scholarly journals Spatial and temporal variations of air pollution over 41 cities of India during the COVID-19 lockdown period

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Krishna Prasad Vadrevu ◽  
Aditya Eaturu ◽  
Sumalika Biswas ◽  
Kristofer Lasko ◽  
Saroj Sahu ◽  
...  
Keyword(s):  
Air Pollution ◽  
Temporal Analysis ◽  
Temporal Variations ◽  
Northeast India ◽  
New Delhi ◽  
City Center ◽  
Coastal Cities ◽  
Vegetation Fires ◽  
Spatial Differences ◽  
The City

Abstract In this study, we characterize the impacts of COVID-19 on air pollution using NO2 and Aerosol Optical Depth (AOD) from TROPOMI and MODIS satellite datasets for 41 cities in India. Specifically, our results suggested a 13% NO2 reduction during the lockdown (March 25–May 3rd, 2020) compared to the pre-lockdown (January 1st–March 24th, 2020) period. Also, a 19% reduction in NO2 was observed during the 2020-lockdown as compared to the same period during 2019. The top cities where NO2 reduction occurred were New Delhi (61.74%), Delhi (60.37%), Bangalore (48.25%), Ahmedabad (46.20%), Nagpur (46.13%), Gandhinagar (45.64) and Mumbai (43.08%) with less reduction in coastal cities. The temporal analysis revealed a progressive decrease in NO2 for all seven cities during the 2020 lockdown period. Results also suggested spatial differences, i.e., as the distance from the city center increased, the NO2 levels decreased exponentially. In contrast, to the decreased NO2 observed for most of the cities, we observed an increase in NO2 for cities in Northeast India during the 2020 lockdown period and attribute it to vegetation fires. The NO2 temporal patterns matched the AOD signal; however, the correlations were poor. Overall, our results highlight COVID-19 impacts on NO2, and the results can inform pollution mitigation efforts across different cities of India.

Spatial and Temporal Differences in Weekday Travel Durations Between Private-for-Hire Transportation Services and Transit in the City Center

2021 ◽  
pp. 036119812110197
Author(s):  
Baxter Shandobil ◽  
Ty Lazarchik ◽  
Kelly Clifton
Keyword(s):  
Transportation Network ◽  
Central City ◽  
Temporal Analysis ◽  
Time Of Day ◽  
City Center ◽  
Transportation Services ◽  
Regulatory Frameworks ◽  
Transit Services ◽  
Level Information ◽  
The City

There is increasing evidence that ridehailing and other private-for-hire (PfH) services such as taxis and limousines are diverting trips from transit services. One question that arises is where and when PfH services are filling gaps in transit services and where they are competing with transit services that are publicly subsidized. Using weekday trip-level information for trips originating in or destined for the city center of Portland, OR from PfH transportation services (taxis, transportation network companies, limousines) and transit trip data collected from OpenTripPlanner, this study investigated the temporal and spatial differences in travel durations between actual PfH trips and comparable transit trips (the same origin–destination and time of day). This paper contributes to this question and to a growing body of research about the use of ridehailing and other on-demand services. Specifically, it provides a spatial and temporal analysis of the demand for PfH transportation using an actual census of trips for a given 2 week period. The comparison of trip durations of actual PfH trips to hypothetical transit trips for the same origin–destination pairs into or out of the central city gives insights for policy making around pricing and other regulatory frameworks that could be implemented in time and space.

scholarly journals Evolution of NO<sub><i>x</i></sub> in the Denver Urban Plume during the Front Range Air Pollution and Photochemistry Experiment

2017 ◽  
Author(s):  
Carlena J. Ebben ◽  
Tamara L. Sparks ◽  
Paul J. Wooldridge ◽  
Teresa L. Campos ◽  
Christopher A. Cantrell ◽  
...  
Keyword(s):  
Air Pollution ◽  
Numerical Models ◽  
Near Field ◽  
Photochemical Oxidation ◽  
Front Range ◽  
City Center ◽  
Alkyl Nitrates ◽  
Effective Lifetime ◽  
Urban Plume ◽  
The City

Abstract. As NOx (NOx ≡ NO + NO2) is transported away from cities, it undergoes photochemical oxidation to peroxynitrates (RO2NO2, ΣPNs), alkyl nitrates (RONO2, ΣANs), and nitric acid (HNO3). These higher oxide species each have different lifetimes to permanent removal or conversion back to NOx, resulting in nitrogen oxide chemistry that evolves as plumes are transported away from cities. Here, observations from the Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ) are used to describe the evolution of NOx and NOy (NOy ≡ NOx + ΣPNs + ΣANs + HNO3 + …) as the Denver urban plume flows outward from the city center. We evaluate the chemistry, dilution, and deposition rates in the plume to provide numerical constraints on the NOx and NOy,i lifetimes. We find that plume dilution with background air occurs with a lifetime of 3.5 hours. NOx concentrations decrease more rapidly with a lifetime to chemical loss and dilution of 2 hours in the near field of the city center. NOy has an effective lifetime of 3 hours and due to a combination of HNO3 deposition and dilution. The results provide a useful test of conceptual and numerical models of chemistry during the evolution of urban plumes.

scholarly journals Temporal analysis of air pollutants in the most affected monsoon region

2021 ◽  
Vol 23 (1) ◽  
pp. 229
Author(s):  
Omar Kairan ◽  
Nur Nasehah Zainudin ◽  
Nurul Hasya Mohd Hanafiah ◽  
Nur Emylia Arissa Mohd Jafri ◽  
Fukayhah Fatiha @Suhami ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Air Pollutants ◽  
Monsoon Season ◽  
Secondary Data ◽  
Ambient Air ◽  
Temporal Analysis ◽  
Quality Standard ◽  
Temporal Variations ◽  
Air Pollutant

Air pollution has become an issue at all rates in the world. In Malaysia, there is a system is known as air quality index (API) used to indicate the overall air quality in the country where the air pollutants include or the new ambient air quality standard are sulphur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3) and particulate matter with size less than 10 (PM10). The concentration levels of the air pollutants were said to be affected by the monsoon changes. Therefore, this study is conducted to examine the existence of temporal variations of each air pollutant then identify the differences of each air pollutants concentration in temporal variations. This study uses secondary data where data that has been retrieved from the Department of Environment (DOE) where it is data of air pollution specifically for Kota Bharu, kelantan records. Hierarchical agglomerative cluster analysis was conducted to group monthly air quality. As a conclusion, the study can conclude that the five air pollutants grouped into several different monthly clusters mostly representing the two main monsoon seasons. Mostly air pollutant varied accordingly towards the monsoon season. During the southwestern monsoon, air pollutant concentration tends to higher compare to the northeastern monsoon with mostly due to meteorological factors.

scholarly journals Integrated method for cities air temperature estimation

2016 ◽  
Author(s):  
Jérémy Bernard ◽  
Marjorie Musy ◽  
Isabelle Calmet ◽  
Erwan Bocher ◽  
Pascal Kéravec
Keyword(s):  
Air Temperature ◽  
Weather Conditions ◽  
Temporal Variations ◽  
Climatic Data ◽  
Integrated Method ◽  
Python Language ◽  
Spatial Differences ◽  
The Difference ◽  
Surrounding Areas ◽  
The City

Urban Heat Island (UHI) is defined as the air temperature difference between the city and its surrounding areas. This phenomenon varies spatially (depending on the type of urban fabric constituting each neighborhood) and temporally (depending on the time of the day, on the season and on the weather conditions). This contribution proposes a methodology to model the UHI spatially and temporally using simple models built with free and open sources softwares (orbisGIS and python language). Ten air temperature sensors have been implemented in several neighborhoods of the Nantes urban area (a west coast french conurbation). The difference of UHI is observed and modeled for each of those sites. Spatial differences are modeled according to geographical indicators characterizing the urban surroundings of each temperature station. Temporal variations are modeled according to weather conditions (such as wind speed, solar radiations, etc.) for different time scales : diurnal and nocturnal differences, daily variations and seasonal variations. The objective is to create a method which may be applied for any city in France. Geographical indicators are then calculated with OrbisGIS software from geographical data which are homogeneous and available at the french territory scale. Wheather conditions are recorded by MeteoFrance stations, which follow the same standard for the measurement of climatic parameters all around France. Climatic data analysis and modeling are performed with Python language using libraries such as Pandas and StatsModels. Modeled established according to the Nantes temperature dataset are verificated according to new air temperature networks implemented in the city of Nantes as well as other cities of west France (Angers, La Roche-sur-Yon).

scholarly journals Integrated method for cities air temperature estimation

2016 ◽  
Author(s):  
Jérémy Bernard ◽  
Marjorie Musy ◽  
Isabelle Calmet ◽  
Erwan Bocher ◽  
Pascal Kéravec
Keyword(s):  
Air Temperature ◽  
Weather Conditions ◽  
Temporal Variations ◽  
Climatic Data ◽  
Integrated Method ◽  
Python Language ◽  
Spatial Differences ◽  
The Difference ◽  
Surrounding Areas ◽  
The City

Urban Heat Island (UHI) is defined as the air temperature difference between the city and its surrounding areas. This phenomenon varies spatially (depending on the type of urban fabric constituting each neighborhood) and temporally (depending on the time of the day, on the season and on the weather conditions). This contribution proposes a methodology to model the UHI spatially and temporally using simple models built with free and open sources softwares (orbisGIS and python language). Ten air temperature sensors have been implemented in several neighborhoods of the Nantes urban area (a west coast french conurbation). The difference of UHI is observed and modeled for each of those sites. Spatial differences are modeled according to geographical indicators characterizing the urban surroundings of each temperature station. Temporal variations are modeled according to weather conditions (such as wind speed, solar radiations, etc.) for different time scales : diurnal and nocturnal differences, daily variations and seasonal variations. The objective is to create a method which may be applied for any city in France. Geographical indicators are then calculated with OrbisGIS software from geographical data which are homogeneous and available at the french territory scale. Wheather conditions are recorded by MeteoFrance stations, which follow the same standard for the measurement of climatic parameters all around France. Climatic data analysis and modeling are performed with Python language using libraries such as Pandas and StatsModels. Modeled established according to the Nantes temperature dataset are verificated according to new air temperature networks implemented in the city of Nantes as well as other cities of west France (Angers, La Roche-sur-Yon).

scholarly journals Temporal variations in air pollution at two roundabouts in the city of Cotonou, Benin

2021 ◽  
Author(s):  
Karine L.M. Codjo-Seignon ◽  
Vincentia M.C. Houssou ◽  
Philippe Kossolou ◽  
Ghislain E. Sopoh ◽  
Martin P. Aina
Keyword(s):  
Air Pollution ◽  
Electrochemical Sensors ◽  
Temporal Variations ◽  
World Health ◽  
Volatile Organic ◽  
Positive Linear Correlation ◽  
Solar Powered ◽  
Health Organization ◽  
The City ◽  
Background Air

Background: Air pollution has caused health and environmental problems around the world. In this study we analysed the temporal evolution of air pollution in Cotonou regarding the standards of Benin and of World Health Organization (WHO). Methods: Solar-powered electrochemical sensors (CO: carbon monoxide, SO2: sulphur dioxide, and O3/NO2: ozone/nitrogen dioxide) and photoionization detectors (for NMVOC: nonmethane volatile organic compounds) were permanently installed and monitored from June 2019 to March 2020 at Akpakpa PK3 (A) and Vèdokô Cica-Toyota (B) roundabouts.Results: CO and SO2 concentrations at both roundabouts were significantly higher on weekends than on weekdays. The concentrations of NMVOC and O3 / NO2 on Sunday differed considerably from the other days of the week at A and B, respectively. There was a positive linear correlation between the concentrations of CO and SO2, O3 / NO2 and SO2, and CO O3 / NO2 to B, and only between CO and O3 / NO2, in A.At the two sites, the average of SO2 concentrations (in μg/m3) were higher than the WHO standard (500) for an exposure of 10 minutes (2258 A and 2143 B) and the Benin standard (1300) for 1 hour exposure (2181 in A and 2092 in B).Conclusion: Air pollution varies in hours and days in Cotonou. Standards are respected, except for SO2. Particular attention should be paid to the concentrations and the possible sources of gas. More sophisticated monitoring system should be put in place.

scholarly journals Investigação de Ilhas de Calor em Brasília: Análise Multitemporal com Enfoque na Cobertura do Solo (Investigation of Heat Islands in Brasilia: Multi-Temporal Analysis with Focus on Land Cover)

2015 ◽  
Vol 7 (6) ◽  
pp. 1044
Author(s):  
Nickolas Castro Santana
Keyword(s):  
Urban Areas ◽  
Urban Expansion ◽  
Urban Climate ◽  
Temporal Analysis ◽  
Climate Impacts ◽  
City Center ◽  
Heat Islands ◽  
Multi Temporal ◽  
Basic Characteristics ◽  
The City

As questões relacionadas com o clima urbano tem se intensificado a partir da crescente urbanização imposta pelo sistema de desenvolvimento vigente. Um dos problemas gerados são as Ilhas de Calor, um aquecimento da superfície que tende a se formar em centros de cidades onde há intensa urbanização, sendo que a cidade de Brasília possuí as características básicas para a formação das mesmas. Para detectar a formação das ilhas de calor em Brasília foram utilizadas quatro imagens termais do satélite Landsat – 5, de 1987 á 2011. A partir da análise dos mapas de temperatura superficial foi possível perceber o constante aumento das temperaturas e abrangência das ilhas de calor em Brasília, fato este influenciado pela expansão urbana e intensificação do uso urbano, outro grande foco de calor foram as áreas de solo exposto que se apresentaram em certos casos com temperaturas maiores até mesmo que o centro da cidade, percebe-se portanto a necessidade de uma melhor gestão e planejamento das áreas urbanas para minimizar os impactos climáticos que tendem a se tornar cada vez mais significativos.    A B S T R A C T Issues related to urban climate has intensified from increasing urbanization imposed by the current development system. One of the problems generated are the heat islands, a warming of the surface that tends to form in city centers where there is intense urbanization, and the city of Brasilia possess the basic characteristics for forming the same. To detect the formation of heat islands in Brasilia the research used four thermal images of Landsat - 5, 1987 to 2011. Based on the analysis of the maps of temperature was possible to perceive the rising temperatures and breadth of heat islands in Brasilia, this fact influenced by urban expansion and intensification of urban use, another major focus of heat were the areas of exposed soil that performed in some cases with even higher temperatures than the city center, so realizes the need for better management and planning of urban areas to minimize climate impacts that are likely to become increasingly significant.   Keywords: Heat Islands; Thermal Sensor; Brasília; Land Use;  

scholarly journals Heavy Metal Accumulation in Shrubs Used in Roadside Planting

2020 ◽  
Keyword(s):  
Heavy Metals ◽  
Air Pollution ◽  
Heavy Traffic ◽  
Emission Spectrometry ◽  
City Center ◽  
Shrub Species ◽  
Platycladus Orientalis ◽  
Buxus Sempervirens ◽  
The City ◽  
Cu And Zn

<p>The aim of this study is to determine the shrub species which can be used as the biomonitor of air pollution originating mainly from the traffic and could provide the opportunity to increase the air quality in urban areas. To this end, Berberis thunbergii, Buxus sempervirens, Juniperus horizontalis, and Platycladus orientalis, mostly preferred species for roadside plantations, were chosen for the study. First, three regions with heavy traffic intensities were determined. Next, the levels of 4 heavy metals were examined by using Inductively Coupled Plasma–Optical Emission Spectrometry. The results obtained indicate that since the deposition of Cu and Zn is more in the leaves and barks of four species, these shrub species are more effective in the accumulation of Cu and Zn. Furthermore, the results of the study show that Platycladus orientalis is more effective in Cu and Pb accumulation, while Buxus sempervirens is more effective in terms of Ni and Zn accumulation. Determining high levels of traffic-originated heavy metals of Cu, Pb and Zn, particularly in the leaves of Platycladus orientalis in the city center indicates that air pollution is more intense in the city center and that Platycladus orientalis can be used as a biomonitor for traffic-originated air pollution.</p>

scholarly journals Phytoplankton diversity of a de-mineralized subtropical reservoir of Meghalaya state, northeast India

2021 ◽  
Vol 4 (3) ◽  
pp. 233-249
Author(s):  
Bhushan Kumar Sharma ◽  
Sumita Sharma
Keyword(s):  
Abiotic Factors ◽  
Diversity Indices ◽  
Temporal Variations ◽  
Northeast India ◽  
Phytoplankton Diversity ◽  
Spatial Differences ◽  
Species Diversity Indices ◽  
Specialist Species ◽  
The Individual

This study monitors the spa-tio-temporal variations of phytoplankton of a soft-water and de-mineralized reservoir of Meghalaya state of northeast India. Phyto-plankton assemblages of the littoral and limnetic regions reveal total 36 species and diverse desmids, and con-tribute dominantly to net plankton abundance. Our results record the quantita-tive importance of Charo-phyta > Bacillariophyta > Dinophyta and Charophyta > Dinophyta, and the ‘spe-cialist’ nature of 11 and six species at the littoral and limnetic regions, respective-ly. Staurastrum spp. and Cosmarium spp. are notable taxa. Phytoplankton indi-cates moderate species di-versity and depicts domi-nance and evenness varia-tions. The individual abiotic factors exert differential in-fluence on various taxa at the two regions and the ca-nonical correspondence analysis registers 73.02 and 71.14% cumulative influ-ence of 10 abiotic factors on the littoral and limnetic as-semblages, respectively. The spatial differences of phytoplankton composition, richness, abundance, im-portant groups and taxa, specialist species, diversity indices and the influence of individual abiotic factors are hypothesised to habitat heterogeneity amongst the sampled regions. This study records notable temporal differences of phytoplank-ton richness, abundance, di-versity and the role of abiot-ic factors vis-a-vis the lim-ited survey of November 1990–October 1991.

scholarly journals Car Free Zone as Planning Vision to Enhancements Transportation in City Centers (Holy Najaf City Center-Iraq)

2022 ◽  
Vol 961 (1) ◽  
pp. 012074
Author(s):  
Zahraa Saeb Mohialdeen ◽  
Mustafa Abduljalil Ebrageem
Keyword(s):  
Air Pollution ◽  
Public Transportation ◽  
Research Problem ◽  
Transportation System ◽  
Easy Access ◽  
City Center ◽  
Pedestrian Movement ◽  
Free Zone ◽  
The City ◽  
Holy City

Abstract The idea of a car-free city represents a solution to the problem of fuel consumption and air pollution caused by the use of cars and replaces the idea of owning and using private cars with an efficient transportation system, and it doesn’t mean living without cars, because cars have become an integral part of a modern city. On the contrary, people can still drive in city but will not park their cars at home. Instead, they park elsewhere on their way home. Research problem: Weak regulation of the movement of vehicles in the center of the holy city of Najaf, which leads to the danger of pedestrian movement in the city center. The aim of the research: to provide a safe and effective movement for pedestrians in the center of the holy city of Najaf. Research hypothesis: The use of the car-free zone strategy in the city center transportation system achieves security for the population in the old city. The research examines reasons behind suggesting free-of-vehicle areas It gives a number of policies to achieve the strategy in the center of the holy city of Najaf, including the provision of public transportation, furniture and comfort for pedestrians in the streets, as well as easy access for the residents of the area. Thus, it is possible to draw the conclusion that there is a possibility to achieve this strategy in religious centers according to a number of policies that suit the specificity of the area.

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