scholarly journals Vertical distribution of aerosols in Mexico City during MILAGRO-2006 campaign

2009 ◽  
Vol 9 (2) ◽  
pp. 6827-6854
Author(s):  
P. A. Lewandowski ◽  
W. E. Eichinger ◽  
H. Holder ◽  
J. Prueger
Keyword(s):  
Vertical Distribution ◽  
Mexico City ◽  
Extinction Coefficient ◽  
Mass Extinction ◽  
Heavy Traffic ◽  
Monitoring Network ◽  
Aerosol Size Distribution ◽  
Lidar System ◽  
Aerosol Loading ◽  
Mass Extinction Efficiency

Abstract. On 7 March 2006, a mobile, ground-based, vertical pointing, elastic lidar system made a North-South transect through the Mexico City basin. Aerosol size distribution measurements, made concurrently, allowed calculation of the mass extinction efficiency (MEE) for the lidar system (1064 nm). MEE combined with an inverted lidar extinction coefficient resulted in total aerosol vertical mass estimates with 1.5 m vertical spatial and 1 s temporal resolution. The results showed that the aerosol loading within the basin is about twice what is observed outside of the basin. The total aerosol base concentrations observed in the basin are of the order of 200 μg/m3 and the base levels outside are of the order of 100 μg/m3. The local heavy traffic events can introduce aerosol levels near the ground as high as 900 μg/m3. The lidar-based total aerosol loading compares with the hourly-averaged PM10 ground observations conducted by the RAMA monitoring network throughout Mexico City.

scholarly journals Vertical distribution of aerosols in the vicinity of Mexico City during MILAGRO-2006 Campaign

2010 ◽  
Vol 10 (3) ◽  
pp. 1017-1030 ◽  
Author(s):  
P. A. Lewandowski ◽  
W. E. Eichinger ◽  
H. Holder ◽  
J. Prueger ◽  
J. Wang ◽  
...  
Keyword(s):  
Size Distribution ◽  
Mexico City ◽  
Mass Concentration ◽  
Heavy Traffic ◽  
Aerosol Size Distribution ◽  
Lidar System ◽  
Aerosol Mass ◽  
Aerosol Mass Concentration ◽  
Lidar Measurements ◽  
Ground Based Lidar

Abstract. On 7 March 2006, a mobile, ground-based, vertical pointing, elastic lidar system made a North-South transect through the Mexico City basin. Column averaged, aerosol size distribution (ASD) measurements were made on the ground concurrently with the lidar measurements. The ASD ground measurements allowed calculation of the column averaged mass extinction efficiency (MEE) for the lidar system (1064 nm). The value of column averaged MEE was combined with spatially resolved lidar extinction coefficients to produce total aerosol mass concentration estimates with the resolution of the lidar (1.5 m vertical spatial and 1 s temporal). Airborne ASD measurements from DOE G-1 aircraft made later in the day on 7 March 2006, allowed the evaluation of the assumptions of constant ASD with height and time used for estimating the column averaged MEE. The results showed that the aerosol loading within the basin is about twice what is observed outside of the basin. The total aerosol base concentrations observed in the basin are of the order of 200 μg/m3 and the base levels outside are of the order of 100 μg/m3. The local heavy traffic events can introduce aerosol levels near the ground as high as 900 μg/m3. The article presents the methodology for estimating aerosol mass concentration from mobile, ground-based lidar measurements in combination with aerosol size distribution measurements. An uncertainty analysis of the methodology is also presented.

scholarly journals Mass Extinction Efficiency Approximation for Polydispersed Aerosol Using Harmonic Mean-Type Approximation

2020 ◽  
Vol 10 (23) ◽  
pp. 8637
Author(s):  
Junshik Um ◽  
Seonghyeon Jang ◽  
Young Jun Yoon ◽  
Seoung Soo Lee ◽  
Ji Yi Lee ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Extinction Coefficient ◽  
Mass Extinction ◽  
Aerosol Particles ◽  
Size Distributions ◽  
Extinction Efficiency ◽  
Type Approximation ◽  
Aerosol Mass ◽  
Mass Extinction Efficiency

Among many parameters characterizing atmospheric aerosols, aerosol mass extinction efficiency (MEE) is important for understanding the optical properties of aerosols. MEE is expressed as a function of the refractive indices (i.e., composition) and size distributions of aerosol particles. Aerosol MEE is often considered as a size-independent constant that depends only on the chemical composition of aerosol particles. The famous Malm’s reconstruction equation and subsequent revised methods express the extinction coefficient as a function of aerosol mass concentration and MEE. However, the used constant MEE does not take into account the effect of the size distribution of polydispersed chemical composition. Thus, a simplified expression of size-dependent MEE is required for accurate and conventional calculations of the aerosol extinction coefficient and also other optical properties. In this study, a simple parameterization of MEE of polydispersed aerosol particles was developed. The geometric volume–mean diameters of up to 10 µm with lognormal size distributions and varying geometric standard deviations were used to represent the sizes of various aerosol particles (i.e., ammonium sulfate and nitrate, elemental carbon, and sea salt). Integrating representations of separate small mode and large mode particles using a harmonic mean-type approximation generated the flexible and convenient parameterizations of MEE that can be readily used to process in situ observations and adopted in large-scale numerical models. The calculated MEE and the simple forcing efficiency using the method developed in this study showed high correlations with those calculated using the Mie theory without losing accuracy.

Determination of aerosol extinction coefficient and mass extinction efficiency by DOAS with a flashlight source

2005 ◽  
Vol 14 (11) ◽  
pp. 2360-2364 ◽  
Author(s):  
Si Fu-Qi ◽  
Liu Jian-Guo ◽  
Xie Ping-Hua ◽  
Zhang Yu-Jun ◽  
Liu Wen-Qing ◽  
...  
Keyword(s):  
Extinction Coefficient ◽  
Mass Extinction ◽  
Aerosol Extinction ◽  
Extinction Efficiency ◽  
Aerosol Extinction Coefficient ◽  
Mass Extinction Efficiency

scholarly journals Evidence for the predictability of changes in the stratospheric aerosol size following volcanic eruptions of diverse magnitudes using space-based instruments

2020 ◽  
Author(s):  
Larry W. Thomason ◽  
Mahesh Kovilakam ◽  
Anja Schmidt ◽  
Christian von Savigny ◽  
Travis Knepp ◽  
...  
Keyword(s):  
Size Distribution ◽  
Extinction Coefficient ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Global Climate Models ◽  
Aerosol Size Distribution ◽  
Aerosol Layer ◽  
Aerosol Extinction ◽  
Volcanic Event ◽  
Aerosol Extinction Coefficient

Abstract. An analysis of multiwavelength stratospheric aerosol extinction coefficient data from the Stratospheric Aerosol and Gas Experiment II and III/ISS instruments is used to demonstrate a coherent relationship between the perturbation in extinction coefficient in an eruption's main aerosol layer and an apparent change in aerosol size distribution that spans multiple orders of magnitude in the stratospheric impact of a volcanic event. The relationship is measurement-based and does not rely on assumptions about the aerosol size distribution. We note limitations on this analysis including that the presence of significant amounts of ash in the main aerosol layer may significantly modulate these results. Despite this limitation, these findings represent a unique opportunity to verify the performance of interactive aerosol models used in Global Climate Models and Earth System Model and may suggest an avenue for improving aerosol extinction coefficient measurements from single channel observations such the Optical Spectrograph and Infrared Imager System as they rely on a priori assumptions about particle size.

scholarly journals Evidence for the predictability of changes in the stratospheric aerosol size following volcanic eruptions of diverse magnitudes using space-based instruments

2021 ◽  
Vol 21 (2) ◽  
pp. 1143-1158 ◽  
Author(s):  
Larry W. Thomason ◽  
Mahesh Kovilakam ◽  
Anja Schmidt ◽  
Christian von Savigny ◽  
Travis Knepp ◽  
...  
Keyword(s):  
Extinction Coefficient ◽  
Climate Models ◽  
Single Channel ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Global Climate Models ◽  
Aerosol Size Distribution ◽  
Aerosol Layer ◽  
Aerosol Extinction ◽  
Aerosol Extinction Coefficient

Abstract. An analysis of multiwavelength stratospheric aerosol extinction coefficient data from the Stratospheric Aerosol and Gas Experiment II and III/ISS instruments is used to demonstrate a coherent relationship between the perturbation in extinction coefficient in an eruption's main aerosol layer and the wavelength dependence of that perturbation. This relationship spans multiple orders of magnitude in the aerosol extinction coefficient of stratospheric impact of volcanic events. The relationship is measurement-based and does not rely on assumptions about the aerosol size distribution. We note limitations on this analysis including that the presence of significant amounts of ash in the main sulfuric acid aerosol layer and other factors may significantly modulate these results. Despite these limitations, the findings suggest an avenue for improving aerosol extinction coefficient measurements from single-channel observations such as the Optical Spectrograph and Infrared Imager System as they rely on a prior assumptions about particle size. They may also represent a distinct avenue for the comparison of observations with interactive aerosol models used in global climate models and Earth system models.

Impacts of COVID-19 lockdown strategies on NOx, CO and CO2 surface observations on two megacities: focus on the traffic sector in Mexico City (Mexico) and Paris (France)

2021 ◽  
Author(s):  
Sophie Tran ◽  
Michel Ramonet ◽  
Thomas Lauvaux ◽  
Philippe Ciais ◽  
Olivier Laurent ◽  
...  
Keyword(s):  
Mexico City ◽  
Road Traffic ◽  
Anthropogenic Activities ◽  
Atmospheric Dispersion ◽  
Monitoring Network ◽  
Economic Activities ◽  
Capital Cities ◽  
Pollutant Concentrations ◽  
Travel Restrictions ◽  
Co Concentrations

<p><span>In 2020, the COVID-19 pandemic imposed countries to apply stringent policies to slow down the spread of the SARS-CoV-2 virus. During the Spring time, most countries had announced a national lockdown that had important consequences on many capital cities such as Mexico City and Paris. The shutdown of many of these economic activities had a direct impact on the traffic sector. Travel restrictions led to a drastic decrease of major air pollutants in those two cities. From each local air quality monitoring network, we discriminated background, urban and traffic sites. By looking at the differences between urban sites versus background sites, we observed in Mexico City a decrease of 51%, 58 % and 44 % for </span><span>Δ</span><span>NO</span><sub><span>x</span></sub><span>, </span><span>Δ</span><span>CO</span><sub><span>2</span></sub><span> and </span><span>Δ</span><span>CO concentrations, respectively, during the lockdown. Markedly, their concentrations remained below typical levels after the end of the lockdown until September. Then, from September to the end of the year, the pollutants concentrations increased back to the same level as before the lockdown. The same behavior was seen at Paris. During the spring lockdown period, we observed a decrease of 72 %, 70 % and 88 % for </span><span>Δ</span><span>NO</span><sub><span>x</span></sub><span>, </span><span>Δ</span><span>CO</span><sub><span>2</span></sub><span> and </span><span>Δ</span><span>CO concentrations, respectively. Until the end of the summer, the concentrations of those pollutants remained at the same level as during the lockdown. From September, we observed an increase of pollutants concentrations to the levels of previous years. </span></p><p><span>Despite road traffic increases by the end of the lockdown in both megacities, the remainly low concentrations seen for those pollutants until September might be an effect of the atmospheric dispersion combined with a slow reactivation of anthropogenic activities. Nevertheless, a second lockdown period imposed in France (from Oct. 30 to Dec. 15) have clearly not shown the same impact on pollutant concentrations as the first one exhibited. On the contrary, no significant changes in pollutant concentrations were observed during the second lockdown, and moreover, peaks of </span><span>Δ</span><span>NO</span><sub><span>x</span></sub><span>, </span><span>Δ</span><span>CO</span><sub><span>2</span></sub><span> and </span><span>Δ</span><span>CO concentrations were seen during the last weekends of the lockdown of up to 32 % of increase, compared to the weekday-level during the 2nd lockdown. This can be explained by less stringent travel restrictions combined with pre-Christmas preparations in Paris. </span></p>

Vertical Distribution of Aerosol Extinction Coefficient Detection in Boundary Layer Using CCD Lidar

2013 ◽  
Vol 33 (8) ◽  
pp. 0801003
Author(s):  
孟祥谦 Meng Xiangqian ◽  
胡顺星 Hu Shunxing ◽  
王珍珠 Wang Zhenzhu ◽  
胡欢陵 Hu Huanling ◽  
王英俭 Wang Yingjian
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Extinction Coefficient ◽  
Aerosol Extinction ◽  
Aerosol Extinction Coefficient

Aggregation-driven reductions in the mass extinction coefficient of bioaerosols

Optik ◽  
2019 ◽  
Vol 184 ◽  
pp. 115-120 ◽  
Author(s):  
Xinying Zhao ◽  
Yihua Hu ◽  
Youlin Gu ◽  
Xi Chen ◽  
Xinyu Wang ◽  
...  
Keyword(s):  
Extinction Coefficient ◽  
Mass Extinction

Photochemical assessment monitoring stations program adapted for ozone precursors monitoring network in Mexico City

Atmósfera ◽  
2016 ◽  
Vol 29 (2) ◽  
pp. 169 ◽  
Author(s):  
Mónica Del Carmen Jaimes Palomera ◽  
Humberto Bravo Álvarez ◽  
Rodolfo Sosa Echeverria ◽  
Elías Granados Hernández ◽  
Pablo Sánchez Álvarez ◽  
...  
Keyword(s):  
Mexico City ◽  
Atmospheric Chemistry ◽  
Control Strategies ◽  
Monitoring Network ◽  
Ozone Precursors ◽  
The Us ◽  
Us Epa ◽  
Photochemical Modeling ◽  
Urban Ozone ◽  
Monitoring Stations

The purpose of this study is to select a number of stations from the existing Sistema de Monitoreo Atmosférico (Atmospheric Monitoring System, SIMAT) of Mexico City to serve as an equivalent to the Photochemical Assessment Monitoring Stations according to the US-EPA criteria, in order to improve the study of urban ozone occurrence. The results indicate that four existing SIMAT stations meet the criteria to form such network. The relevance of this study is to present an ozone precursors monitoring network with continuous measurements for future trustful studies on air quality for ozone, considering the atmospheric chemistry and photochemical modeling for the design control strategies appropriate for the particular conditions of Mexico City.

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