scholarly journals Pollutant Concentration Changes During the COVID-19 Lockdown in Barcelona and Surrounding Regions: Modification of Diurnal Cycles and Limited Role of Meteorological Conditions

2021 ◽  
Author(s):  
Miguel García-Dalmau ◽  
Mireia Udina ◽  
Joan Bech ◽  
Yolanda Sola ◽  
Joan Montolio ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Wind Speed ◽  
Road Traffic ◽  
Regional Scale ◽  
Meteorological Conditions ◽  
Surrounding Area ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Concentration Changes

AbstractOne of the consequences of the COVID-19 lockdowns has been the modification of the air quality in many cities around the world. This study focuses on the variations in pollutant concentrations and how important meteorological conditions were for those variations in Barcelona and the surrounding area during the 2020 lockdown. Boundary-layer height, wind speed, and precipitation were compared between mid-March and April 2016–2019 (pre-lockdown) and the same period in 2020 (during lockdown). The results show the limited influence of meteorological factors on horizontal and vertical dispersion conditions. Compared with the pre-lockdown period, during lockdown the boundary-layer height slightly increased by between 5% and 9%, mean wind speed was very similar, and the fraction of days with rainfall increased only marginally, from 0.33 to 0.34, even though April 2020 was extremely wet in the study area. Variations in nitrogen dioxide ($$\hbox {NO}_{{2}}$$ NO 2 ), particulate matter with a diameter less than 10 $${\mu }$$ μ m (PM10), and ozone ($$\hbox {O}_{{3}}$$ O 3 ) concentrations over a 10-year period showed a 66% reduction in $$\hbox {NO}_{{2}}$$ NO 2 , 37% reduction in PM10, and 27% increase in $$\hbox {O}_{{3}}$$ O 3 at a traffic station in Barcelona. The differences in the daily concentration cycle between weekends and weekdays were heavily smoothed for all pollutants considered. The afternoon $$\hbox {NO}_{{2}}$$ NO 2 peak at the traffic station was suppressed compared with the average daily cycle. The analysis of ozone was extended to the regional scale, revealing lower concentrations at rural sites and higher ones in urban zones, especially in Barcelona and the surrounding area. The results presented not only complement previous air quality COVID-19 lockdown studies but also provide insights into the effects of road-traffic reduction.

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 A Review of Techniques for Diagnosing the Atmospheric Boundary Layer Height (ABLH) Using Aerosol Lidar Data

2019 ◽  
Vol 11 (13) ◽  
pp. 1590 ◽  
Author(s):  
Ruijun Dang ◽  
Yi Yang ◽  
Xiao-Ming Hu ◽  
Zhiting Wang ◽  
Shuwen Zhang
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Atmospheric Boundary Layer ◽  
Weather Prediction ◽  
Mixing Layer ◽  
Accurate Estimation ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Vertical Distributions ◽  
Multi Wavelength

The height of the atmospheric boundary layer (ABLH) or the mixing layer height (MLH) is a key parameter characterizing the planetary boundary layer, and the accurate estimation of that is critically important for boundary layer related studies, which include air quality forecasts and numerical weather prediction. Aerosol lidar is a powerful remote sensing instrument frequently used to retrieve the ABLH through detecting the vertical distributions of aerosol concentration. Presently available methods for ABLH determination from aerosol lidar are summarized in this review, including a lot of classical methodologies as well as some improved versions of them. Some new recently developed methods applying advanced techniques such as image edge detection, as well as some new methods based on multi-wavelength lidar systems, are also summarized. Although a lot of techniques have been proposed and have already given reasonable results in several studies, it is impossible to recommend a technique which is suitable in all atmospheric scenarios. More accurate instantaneous ABLH from robust techniques is required, which can be used to estimate or improve the boundary layer parameterization in the numerical model, or maybe possible to be assimilated into the weather and environment models to improve the simulation or forecast of weather and air quality in the future.

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.

Factors influencing the boundary layer height and their relationship with air quality in the Sichuan Basin, China

2020 ◽  
Vol 727 ◽  
pp. 138584 ◽  
Author(s):  
Bangjun Cao ◽  
Xiaoyan Wang ◽  
Guicai Ning ◽  
Liang Yuan ◽  
Mengjiao Jiang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Sichuan Basin ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Factors Influencing ◽  
The Sichuan Basin

scholarly journals The “urban meteorology island”: a multi-model ensemble analysis

2020 ◽  
Vol 20 (23) ◽  
pp. 15061-15077
Author(s):  
Jan Karlický ◽  
Peter Huszár ◽  
Tereza Nováková ◽  
Michal Belda ◽  
Filip Švábik ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Regional Climate Model ◽  
Cloud Cover ◽  
Climate Model ◽  
Regional Climate ◽  
Meteorological Variables ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Induced Changes

Abstract. Cities and urban areas are well-known for their impact on meteorological variables and thereby modification of the local climate. Our study aims to generalize the urban-induced changes in specific meteorological variables by introducing a single phenomenon – the urban meteorology island (UMI). A wide ensemble of 24 model simulations with the Weather Research and Forecasting (WRF) regional climate model and the Regional Climate Model (RegCM) on a European domain with 9 km horizontal resolution were performed to investigate various urban-induced modifications as individual components of the UMI. The results show that such an approach is meaningful, because in nearly all meteorological variables considered, statistically significant changes occur in cities. Besides previously documented urban-induced changes in temperature, wind speed and boundary-layer height, the study is also focused on changes in cloud cover, precipitation and humidity. An increase in cloud cover in cities, together with a higher amount of sub-grid-scale precipitation, is detected on summer afternoons. Specific humidity is significantly lower in cities. Further, the study shows that different models and parameterizations can have a strong impact on discussed components of the UMI. Multi-layer urban schemes with anthropogenic heat considered increase winter temperatures by more than 2 ∘C and reduce wind speed more strongly than other urban models. The selection of the planetary-boundary-layer scheme also influences the urban wind speed reduction, as well as the boundary-layer height, to the greatest extent. Finally, urban changes in cloud cover and precipitation are mostly sensitive to the parameterization of convection.

scholarly journals The potential for geostationary remote sensing of NO<sub>2</sub> to improve weather prediction

2020 ◽  
Author(s):  
Xueling Liu ◽  
Arthur P. Mizzi ◽  
Jeffrey L. Anderson ◽  
Inez Fung ◽  
Ronald C. Cohen
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Air Quality ◽  
Data Assimilation ◽  
Weather Prediction ◽  
Urban Air ◽  
Atmospheric Conditions ◽  
Wind Fields ◽  
Layer Height ◽  
Boundary Layer Height

Abstract. Observations of winds in the planetary boundary layer remain sparse making it challenging to simulate and predict atmospheric conditions that are most important for describing and predicting urban air quality. Short-lived chemicals are observed as plumes whose location is affected by boundary layer winds and with a lifetime affected by boundary layer height and mixing. Here we investigate the application of data assimilation of NO2 columns as will be observed from geostationary orbit to improve predictions and retrospective analysis of wind fields in the boundary layer.

Factors influencing the boundary layer height and their relationship with air quality in the Sichuan Basin, China

2020 ◽  
Author(s):  
Bangjun Cao
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Sichuan Basin ◽  
Wind Shear ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Factors Influencing ◽  
The Sichuan Basin

&lt;p&gt;We investigated the factors influencing the daily maximum boundary layer height (h&lt;sub&gt;max&lt;/sub&gt;) and their relationship with air quality in the Sichuan Basin, China. We analyzed the factors influencing h&lt;sub&gt;max&lt;/sub&gt; on cloudy and sunny days in winter using five years of observational data and a reanalysis dataset and investigated the relationship between h&lt;sub&gt;max&lt;/sub&gt; and air quality. The inversion layer in the lower troposphere has a critical impact on h&lt;sub&gt;max&lt;/sub&gt; on cloudy days. By contrast, the sensible heat flux and wind shear are the main influencing factors on sunny days, although the contribution of the sensible heat flux to h&lt;sub&gt;max&lt;/sub&gt; is less than that of the wind shear. This is because the turbulence is mainly affected by mechanical mixing induced by the topographic effect of the Tibetan Plateau to the west of the Sichuan Basin. The secondary circulation over the Sichuan Basin is weaker on cloudy days than on sunny days. These results are important for understanding the dispersion of air pollutants over the Sichuan Basin.&lt;/p&gt;

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