundary layer height (BLH) remains under 1km, and its retrieval from LiDAR have been compared with sonding measurements and meteorological model outputs. It is also shown that the wind speed and direction as well as topography lead to the persistence of air pollution in Tehran. The situation aggravate in fall and winter due to temperature inversion.

scholarly journals Technical note: Boundary layer height determination from Lidar for improving air pollution episode modelling: development of new algorithm and evaluation

2017 ◽  
Author(s):  
Ting Yang ◽  
Zifa Wang ◽  
Wei Zhang ◽  
Alex Gbaguidi ◽  
Nubuo Sugimoto ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
High Performance ◽  
Accurate Determination ◽  
Technical Note ◽  
Strong Increase ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Retrieval Algorithms ◽  
The Impact

Abstract. Predicting air pollution events in low atmosphere over megacities requires thorough understanding of the tropospheric dynamic and chemical processes, involving notably, continuous and accurate determination of the boundary layer height (BLH). Through intensive observations experimented over Beijing (China), and an exhaustive evaluation existing algorithms applied to the BLH determination, persistent critical limitations are noticed, in particular over polluted episodes. Basically, under weak thermal convection with high aerosol loading, none of the retrieval algorithms is able to fully capture the diurnal cycle of the BLH due to pollutant insufficient vertical mixing in the boundary layer associated with the impact of gravity waves on the tropospheric structure. Subsequently, a new approach based on gravity wave theory (the cubic root gradient method: CRGM), is developed to overcome such weakness and accurately reproduce the fluctuations of the BLH under various atmospheric pollution conditions. Comprehensive evaluation of CRGM highlights its high performance in determining BLH from Lidar. In comparison with the existing retrieval algorithms, the CRGM potentially reduces related computational uncertainties and errors from BLH determination (strong increase of correlation coefficient from 0.44 to 0.91 and significant decrease of the root mean square error from 643 m to 142 m). Such newly developed technique is undoubtedly expected to contribute to improve the accuracy of air quality modelling and forecasting systems.

scholarly journals Relationships between the planetary boundary layer height and surface pollutants derived from lidar observations over China

2018 ◽  
Author(s):  
Tianning Su ◽  
Zhanqing Li ◽  
Ralph Kahn
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Negative Correlation ◽  
North China Plain ◽  
North China ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
The North ◽  
The North China Plain

Abstract. The frequent occurrence of severe air pollution episodes in China has raised great concerns with the public and scientific communities. Planetary boundary layer height (PBLH) is a key factor in the vertical mixing and dilution of near-surface pollutants. However, the relationship between PBLH and surface pollutants, especially particulate matter (PM) concentration, across the whole of China, is not yet well understood. We investigate this issue at ~ 1500 surface stations using PBLH derived from space-borne and ground-based lidar, and discuss the influence of topography and meteorological variables on the PBLH-PM relationship. A generally negative correlation is observed between PM and the PBLH, albeit varying greatly in magnitude with location and season. Correlations are much weaker over the highlands than plains regions, which may be associated with lower pollution levels and mountain breezes. The influence of horizontal transport on surface PM is considered as well, manifested as a negative correlation between surface PM and wind speed over the whole nation. Strong wind with clean upwind sources plays a dominant role in removing pollutants, and leads to weak PBLH-PM correlation. A ventilation rate is introduced to jointly consider horizontal and vertical dispersion, which has the largest impact on surface pollutant accumulation over the North China Plain. Aerosol absorption feedbacks also appear to affect the PBLH-PM relationship, as revealed via comparing air pollution in Beijing and Hong Kong. Absorbing aerosols in high concentrations likely contribute to the significant PBLH-PM correlation over the North China Plain (e.g., during winter). As major precursor emissions for secondary aerosols, sulfur dioxide, nitrogen dioxide, and carbon monoxide have similar negative responses to increased PBLH, whereas ozone is positively correlated with PBLH over most regions, which may be caused by heterogeneous reactions and photolysis rates.

scholarly journals Ceilometer Monitoring of Boundary-Layer Height and Its Application in Evaluating the Dilution Effect on Air Pollution

2019 ◽  
Vol 172 (3) ◽  
pp. 435-455 ◽  
Author(s):  
Junhong Lee ◽  
Je-Woo Hong ◽  
Keunmin Lee ◽  
Jinkyu Hong ◽  
Erik Velasco ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Dilution Effect ◽  
Layer Height ◽  
Boundary Layer Height

scholarly journals Set of Algorithms and Techniques for Accurate 3D, Single Beam – Single Pointing, Lidar Measurements for Slant Range Visibility, Planetary Boundary Layer Height and Wind Speed Retrieval, Atmospheric Layers Spatial Distribution and Categorization in Real Time

2020 ◽  
Vol 237 ◽  
pp. 02031
Author(s):  
Alexandros Pantazis ◽  
Alexandros Papayannis
Keyword(s):  
Boundary Layer ◽  
Spatial Distribution ◽  
Wind Speed ◽  
Real Time ◽  
Planetary Boundary Layer ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Single Beam ◽  
Slant Range ◽  
Boundary Layer Height

In this work, a full set of recently developed algorithms and techniques is presented, for a single beam-single pointing lidar to be able to perform operational and independent accurate 3 Dimensional (3D) measurements, for slant range visibility, wind speed retrieval, atmospheric layers spatial distribution and categorization, as well as Planetary Boundary Layer Height (PBLH) retrieval, in real or Near Real Time (NRT).The idea behind this development was for any single lidar to be able to perform a set of accurately measured products, either mobile or stationary, with or without network connectivity with other sensors for data-information exchange. The products were determined by the needs of lidar remote scientific and commercial community, in order to be even more attractive and valuable to atmospheric scientists, meteorologists, aviation and shipping safety operators, as well as to the Space lidar community.

scholarly journals Hurricane Boundary Layer Height Relative to Storm Motion from GPS Dropsonde Composites

Atmosphere ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 339 ◽  
Author(s):  
Yifang Ren ◽  
Jun A. Zhang ◽  
Stephen R. Guimond ◽  
Xiang Wang
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Layer Depth ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Tangential Wind ◽  
Hurricane Boundary Layer ◽  
The Right

This study investigates the asymmetric distribution of hurricane boundary layer height scales in a storm-motion-relative framework using global positioning system (GPS) dropsonde observations. Data from a total of 1916 dropsondes collected within four times the radius of maximum wind speed of 37 named hurricanes over the Atlantic basin from 1998 to 2015 are analyzed in the composite framework. Motion-relative quadrant mean composite analyses show that both the kinematic and thermodynamic boundary layer height scales tend to increase with increasing radius in all four motion-relative quadrants. It is also found that the thermodynamic mixed layer depth and height of maximum tangential wind speed are within the inflow layer in all motion-relative quadrants. The inflow layer depth and height of the maximum tangential wind are both found to be deeper in the two front quadrants, and they are largest in the right-front quadrant. The difference in the thermodynamic mixed layer depth between the front and back quadrants is smaller than that in the kinematic boundary layer height. The thermodynamic mixed layer is shallowest in the right-rear quadrant, which may be due to the cold wake phenomena. The boundary layer height derived using the critical Richardson number ( R i c ) method shows a similar front-back asymmetry as the kinematic boundary layer height.

scholarly journals Relationships between the planetary boundary layer height and surface pollutants derived from lidar observations over China: regional pattern and influencing factors

2018 ◽  
Vol 18 (21) ◽  
pp. 15921-15935 ◽  
Author(s):  
Tianning Su ◽  
Zhanqing Li ◽  
Ralph Kahn
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Planetary Boundary Layer ◽  
North China Plain ◽  
North China ◽  
Strong Wind ◽  
Planetary Boundary Layer Height ◽  
Near Surface ◽  
Layer Height ◽  
Boundary Layer Height

Abstract. The frequent occurrence of severe air pollution episodes in China has been a great concern and thus the focus of intensive studies. Planetary boundary layer height (PBLH) is a key factor in the vertical mixing and dilution of near-surface pollutants. However, the relationship between PBLH and surface pollutants, especially particulate matter (PM) concentration across China, is not yet well understood. We investigate this issue at ∼1600 surface stations using PBLH derived from space-borne and ground-based lidar, and discuss the influence of topography and meteorological variables on the PBLH–PM relationship. Albeit the PBLH–PM correlations are roughly negative for most cases, their magnitude, significance, and even sign vary considerably with location, season, and meteorological conditions. Weak or even uncorrelated PBLH–PM relationships are found over clean regions (e.g., Pearl River Delta), whereas nonlinearly negative responses of PM to PBLH evolution are found over polluted regions (e.g., North China Plain). Relatively strong PBLH–PM interactions are found when the PBLH is shallow and PM concentration is high, which typically corresponds to wintertime cases. Correlations are much weaker over the highlands than the plains regions, which may be associated with lighter pollution loading at higher elevations and contributions from mountain breezes. The influence of horizontal transport on surface PM is considered as well, manifested as a negative correlation between surface PM and wind speed over the whole nation. Strong wind with clean upwind air plays a dominant role in removing pollutants, and leads to obscure PBLH–PM relationships. A ventilation rate is used to jointly consider horizontal and vertical dispersion, which has the largest impact on surface pollutant accumulation over the North China Plain. As such, this study contributes to improved understanding of aerosol–planetary boundary layer (PBL) interactions and thus our ability to forecast surface air pollution.

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