scholarly journals Ventilation coefficient and boundary layer height impact on urban air quality

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
P. Sujatha ◽  
D.V. Mahalakshmi ◽  
A. Ramiz ◽  
P.V.N. Rao ◽  
C.V. Naidu
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Urban Air Quality ◽  
Urban Air ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Ventilation Coefficient

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.

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

2021 ◽  
Vol 21 (12) ◽  
pp. 9573-9583
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 whose lifetime is 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.

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.

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

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;

Seasonal and episodic influence of local meteorology on fine particulate matter at a regional background site in North East India.

2021 ◽  
Author(s):  
Adnan Qadri ◽  
Shahadev Rabha ◽  
Binoy Saikia ◽  
Tarun Gupta
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Ambient Air ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Wind Speeds ◽  
Background Site ◽  
North East ◽  
Regional Background ◽  
Ventilation Coefficient

&lt;p&gt;Climatological parameters like wind speed, temperature, boundary layer height facilitate in dispersion and accumulation of aerosols. Stagnant condition of atmosphere promote accumulation while the pollutants are more likely to get dispersed when non stagnation conditions exist. Sparse studies exist to assess the seasonal and episodic impact of stagnant weather conditions on enhancing aerosol formation in the North-East region of India.PM&lt;sub&gt;2.5 &lt;/sub&gt;sampling was carried from January to November 2019 at a regional background site in Jorhat,Assam. Meteorological variables like wind speed, surface ambient temperature and relative humidity were obtained at one-minute resolution from a collocated air weather sensor. Ventilation coefficient was calculated from wind speed and Boundary Layer Height (BLH) ( from ERA5 reanalysis dataset)&lt;/p&gt;&lt;p&gt;Episodic days were identified as those exceeding permissible values of PM&lt;sub&gt;2.5 &lt;/sub&gt;(National Ambient Air Quality Standards) i.e, 60&amp;#181;g/m&lt;sup&gt;3&lt;/sup&gt;. Average wind speed on polluted and non-polluted days was 0.58&amp;#177;0.08 and 0.77 &amp;#177; 0.17 m/s respectively. The average BLH was lower for the polluted days (243&amp;#177;73) than the non-polluted days (316&amp;#177;79). Pearson corelation coefficient of PM&lt;sub&gt;2.5 &lt;/sub&gt;and wind speeds on polluted days was low (-0.23) compared to the non-polluted days (-0.54).&lt;/p&gt;&lt;p&gt;Wind rose plots reveal a seasonality trend with winter and summer winds being mostly between North East and South South-West while in monsoon and autumn it lies predominantly between SSW and South South-East (from the Bay of Bengal). &amp;#160;The Pearson correlation coefficients between PM&lt;sub&gt;2.5 &lt;/sub&gt;and wind speeds are -0.66, -0.54 and -0.52 (all p &lt;0.01) in winter, summer and autumn, respectively.Low average BLH persists in Winter and autumn . The seasonal maxima of BLH during winter, summer, monsoon and autumn was 847&amp;#177;167m, 932 &amp;#177; 271m, 871 &amp;#177;275m and 814 &amp;#177; 256m, respectively.&amp;#160; Low night-time BLH (&amp;#8776; 50m) in winter and autumn contributes to higher aerosol loading.&amp;#160;The ventilation coefficient reaches its maxima during daytime around noon with summer season having the maximum daytime VC. High VC (&amp;#8776;270m&lt;sup&gt;2&lt;/sup&gt;/s) in summer and monsoon&amp;#160; signify the seasonal effect on the pollutant dispersion and consequent high PM&lt;sub&gt;2.5 &lt;/sub&gt;loading. Statistically significant negative correlations were obtained between PM&lt;sub&gt;2.5 &lt;/sub&gt;and VC in winter and autumn seasons (-0.75 and -0.43).&lt;/p&gt;&lt;p&gt;Wind speeds have a strong correlation with PM&lt;sub&gt;2.5 &lt;/sub&gt;except for the monsoon season and play a major role in aerosol dispersion.During monsoon, weak dependence of PM&lt;sub&gt;2.5 &lt;/sub&gt;with wind speed and ventilation coefficient suggest significance of precipitation&amp;#160; which cause sscavenging of aerosols. Low correlations exist in summer for PM&lt;sub&gt;2.5 &lt;/sub&gt;and VC due to possible interference due to regional transport of aerosols. 5-day backward trajectory analysis suggest&amp;#160; transport of air masses across the Thar desert and Indo Gangetic Plains to the site during the March(summer) suggesting transport of dust across the region.&lt;/p&gt;

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 Correlation Study of Planetary-Boundary-Layer-Height Retrievals from CL51 and CHM15K Ceilometers with Application To PM2.5 Dynamics in New York City

2020 ◽  
Vol 237 ◽  
pp. 03010
Author(s):  
Dingdong Li ◽  
Barry Gross ◽  
Yonghua Wu ◽  
Fred Moshary
Keyword(s):  
Boundary Layer ◽  
New York ◽  
New York City ◽  
Air Quality ◽  
Planetary Boundary Layer ◽  
York City ◽  
Critical Role ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height

Planetary-boundary-layer-height (PBLH) plays a critical role in the study of urban air quality, weather and climate. Continuous observation is critical in understanding air pollution processes and evaluation of air quality/ weather models in the complex urban environment. In this study, we observe the PBLH variation using multiple ceilometers and lidar in New York City (NYC) during both the summer and winter time and explore the potential correlation with ground PM2.5. An automated quality control and quality assurance (QC/QA) method is developed to optimize the PBLH determination from the ceilometers (Vaisala CL51 and Lufft CHM15k) product. The PBLHs from the two ceilometers and lidar show good consistency (R2=0.68~0.88) during the convective PBL period at 15:00-21:00 UTC (10:00-16:00 EST). We also investigate the seasonal variation and diurnal evolution of PBLH and demonstrate an inverse relation between the PBLH and PM2.5 during the morning transient period of PBLH growth. Further, the correlation between the ceilometer-attenuated backscatter and ground PM2.5 and its dependences on the vertical altitude are analyzed, showing that the aerosols in the PBL are more deeply mixed while also being influenced by the relatively high humidity variability during the summer.

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