scholarly journals Atmospheric Changes and Ozone Increase in Mexico City during 2020 Lockdown Period

2021 ◽  
Author(s):  
Sakthi Selvalakshmi Jeyakumar ◽  
Jonathan Muthuswamy Ponniah ◽  
Gopalakrishnan Gnanachandrasamy ◽  
Sandra Soledad Morales-Garcia ◽  
Pedro Francisco Rodríguez-Espinosa ◽  
...  
Keyword(s):  
Mexico City ◽  
Photochemical Reaction ◽  
Meteorological Parameters ◽  
Meteorological Factors ◽  
Anthropogenic Activities ◽  
Who Guidelines ◽  
Atmospheric Pollutant ◽  
The North ◽  
Household Activities ◽  
Atmospheric Changes

Abstract Atmospheric pollutant (NO2, SO2, CO, O3 and PM2.5) variations during the COVID-19 pandemic (during 2020) have been studied from Mexico City in Central America. Meteorological factors (i.e) rainfall, temperature along with relative humidity played an important role in increasing the photochemical reaction for the formation of O3 and PM2.5. Concentration pattern of O3 and PM2.5 were higher in all the stations in spite of the reduced primary pollutants. However, higher level of O3 and PM2.5 during the lockdown period in 2020 is mainly due to the air-mass exchange which happened through the broader channel in the north (Tenango del Aire Pass) and in the southeast (Cuautla-Cuernavaca valley). The higher values of particulate matter are compensated by domestic heating (“Quédate en Casa”/ Stay at Home), whereas the increase of O3 is supported by the higher solar radiation and household activities (both indoor/ outdoor). Monitoring stations (BJ, GAM, UAM, SFE) in Mexico City indicate that the level of pollutants (except GAM) were within the WHO guidelines. Comparison of pollutants with other countries indicate a spike in NO2, O3 and PM2.5 levels. Overall results indicate that the anthropogenic activities which is influenced by the meteorological parameters has affected the air quality in Mexico City and it persisted during the lockdown period.

scholarly journals Striking forest revival at the end of the Roman Period in north-western Europe

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
C. Lambert ◽  
A. Penaud ◽  
M. Vidal ◽  
C. Gandini ◽  
L. Labeyrie ◽  
...  
Keyword(s):  
North Atlantic ◽  
Western Europe ◽  
Anthropogenic Activities ◽  
Sedimentary Environment ◽  
Pollen Grains ◽  
Roman Period ◽  
Freshwater Microalgae ◽  
Environmental Signals ◽  
The North ◽  
North Western

AbstractThe Holocene period (last 11,700 years BP) has been marked by significant climate variability over decadal to millennial timescales. The underlying mechanisms are still being debated, despite ocean–atmosphere–land connections put forward in many paleo-studies. Among the main drivers, involving a cluster of spectral signatures and shaping the climate of north-western Europe, are solar activity, the North Atlantic Oscillation (NAO) varying atmospheric regimes and North Atlantic oceanic gyre dynamics. Over the last 2500 years BP, paleo-environmental signals have been strongly affected by anthropogenic activities through deforestation and land use for crops, grazing, habitations, or access to resources. Palynological proxies (especially pollen grains and marine or freshwater microalgae) help to highlight such anthropogenic imprints over natural variability. Palynological analyses conducted in a macro-estuarine sedimentary environment of north-western France over the last 2500 years BP reveal a huge and atypical 300 year-long arboreal increase between 1700 and 1400 years BP (around 250 and 550 years AD) that we refer to as the ‘1.7–1.4 ka Arboreal Pollen rise event’ or ‘1.7–1.4 ka AP event’. Interestingly, the climatic 1700–1200 years BP interval coincides with evidence for the withdrawal of coastal societies in Brittany (NW France), in an unfavourable socio-economic context. We suggest that subpolar North Atlantic gyre strengthening and related increasing recurrence of storminess extremes may have affected long-term coastal anthropogenic trajectories resulting in a local collapse of coastal agrarian societies, partly forced by climatic degradation at the end of the Roman Period.

scholarly journals Modelling local patterns of child mortality risk: a Bayesian Spatio-temporal analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Alejandro Lome-Hurtado ◽  
Jacques Lartigue-Mendoza ◽  
Juan C. Trujillo
Keyword(s):  
High Risk ◽  
Mexico City ◽  
Child Mortality ◽  
Mortality Risk ◽  
Temporal Analysis ◽  
Health Concern ◽  
The North ◽  
Greater Mexico ◽  
Spatio Temporal ◽  
Child Mortality Rate

Abstract Background Globally, child mortality rate has remained high over the years, but the figure can be reduced through proper implementation of spatially-targeted public health policies. Due to its alarming rate in comparison to North American standards, child mortality is particularly a health concern in Mexico. Despite this fact, there remains a dearth of studies that address its spatio-temporal identification in the country. The aims of this study are i) to model the evolution of child mortality risk at the municipality level in Greater Mexico City, (ii) to identify municipalities with high, medium, and low risk over time, and (iii) using municipality trends, to ascertain potential high-risk municipalities. Methods In order to control for the space-time patterns of data, the study performs a Bayesian spatio-temporal analysis. This methodology permits the modelling of the geographical variation of child mortality risk across municipalities, within the studied time span. Results The analysis shows that most of the high-risk municipalities were in the east, along with a few in the north and west areas of Greater Mexico City. In some of them, it is possible to distinguish an increasing trend in child mortality risk. The outcomes highlight municipalities currently presenting a medium risk but liable to become high risk, given their trend, after the studied period. Finally, the likelihood of child mortality risk illustrates an overall decreasing tendency throughout the 7-year studied period. Conclusions The identification of high-risk municipalities and risk trends may provide a useful input for policymakers seeking to reduce the incidence of child mortality. The results provide evidence that supports the use of geographical targeting in policy interventions.

scholarly journals Relative timing of precipitation and ocean circulation changes in the western equatorial Atlantic over the last 45 kyr

2018 ◽  
Vol 14 (9) ◽  
pp. 1315-1330 ◽  
Author(s):  
Claire Waelbroeck ◽  
Sylvain Pichat ◽  
Evelyn Böhm ◽  
Bryan C. Lougheed ◽  
Davide Faranda ◽  
...  
Keyword(s):  
Mass Transport ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Wavelet Transforms ◽  
Water Mass ◽  
Sediment Cores ◽  
Equatorial Atlantic ◽  
The North ◽  
Atmospheric Changes ◽  
Circulation Changes

Abstract. Thanks to its optimal location on the northern Brazilian margin, core MD09-3257 records both ocean circulation and atmospheric changes. The latter occur locally in the form of increased rainfall on the adjacent continent during the cold intervals recorded in Greenland ice and northern North Atlantic sediment cores (i.e., Greenland stadials). These rainfall events are recorded in MD09-3257 as peaks in ln(Ti ∕ Ca). New sedimentary Pa ∕ Th data indicate that mid-depth western equatorial water mass transport decreased during all of the Greenland stadials of the last 40 kyr. Using cross-wavelet transforms and spectrogram analysis, we assess the relative phase between the MD09-3257 sedimentary Pa ∕ Th and ln(Ti ∕ Ca) signals. We show that decreased water mass transport between a depth of ∼1300 and 2300 m in the western equatorial Atlantic preceded increased rainfall over the adjacent continent by 120 to 400 yr at Dansgaard–Oeschger (D–O) frequencies, and by 280 to 980 yr at Heinrich-like frequencies. We suggest that the large lead of ocean circulation changes with respect to changes in tropical South American precipitation at Heinrich-like frequencies is related to the effect of a positive feedback involving iceberg discharges in the North Atlantic. In contrast, the absence of widespread ice rafted detrital layers in North Atlantic cores during D–O stadials supports the hypothesis that a feedback such as this was not triggered in the case of D–O stadials, with circulation slowdowns and subsequent changes remaining more limited during D–O stadials than Heinrich stadials.

scholarly journals Effects of lightning and other meteorological factors on fire activity in the North American boreal forest: implications for fire weather forecasting

2010 ◽  
Vol 10 (14) ◽  
pp. 6873-6888 ◽  
Author(s):  
D. Peterson ◽  
J. Wang ◽  
C. Ichoku ◽  
L. A. Remer
Keyword(s):  
Boreal Forest ◽  
North American ◽  
Meteorological Factors ◽  
Convective Available Potential Energy ◽  
Fire Weather ◽  
Lightning Strikes ◽  
The North ◽  
Lightning Detection ◽  
Western Boreal Forest ◽  
Consecutive Dry Days

Abstract. The effects of lightning and other meteorological factors on wildfire activity in the North American boreal forest are statistically analyzed during the fire seasons of 2000–2006 through an integration of the following data sets: the MODerate Resolution Imaging Spectroradiometer (MODIS) level 2 fire products, the 3-hourly 32-km gridded meteorological data from North American Regional Reanalysis (NARR), and the lightning data collected by the Canadian Lightning Detection Network (CLDN) and the Alaska Lightning Detection Network (ALDN). Positive anomalies of the 500 hPa geopotential height field, convective available potential energy (CAPE), number of cloud-to-ground lightning strikes, and the number of consecutive dry days are found to be statistically important to the seasonal variation of MODIS fire counts in a large portion of Canada and the entirety of Alaska. Analysis of fire occurrence patterns in the eastern and western boreal forest regions shows that dry (in the absence of precipitation) lightning strikes account for only 20% of the total lightning strikes, but are associated with (and likely cause) 40% of the MODIS observed fire counts in these regions. The chance for ignition increases when a threshold of at least 10 dry strikes per NARR grid box and at least 10 consecutive dry days is reached. Due to the orientation of the large-scale pattern, complex differences in fire and lightning occurrence and variability were also found between the eastern and western sub-regions. Locations with a high percentage of dry strikes commonly experience an increased number of fire counts, but the mean number of fire counts per dry strike is more than 50% higher in western boreal forest sub-region, suggesting a geographic and possible topographic influence. While wet lightning events are found to occur with a large range of CAPE values, a high probability for dry lightning occurs only when 500 hPa geopotential heights are above ~5700 m and CAPE values are near the maximum observed level, underscoring the importance of low-level instability to boreal fire weather forecasts.

scholarly journals The relationship between some meteorological parameters and the tropospheric concentrations of ozone in the urban area of Belgrade

2005 ◽  
Vol 70 (12) ◽  
pp. 1487-1495 ◽  
Author(s):  
Dragan Markovic ◽  
Dragan Markovic
Keyword(s):  
Meteorological Parameters ◽  
Wind Speeds ◽  
Ozone Concentrations ◽  
The North ◽  
Measuring Site ◽  
Ozone Transport ◽  
Photochemical Ozone ◽  
Low Wind Speeds ◽  
The Relationship ◽  
Tropospheric Concentrations

During the period between June and December 2002, the concentrations of ozone in the air at 4 measuring sites in Belgrade were measured. The measuring periods varied from 10 days to several weeks. The maximal measured daily concentrations of ozone ranged from 19ppbv (23 December 2002) to 118ppbv (23 June 2002).Ozone concentrations higher than, or equal to 90ppbv were registered at three measuring sites. It was shown that at measuring sites characterized as urban, maximal O3 concentrations equal to, or higher than 90ppbv occurred at high temperatures (higher than 30?C) and low wind speeds (mostly from the north). The measured ozone concentrations mostly showed characteristics usual for a daily photochemical ozone cycle, excluding the specificities influenced by the measuring site itself. Ozone transport was recorded at increased wind speeds, primarily from south-easterly directions. On the basis of he correlations between ozone concentration and the corresponding meteorological parameters, a validation of the measuring sites was performed from the aspect of their representativeness for the measurements.

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>

Enhanced atmospheric solubilization of iron due to anthropogenic activities

2021 ◽  
Author(s):  
Elisa Bergas-Massó ◽  
María Gonçalves Ageitos ◽  
Stelios Myriokefalitakis ◽  
Twan van Noije ◽  
Ron Miller ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Industrial Revolution ◽  
Anthropogenic Activities ◽  
Coupled Model ◽  
Anthropogenic Sources ◽  
Anthropogenic Activity ◽  
Sea Ice Concentration ◽  
Future Projections ◽  
The North ◽  
Primary Emissions

<p>Atmospheric deposition of soluble iron (Fe) to the ocean has an impact on oceanic primary productivity, thus on carbon dioxide uptake. Understanding how anthropogenic activity influences the atmospheric Fe cycle is key to project ocean biogeochemical cycles and has been barely explored.</p><p>In this study, we assess past, present, and future soluble Fe deposition to the ocean, accounting for natural and anthropogenic sources, using an advanced atmospheric Fe cycle module implemented into the EC-Earth3 Earth System Model. This version of the model considers primary emissions of insoluble and soluble Fe forms associated with dust minerals, and anthropogenic and biomass burning combustion aerosols. Fe solubilization processes in the atmosphere include 1)  proton-promoted, 2)  oxalate-promoted (with oxalate calculated on-line), and 3) photo-reductive Fe dissolution. We run time-slice simulations using the atmosphere-chemistry model configuration constrained by past, present, and future ocean states. The necessary sea surface temperature and sea ice concentration climatologies are obtained from EC-Earth3 CMIP6 coupled model experiments. Future projections rely on three CMIP6 scenarios representing different socio-economic pathways and end-of-the-century forcing levels: SSP1-2.6, SSP2-4.5, and SSP3-7.0. </p><p>Our setup allows us to estimate the soluble Fe deposition into the ocean while quantifying the contribution from dust, biomass burning, and anthropogenic combustion sources separately under a range of scenarios. Our preliminary results suggest nearly a 50% increase in soluble Fe deposition for the present time since the industrial revolution, attributed to increased atmospheric acidity and oxalate concentrations that result in a more efficient atmospheric processing. Future projections of soluble Fe show a high correlation between anthropogenic activity and solubility of deposited Fe, scenarios with higher anthropogenic emissions consistently yield a higher fraction of soluble over total deposited Fe. Our results also suggest diverging trends for the different ocean basins. Disentangling the factors that drive those differences in regions where Fe is known to be the limiting nutrient, such as the North Pacific or the Southern Ocean, is fundamental to improve our understanding of the atmospheric Fe cycle and its consequences for  the ocean biogeochemistry.  </p>

Fuentes the Young

PMLA ◽  
2013 ◽  
Vol 128 (3) ◽  
pp. 708-710
Author(s):  
John Ochoa
Keyword(s):  
Mexico City ◽  
North Sea ◽  
Public Service ◽  
Carlos Fuentes ◽  
Public Service Announcement ◽  
The Public ◽  
Late Night ◽  
The North ◽  
Pollution Problem ◽  
The North Sea

Carlos Fuentes was a dapper man. His physical bearing, his way of dressing, and his manners were all exquisite. He favored tailored Italian suits, supple loafers, pocket squares. He liked tony international places: he once said he owed the idea for La muerte de Artemio Cruz (1962; The Death of Artemio Cruz), perhaps the most “Mexican” of his novels, “to the North Sea and a beach in Holland” (Interview). But his cosmopolitanism got him into trouble, such as when a well-intentioned but off-key televised public-service announcement resulted in late-night TV parodies. Addressing the pollution problem in Mexico City, Fuentes pleaded for the public to save his “beloved” city—all while standing in an idyllic spot in Cambridge, England.

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