Interpretation of Atmospheric CO2 Measurements in Mexico City

2021 ◽  
Author(s):  
Yang Xu ◽  
Michel Ramonet ◽  
Thomas Lauvaux ◽  
Jinghui Lian ◽  
Francois-Marie Bréon ◽  
...  
Keyword(s):  
Mexico City ◽  
Rural Areas ◽  
Ghg Emissions ◽  
Single Layer ◽  
Urban Canopy ◽  
Horizontal Resolution ◽  
Complex Topography ◽  
Urban Station ◽  
Mountain Areas ◽  
Mixing Ratios

<p>The French-Mexican project Mexico City’s Regional Carbon Impacts (MERCI-CO<sub>2</sub>) is building a CO<sub>2</sub> observation network in the Metropolitan Zone of the Valley of Mexico (ZMVM). The project investigates the atmospheric signals generated by the city's emissions on total column and surface measurements, aiming at reducing the uncertainties of CO<sub>2</sub> emissions in ZMVM and evaluating the effects of policies that had been implemented by the city authorities. </p><p>A nested high-resolution atmospheric transport simulation based on the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) is performed to analyze the observed CO<sub>2</sub> mixing ratios during dry and wet seasons over Mexico City and its vicinity. Both anthropogenic emissions (UNAM 1-km fossil fuel emissions) and biogenic fluxes (CASA 5-km simulations) are taken into account. The model configuration, with a horizontal resolution of 1km and using the Single-Layer urban canopy Model (SLUCM), has been evaluated over two weeks in January 2018 using meteorological measurements from 26 stations set by the Air Quality Agency of Mexico City (Secretary of the Environment of Mexico City - SEDEMA). The reconstruction of meteorological conditions in the urban area shows better performances than suburban and mountainous areas. Due to the complex topography, wind speeds in mountain areas are 2-3 m/s over estimated and wind direction simulations in some stations are 90° deflected, especially in southern mountains. </p><p>Two high-precision CO<sub>2</sub> analyzers deployed in urban and rural areas of Mexico City are used to evaluate the WRF CO<sub>2</sub> 1-km simulations. The model reproduced the diurnal cycle of CO<sub>2</sub> mixing ratios at the background station but under-estimates the nighttime accumulation at the urban station. Mean absolute errors of CO<sub>2</sub> concentrations range from 6.5 ppm (background station) to 27.1 ppm (urban station), mostly driven by the elevated nocturnal enhancements (up to 500 ppm at UNAM station). Based on this analysis, we demonstrate the challenges and potential of mesoscale modeling over complex topography, and the potential use of mid-cost sensors to constrain the urban GHG emissions of Mexico City.</p>

scholarly journals CO<sub>2</sub> dispersion modelling over Paris region within the CO<sub>2</sub>-MEGAPARIS project

2013 ◽  
Vol 13 (9) ◽  
pp. 4941-4961 ◽  
Author(s):  
C. Lac ◽  
R. P. Donnelly ◽  
V. Masson ◽  
S. Pal ◽  
S. Riette ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Temporal Variability ◽  
Urban Areas ◽  
Onset Time ◽  
Urban Canopy ◽  
Horizontal Resolution ◽  
Spatial And Temporal Variability ◽  
Good Representation ◽  
Mixing Ratios ◽  
Urban Rural

Abstract. Accurate simulation of the spatial and temporal variability of tracer mixing ratios over urban areas is a challenging and interesting task needed to be performed in order to utilise CO2 measurements in an atmospheric inverse framework and to better estimate regional CO2 fluxes. This study investigates the ability of a high-resolution model to simulate meteorological and CO2 fields around Paris agglomeration during the March field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric model Meso-NH, running at 2 km horizontal resolution, is coupled with the Town Energy Balance (TEB) urban canopy scheme and with the Interactions between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs) surface scheme, allowing a full interaction of CO2 modelling between the surface and the atmosphere. Statistical scores show a good representation of the urban heat island (UHI) with stronger urban–rural contrasts on temperature at night than during the day by up to 7 °C. Boundary layer heights (BLH) have been evaluated on urban, suburban and rural sites during the campaign, and also on a suburban site over 1 yr. The diurnal cycles of the BLH are well captured, especially the onset time of the BLH increase and its growth rate in the morning, which are essential for tall tower CO2 observatories. The main discrepancy is a small negative bias over urban and suburban sites during nighttime (respectively 45 m and 5 m), leading to a few overestimations of nocturnal CO2 mixing ratios at suburban sites and a bias of +5 ppm. The diurnal CO2 cycle is generally well captured for all the sites. At the Eiffel tower, the observed spikes of CO2 maxima occur every morning exactly at the time at which the atmospheric boundary layer (ABL) growth reaches the measurement height. At suburban ground stations, CO2 measurements exhibit maxima at the beginning and at the end of each night, when the ABL is fully contracted, with a strong spatio-temporal variability. A sensitivity test without urban parameterisation removes the UHI and underpredicts nighttime BLH over urban and suburban sites, leading to large overestimation of nocturnal CO2 mixing ratio at the suburban sites (bias of +17 ppm). The agreement between observation and prediction for BLH and CO2 concentrations and urban–rural increments, both day and night, demonstrates the potential of using the urban mesoscale system in the context of inverse modelling

scholarly journals Technoeconomic Analysis and Environmental Impact of Electric Vehicle Introduction in Taxis: A Case Study of Mexico City

2021 ◽  
Vol 12 (3) ◽  
pp. 93
Author(s):  
Daniel Arturo Maciel Fuentes ◽  
Eduardo Gutiérrez González
Keyword(s):  
Environmental Impact ◽  
Mexico City ◽  
Life Cycle Cost ◽  
Renewable Energy Sources ◽  
Ghg Emissions ◽  
Pollutant Emissions ◽  
Transport Sector ◽  
Maintenance Cost ◽  
Slight Reduction ◽  
Technoeconomic Analysis

In recent decades, urban air pollution has increased considerably in Mexico City, leading to harmful effects on the ecosystem. To reduce pollutant emissions, new sustainable technologies have been adopted in the transport sector. To date, no studies have conducted a technoeconomic analysis of the environmental impact of electric vehicles (EVs) in regard to taxis in Mexico. To address this gap in the research, this study aimed to perform a cost-environmental impact assessment of electric taxi introduction in Mexico City using the life-cycle cost (LCC) methodology and the greenhouse gas (GHG) emissions assessment. Furthermore, a sensitivity analysis was performed to identify parameters with the greatest influence on the LCC. The LCC of EVs was found to be larger than that of internal combustion vehicles (ICVs); the acquisition cost was identified as the greatest contributor to the total LCC, followed by the maintenance cost. Worldwide, mixed results have been reported due to differences in the use of local parameters and values. To promote EVs, it is necessary to reduce either acquisition costs or battery costs. The environmental analysis showed that there is only a slight reduction in GHG emissions with electric taxi introduction. Nevertheless, cleaner renewable energy sources must be adopted and considered in order to achieve a much greater reduction and take full advantage of the benefits of EVs.

scholarly journals Assessing the regional impacts of Mexico City emissions on air quality and chemistry

2009 ◽  
Vol 9 (11) ◽  
pp. 3731-3743 ◽  
Author(s):  
M. Mena-Carrasco ◽  
G. R. Carmichael ◽  
J. E. Campbell ◽  
D. Zimmerman ◽  
Y. Tang ◽  
...  
Keyword(s):  
Air Quality ◽  
Mexico City ◽  
Ozone Production ◽  
Anthropogenic Aerosol ◽  
Near Surface ◽  
Mixing Ratios ◽  
Regional Impacts ◽  
Photolysis Rates ◽  
Regional Air Quality ◽  
The Impact

Abstract. The impact of Mexico City (MCMA) emissions is examined by studying its effects on air quality, photochemistry, and on ozone production regimes by combining model products and aircraft observations from the MILAGRO experiment during March 2006. The modeled influence of MCMA emissions to enhancements in surface level NOx, CO, and O3 concentrations (10–30% increase) are confined to distances <200 km, near surface. However, the extent of the influence is significantly larger at higher altitudes. Broader MCMA impacts (some 900 km Northeast of the city) are shown for specific outflow conditions in which enhanced ozone, NOy, and MTBE mixing ratios over the Gulf of Mexico are linked to MCMA by source tagged tracers and sensitivity runs. This study shows that the "footprint" of MCMA on average is fairly local, with exception to reactive nitrogen, which can be transported long range in the form of PAN, acting as a reservoir and source of NOx with important regional ozone formation implications. The simulated effect of MCMA emissions of anthropogenic aerosol on photochemistry showed a maximum regional decrease of 40% in J[NO2→NO+O], and resulting in the reduction of ozone production by 5–10%. Observed ozone production efficiencies are evaluated as a function of distance from MCMA, and by modeled influence from MCMA. These tend to be much lower closer to MCMA, or in those points where modeled contribution from MCMA is large. This research shows that MCMA emissions do effect on regional air quality and photochemistry, both contributing large amounts of ozone and its precursors, but with caveat that aerosol concentrations hinder formation of ozone to its potential due to its reduction in photolysis rates.

An Impedance Sensor of Water Cut with Three Electrodes and Relative Analysis on Experiment Results

2021 ◽  
Author(s):  
Chuan Yu ◽  
Qinghai Yang ◽  
Songbo Wei ◽  
Ming Li ◽  
Tao Fu
Keyword(s):  
Single Layer ◽  
High Water ◽  
Sensor Calibration ◽  
Mixing Ratios ◽  
Margin Of Error ◽  
Measurement Results ◽  
Oil Water ◽  
High Water Cut ◽  
Water Cut ◽  
Impedance Sensor

Abstract Single-layer water cut measurement is of great significance for identifying and shutting off the unwanted water, analyzing oil remained and optimizing production. Currently, however, only the water cut of multilayer mixture can be measured by testing samples taken from wellhead, a way which is widely used in oilfields. That of single-layer fluid cannot be determined yet To address the problem, this paper puts forward a new impedance sensor that offers long-term online monitoring of single-layer water cut. This sensor is based on the different electrical conductivity of oil and water. It has two layers. The inner one contains three electrodes - two at both sides sending sinusoidal excitation signals and one at the middle receiving signals that have been attenuated by the water-oil medium. With the Maxwell's model of oil-water mixed fluid, the receiver then can measure the water cut online. The outer layer of the sensor is made of PEEK, an insulative protection. In front of the electrodes lies a static mixer which makes the measurement more accurate by fully blending the two media when they flow through the electrodes. Laboratory tests are carried out with the prototype of the sensor at various oil-water mixing ratios, fluid flow rates, and temperatures. Results show that the average margin of error is within ± 3%. Higher accuracy is seen when high water cut and flow rate enable oil globules to disperse more evenly and the space in between to get wider and the RMS error is less than 2%. If the water cut drops below 80%, the aggregation of the droplets will cause wild fluctuation and more errors in the measurement. In addition, the mineralization of the mixture directly changes its conductivity, which largely impacts the result. Meanwhile, temperature can influence the ionic movement intensity and then alter the conductivity of the medium. Therefore, in practice, the sensor calibration needs to be performed according to the range of medium salinity, and the temperature of the medium is collected in real time for temperature compensation. It is shown that after the adjustment, the water cut measurement results have higher accuracy and consistency. The impedance sensor can realize online water cut monitoring for a single-layer, indicated by tests. It is more suitable for the increasing high water cut oilfields in that it is more accurate as the water cut grows.

scholarly journals Relative Role of Turbulent and Radiative Flux on the Near-Surface Temperature in a Single-Layer Urban Canopy Model over Houston

2017 ◽  
Vol 56 (8) ◽  
pp. 2173-2187 ◽  
Author(s):  
James Brownlee ◽  
Pallav Ray ◽  
Mukul Tewari ◽  
Haochen Tan
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Single Layer ◽  
Urban Canopy ◽  
Heat Fluxes ◽  
Radiative Flux ◽  
Hydrological Processes ◽  
Urban Canopy Model ◽  
Near Surface ◽  
Canopy Model

AbstractNumerical simulations without hydrological processes tend to overestimate the near-surface temperatures over urban areas. This is presumably due to underestimation of surface latent heat flux. To test this hypothesis, the existing single-layer urban canopy model (SLUCM) within the Weather Research and Forecasting Model is evaluated over Houston, Texas. Three simulations were conducted during 24–26 August 2000. The simulations include the use of the default “BULK” urban scheme, the SLUCM without hydrological processes, and the SLUCM with hydrological processes. The results show that the BULK scheme was least accurate, and it overestimated the near-surface temperatures and winds over the urban regions. In the presence of urban hydrological processes, the SLUCM underestimates these parameters. An analysis of the surface heat fluxes suggests that the error in the BULK scheme is due to a lack of moisture at the urban surface, whereas the error in the SLUCM with hydrological processes is due to increases in moisture at the urban surface. These results confirm earlier studies in which changes in near-surface temperature were primarily due to the changes in the turbulent (latent and sensible heat) fluxes in the presence of hydrological processes. The contribution from radiative flux was about one-third of that from turbulent flux. In the absence of hydrological processes, however, the results indicate that the changes in radiative flux contribute more to the near-surface temperature changes than the turbulent heat flux. The implications of these results are discussed.

scholarly journals Level 2 processing for the imaging Fourier transform spectrometer GLORIA: derivation and validation of temperature and trace gas volume mixing ratios from calibrated dynamics mode spectra

2015 ◽  
Vol 8 (6) ◽  
pp. 2473-2489 ◽  
Author(s):  
J. Ungermann ◽  
J. Blank ◽  
M. Dick ◽  
A. Ebersoldt ◽  
F. Friedl-Vallon ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Horizontal Resolution ◽  
Trace Gas ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Ionization Mass ◽  
Fourier Transform Spectrometer ◽  
Upper Troposphere ◽  
Mixing Ratios

Abstract. The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an airborne infrared limb imager combining a two-dimensional infrared detector with a Fourier transform spectrometer. It was operated aboard the new German Gulfstream G550 High Altitude LOng Range (HALO) research aircraft during the Transport And Composition in the upper Troposphere/lowermost Stratosphere (TACTS) and Earth System Model Validation (ESMVAL) campaigns in summer 2012. This paper describes the retrieval of temperature and trace gas (H2O, O3, HNO3) volume mixing ratios from GLORIA dynamics mode spectra that are spectrally sampled every 0.625 cm−1. A total of 26 integrated spectral windows are employed in a joint fit to retrieve seven targets using consecutively a fast and an accurate tabulated radiative transfer model. Typical diagnostic quantities are provided including effects of uncertainties in the calibration and horizontal resolution along the line of sight. Simultaneous in situ observations by the Basic Halo Measurement and Sensor System (BAHAMAS), the Fast In-situ Stratospheric Hygrometer (FISH), an ozone detector named Fairo, and the Atmospheric chemical Ionization Mass Spectrometer (AIMS) allow a validation of retrieved values for three flights in the upper troposphere/lowermost stratosphere region spanning polar and sub-tropical latitudes. A high correlation is achieved between the remote sensing and the in situ trace gas data, and discrepancies can to a large extent be attributed to differences in the probed air masses caused by different sampling characteristics of the instruments. This 1-D processing of GLORIA dynamics mode spectra provides the basis for future tomographic inversions from circular and linear flight paths to better understand selected dynamical processes of the upper troposphere and lowermost stratosphere.

scholarly journals The seasonal variability of the amount of global solar radiation reaching the ground in urban and rural areas on the example of Warsaw and Belsk

2016 ◽  
Vol 20 (4) ◽  
pp. 29-37
Author(s):  
Kinga Nelken ◽  
Kamil Leziak
Keyword(s):  
Solar Radiation ◽  
Urban Area ◽  
Rural Area ◽  
Rural Areas ◽  
Meteorological Data ◽  
Global Solar Radiation ◽  
Urban Station ◽  
Reverse Relationship ◽  
Urban And Rural Areas ◽  
The Relationship

AbstractThe aim of this paper is to determine the contemporary differences in the inflow of global solar radiation in Warsaw (urban station) and Belsk (rural station). The meteorological data used comprised daily sums of global solar radiation (in MJ•m−2) and the duration of sunshine (in hours) for the period 2008 2014. On clear days in spring and summer, the rural area receives more solar radiation in comparison to the urban area, whereas in autumn a reverse relationship occurs. On cloudy days in all seasons, the rural area receives more solar radiation than the urban area, and the relationship is the strongest in winter. Differences between urban and rural areas on cloudy days are smaller than those observed on clear days.

scholarly journals The Use of Draught Animals in Rural Labour

Animals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2683
Author(s):  
Daniel Mota-Rojas ◽  
Ada Braghieri ◽  
Adolfo Álvarez-Macías ◽  
Francesco Serrapica ◽  
Efrén Ramírez-Bribiesca ◽  
...  
Keyword(s):  
Rural Areas ◽  
Close Contact ◽  
Low Cost ◽  
Ghg Emissions ◽  
Renewable Energy Consumption ◽  
High Prevalence ◽  
Economic Constraints ◽  
By Products ◽  
Draught Animals

This study discusses scientific findings on the use of draught animals such as equids (i.e., horses, mules, and donkeys) and bovids (i.e., cattle and water buffaloes) in rural labours. Relevant peer-reviewed literature published between 1980 and 2021 was retrieved from CAB Abstracts, PubMed, ISI Web of Knowledge, and Scopus databases. Although animals were used to produce draught power since their domestication and are still being used for this purpose, mechanisation has markedly reduced animal labour demand in agriculture. However, the process was uneven across continents according to economic constraints, and draught animals are currently concentrated in small production units located on terrains that do not favour agriculture mechanisation in Africa, Latin America, and Asia. Generally, equids can work at rates similar to those of bovids or faster but can sustain the work for shorter periods of time. In addition, buffaloes possess tough hooves and resistance to disease that make them suitable for working in wetlands and clay soils. Draught animals allow a marked reduction of both GHG emissions and non-renewable energy consumption as compared with agricultural machinery. In addition, they may allow obtaining profits from otherwise non-usable lands. Therefore, their use should be promoted in rural areas where low investments are usually the only ones feasible, and the energy of the animals can be obtained at a low cost by feeding them harvest residues and by-products. However, more attention should be paid to the quality of human–animal interactions—due to the close contact between animals and humans while working—and to the welfare of draught animals when transported and slaughtered—due to the high prevalence of injuries they suffer when subjected to these practices.

scholarly journals Summertime impacts of Eastern Mediterranean megacity emissions on air quality

2011 ◽  
Vol 11 (9) ◽  
pp. 26657-26690 ◽  
Author(s):  
U. Im ◽  
M. Kanakidou
Keyword(s):  
Air Quality ◽  
Rural Areas ◽  
Eastern Mediterranean ◽  
Anthropogenic Emissions ◽  
Urban Agglomerations ◽  
Mixing Ratios ◽  
Urban Core ◽  
Local Contribution ◽  
Regional Air Quality ◽  
Inorganic Aerosol

Abstract. Megacities are large urban agglomerations with intensive anthropogenic emissions that have significant impacts on local and regional air quality. In the present mesoscale modeling study, the impacts of anthropogenic emissions from Istanbul and Athens on local and regional air quality in the Eastern Mediterranean are quantified and the responses to hypothetical decentralization scenarios applied to the extended areas of these densely populated regions are evaluated. This study focuses on summertime impacts on air quality. The results show that Athens emissions have larger regional (0.8%) and downwind (2.7% at Finokalia) impacts on O3 than Istanbul emissions that contribute to surface O3 by 0.6% to the domain-mean and 2.1% to the levels at Finokalia. On the opposite, regarding fine particle (PM2.5) levels, Istanbul emissions have larger contribution both inside the megacity itself (75%) and regionally (2.4%) compared to Athens emissions, which have a local contribution of 65% and domain-wide contribution of 0.4%. Biogenic emissions are found to limit the production of secondary inorganic aerosol species due to their impact on oxidant levels. Hypothetical decentralization plans for these urban agglomerations, maintaining the total amount of their anthropogenic emissions constant but homogeneously distributing it over larger "new" extended areas, would result in higher O3 mixing ratios inside the urban core (215% and 26% in Istanbul and Athens, respectively). On the opposite, PM2.5 concentrations would decrease by 67% and 60% in Istanbul and Athens, respectively, whereas they would increase by 10% and 11% in the rural areas of Istanbul and Athens, respectively. Concerning the "new" extended areas, Athens would experience a reduction in O3 mixing ratios by ~2% whereas Istanbul would experience an increase by ~15%. Overall decreases of PM2.5 levels by 32% and 9% are calculated over the Istanbul and Athens "new" extended areas.

scholarly journals Rural development limitations at the transitional terms

2003 ◽  
Vol 44 (159) ◽  
pp. 159-171 ◽  
Author(s):  
Marija Nikolic ◽  
Marija Maksin-Micic
Keyword(s):  
Rural Development ◽  
Rural Areas ◽  
Leisure Activities ◽  
National Level ◽  
Social Changes ◽  
Rural Settlements ◽  
Mountain Areas ◽  
Integrated Rural Development ◽  
European Experience ◽  
Green Tourism

European countries have been reaffirtmating the role and the significance of agricultural multifunctionality for rural areas development. The transition countries have to make the assessment of their weaknesses and opportunities before facing the necessary significant investments in agriculture, rural settlements and deprived rural areas. Overall economic development should provide for further agriculture employment reduction, along with taking measures for the agriculture farms modernization and changes in the structure of agriculture production, within the process of integrated rural development. Declining population at mountain areas might be a prerequisite for intensified farm restructuring, namely through development reorientation, achieving more balanced agriculture economy, along with rediscovering comparative advantages in the development of new activities linked to social changes and changes in lifestyle - green tourism, leisure activities, health care, as well as to forestry, traditional crafts etc. Subsequent to European experience in maintenance of the necessary level of spatial development in sparsely populated and neglected rural areas, the development of priority mountain areas in Serbia should be defined at national level, and the new system of support should facilitate the preparation and the implementation of different projects for integrated rural development of this priority areas.

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