Design of the Mexico City UV monitoring network: UV-B measurements at ground level in the urban environment

2000 ◽  
Vol 105 (D4) ◽  
pp. 5017-5026 ◽  
Author(s):  
L. R. Acosta ◽  
W. F. J. Evans
Keyword(s):  
Urban Environment ◽  
Mexico City ◽  
Monitoring Network ◽  
Ground Level

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>

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.

scholarly journals The Functional Spatio-Temporal Statistical Model with Application to O3 Pollution in Beijing, China

2020 ◽  
Vol 17 (9) ◽  
pp. 3172
Author(s):  
Yaqiong Wang ◽  
Ke Xu ◽  
Shaomin Li
Keyword(s):  
Statistical Model ◽  
Diurnal Cycle ◽  
Monitoring Network ◽  
Temporal Correlation ◽  
Ground Level ◽  
Quality Data ◽  
Ozone Pollution ◽  
Spatial Correlation Structure ◽  
Spatio Temporal ◽  
Beijing China

In recent years, with rapid industrialization and massive energy consumption, ground-level ozone ( O 3 ) has become one of the most severe air pollutants. In this paper, we propose a functional spatio-temporal statistical model to analyze air quality data. Firstly, since the pollutant data from the monitoring network usually have a strong spatial and temporal correlation, the spatio-temporal statistical model is a reasonable method to reveal spatial correlation structure and temporal dynamic mechanism in data. Secondly, effects from the covariates are introduced to explore the formation mechanism of ozone pollution. Thirdly, considering the obvious diurnal pattern of ozone data, we explore the diurnal cycle of O 3 pollution using the functional data analysis approach. The spatio-temporal model shows great applicational potential by comparison with other models. With application to O 3 pollution data of 36 stations in Beijing, China, we give explanations of the covariate effects on ozone pollution, such as other pollutants and meteorological variables, and meanwhile we discuss the diurnal cycle of ozone pollution.

scholarly journals Comparison of tropospheric NO<sub>2</sub> vertical columns in an urban environment using satellite, multi-axis differential optical absorption spectroscopy, and in situ measurements

2013 ◽  
Vol 6 (10) ◽  
pp. 2907-2924 ◽  
Author(s):  
D. Mendolia ◽  
R. J. C. D'Souza ◽  
G. J. Evans ◽  
J. Brook
Keyword(s):  
Optical Absorption ◽  
Urban Environment ◽  
Absorption Spectroscopy ◽  
Ground Level ◽  
Remotely Sensed ◽  
Differential Optical Absorption Spectroscopy ◽  
Optical Absorption Spectroscopy ◽  
Vertical Column ◽  
Above Ground Level

Abstract. Tropospheric NO2 vertical column densities have been retrieved and compared for the first time in Toronto, Canada, using three methods of differing spatial scales. Remotely sensed NO2 vertical column densities, retrieved from multi-axis differential optical absorption spectroscopy and satellite remote sensing, were evaluated by comparison with in situ vertical column densities estimated using a pair of chemiluminescence monitors situated 0.01 and 0.5 km a.g.l. (above ground level). The chemiluminescence measurements were corrected for the influence of NOz, which reduced the NO2 concentrations at 0.01 and 0.5 km by an average of 8 ± 1% and 12 ± 1%, respectively. The average absolute decrease in the chemiluminescence NO2 measurement as a result of this correction was less than 1 ppb. The monthly averaged ratio of the NO2 concentration at 0.5 to 0.01 km varied seasonally, and exhibited a negative linear dependence on the monthly average temperature, with Pearson's R = 0.83. During the coldest month, February, this ratio was 0.52 ± 0.04, while during the warmest month, July, this ratio was 0.34 ± 0.04, illustrating that NO2 is not well mixed within 0.5 km above ground level. Good correlation was observed between the remotely sensed and in situ NO2 vertical column densities (Pearson's R value ranging from 0.72 to 0.81), but the in situ vertical column densities were 52 to 58% greater than the remotely sensed columns. These results indicate that NO2 horizontal heterogeneity strongly impacted the magnitude of the remotely sensed columns. The in situ columns reflected an urban environment with major traffic sources, while the remotely sensed NO2 vertical column densities were representative of the region, which included spatial heterogeneity introduced by residential neighbourhoods and Lake Ontario. Despite the difference in absolute values, the reasonable correlation between the vertical column densities determined by three distinct methods increased confidence in the validity of the values provided by each measurement technique.

scholarly journals Poles together

1993 ◽  
Vol 5 (4) ◽  
pp. 333-333
Author(s):  
W. F. Vincent
Keyword(s):  
Monitoring Network ◽  
Ground Level ◽  
Ultraviolet B ◽  
Atmospheric Environment ◽  
Research Areas ◽  
Vital Interest ◽  
Research Findings ◽  
Biological Impacts ◽  
Antarctic Ozone ◽  
The Antarctic

In March 1993 the Atmospheric Environment Service's monitoring network across Canada registered ground-level fluxes of solar ultraviolet-B radiation (UVBR) that were the highest on record. This effect was correlated with the spring-time depletion of ozone in the northern upper atmosphere, and AES predicted that the average depletion over Canada could be this severe or worse for the next 15–20 years. These reports heightened awareness amongst the Canadian public as well as the scientific community about the Antarctic ozone hole, and about the most recent UVBR and atmospheric research findings from Antarctica. The causes and biological impacts of high latitude ozone depletion is but one example where information derived from one polar zone is of vital interest to those living in, or otherwise concerned with the other. In this and other research areas the time is appropriate for a bipolar perspective on Antarctica.

‘Public’ Security and Patron–Client Exchanges in Latin America

2013 ◽  
Vol 48 (4) ◽  
pp. 548-569 ◽  
Author(s):  
Markus-Michael Müller
Keyword(s):  
Latin America ◽  
Local Government ◽  
Urban Environment ◽  
Mexico City ◽  
Public Security ◽  
The Political ◽  
Authoritarian Rule ◽  
Local Police ◽  
Local Politicians ◽  
Changing Patterns

Notwithstanding the democratization processes that have taken place since the 1980s, clientelism continues to be an important political practice throughout contemporary Latin America. By offering an analysis of the changing patterns of patron–client exchanges in Mexico City, this article demonstrates how the repercussions of the local democratization process expanded clientelist practices to the realm of public security provision. This expansion, it is argued, is related to efforts of the local government to regain previous levels of political control over the local police forces that had been undermined by the fragmentation of long-standing national patron–client structures under authoritarian rule. Additionally, it is demonstrated that in an increasingly insecure urban environment, local politicians and brokers realized the political gains to be derived from expanding clientelist exchanges to the realm of security provision.

Mexico City: The Production and Reproduction of an Urban Environment

1991 ◽  
Vol 157 (2) ◽  
pp. 211
Author(s):  
Ann Varley ◽  
Peter M. Ward
Keyword(s):  
Urban Environment ◽  
Mexico City

scholarly journals Compositional situation: analysis of the location of two sculptures in Mexico City

1970 ◽  
Vol 14 (3) ◽  
pp. 42-49
Author(s):  
Leszek Maluga
Keyword(s):  
Urban Environment ◽  
Mexico City ◽  
Research Method ◽  
Public Spaces ◽  
Situation Analysis ◽  
The Public ◽  
Works Of Art ◽  
Spatial Systems ◽  
The Subject

The study consists of two parts. In the first one, the author outlines a methodological concept of researching the quality of compositional and artistic spatial systems that are created, for example, in the urban environment with the participation of, inter alia, architectural objects and works of art. The subject of this type of research was called a ‘compositional situation’. In the second part, the author uses the proposed research method to analyze specific cases. These are two situations existing in the public spaces of Mexico City, in which sculptures of famous Mexican sculptor Sebastian were located.

scholarly journals Formaldehyde total column densities over Mexico City: comparison between MAX-DOAS and solar absorption FTIR measurements

2020 ◽  
Author(s):  
Claudia Rivera Cárdenas ◽  
Cesar Guarín ◽  
Wolfgang Stremme ◽  
Martina M. Friedrich ◽  
Alejandro Bezanilla ◽  
...  
Keyword(s):  
Mexico City ◽  
Measurement Techniques ◽  
Mixing Layer ◽  
Ground Level ◽  
Urban Site ◽  
Optical Absorption Spectroscopy ◽  
Vertical Column ◽  
Solar Absorption ◽  
Diurnal Variability ◽  
Total Column

Abstract. Formaldehyde (HCHO) total column densities over the Mexico City Metropolitan Area (MCMA) were retrieved using two independent measurement techniques: Multi Axis – Differential Optical Absorption Spectroscopy (MAX-DOAS) and Fourier Transform Infrared (FTIR) Spectroscopy. For the MAX-DOAS measurements, the software QDOAS was used to calculate differential Slant Column Densities (dSCDs) from the measured spectra and subsequently the Mexican MAX-DOAS Fit retrieval code (MMF) to convert from dSCDs to Vertical Column Densities (VCDs). The direct-solar absorption spectra measured with FTIR were analyzed using the PROFFIT retrieval code. Typically the MAX-DOAS instrument reports higher VCDs than those measured with FTIR, in part due to differences found in the ground-level sensitivities as revealed from the retrieval diagnostics from both instruments. Three MAX-DOAS datasets using measurements conducted towards the east, west or both sides of the measurement plane were evaluated with respect to the FTIR results. The retrieved MAX-DOAS HCHO VCDs where 5 %, 9 % and 28 % larger than the FTIR which, supported with satellite data, could demonstrate a large horizontal inhomogeneity in the HCHO abundances. A time-dependent comparison revealed that the vertical distribution of this pollutant, guided by the evolution of the mixing layer height, can play an important role in how the results are affected. Apart from the reported seasonal and diurnal variability of HCHO columns within the urban site, background data from measurements at a high-altitude station, located only 60 km away are presented.

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