Carbon dioxide emissions variability monitoring, based on four years of Eddy Covariance measurements in a typical Mediterranean city

2021 ◽  
Author(s):  
Konstantinos Politakos ◽  
Stavros Stagakis ◽  
Nektarios Chrysoulakis
Keyword(s):  
Time Series ◽  
Eddy Covariance ◽  
Carbon Dioxide Emissions ◽  
Source Area ◽  
Urban Morphology ◽  
City Centre ◽  
Surface Model ◽  
Time Step ◽  
The City ◽  
Mediterranean City

<p>Urban areas around the globe are growing rapidly and as a consequence the anthropogenic effects on the environment are ever-increasing. Understanding the dynamics, procedures and mechanics behind urban greenhouse gas emissions is a challenge for the scientific community. This study investigates the variability of urban CO<sub>2</sub> emissions in the city centre of Heraklion, a typical Mediterranean city in Greece, during a four-year period with gradual changes in the traffic regulations and changes in traffic patterns due to the recent restriction measures imposed to limit the spread of the COVID-19 pandemic. The CO<sub>2</sub> flux (Fc) was measured using the Eddy Covariance (EC) method with a single tower-based system, permanently installed in the centre of the city. Fc was calculated at a 30-min time step and the time-series were quality-controlled and gap-filled using a moving look-up table (mLUT) technique. Fc time series were then aggregated to monthly and yearly emissions totals. Annual flux source area was estimated with the Flux Footprint Prediction (FFP) model, parameterized using measured atmospheric parameters and urban morphological parameters extracted from a Digital Surface Model. The source area was characterized by complex urban morphology and land use types. Specifically, at North of the tower a commercial zone is located, where significantly higher Fc patterns were detected, compared to South, where a residential area dominates. A gradual reduction to CO<sub>2</sub> emissions has been observed since 2016, due to urban planning interventions related to pedestalization of extended areas in the city centre and traffic regulation. During the COVID-19 lockdown period in the Spring of 2020, the diurnal Fc patterns and the monthly aggregated Fc showed significant reductions in the order of 70 % compared to the previous years. Fc values returned to the previous years’ levels with the end of the lock-down in the summer 2020, as it was expected. Finally, during the second lock-down, started in Greece in November 2020, the CO<sub>2</sub> emissions were higher compared to the first lock-down, reflecting a higher level of mobility in Heraklion centre.</p>

scholarly journals Extraction of Urban Information for Seismic Hazard and Risk Assessment in Lima, Peru Using Satellite Imagery

2013 ◽  
Vol 8 (2) ◽  
pp. 328-345 ◽  
Author(s):  
Masashi Matsuoka ◽  
◽  
Hiroyuki Miura ◽  
Saburoh Midorikawa ◽  
Miguel Estrada ◽  
...  
Keyword(s):  
Time Series ◽  
Large Scale ◽  
Surface Model ◽  
Building Inventory ◽  
Hazard And Risk ◽  
Hazard And Risk Assessment ◽  
Landsat Satellite ◽  
Time Series Images ◽  
The City ◽  
Area Data

Lima City, Peru, is, like Japan, on the verge of a strike by a massive earthquake. Building inventory data for the city need to be created for earthquake damage estimation, so the city was subjected to the extraction of spatial distribution of building age from Landsat satellite time-series images and an assessing building height from ALOS/PRISM images. Interband calculation of Landsat time-series images gives various indices relevant to land covering. The transition of indices was evaluated to clarify urban sprawl taking place in the northern, southern, and eastern parts of Lima City. Built-up area data were created for buildings by age. The height of large-scale mid-to-highrise buildings was extracted by applying spatial filtering for a DSM (Digital Surface Model) generated from stereovision PRISM images. As a result, buildings with a small square measure, color similar to that of their surroundings, or complicated shapes turned out to be difficult to detect.

Sea level rise in the Venetian lagoon inferred from the 150-year-long tidal record

2020 ◽  
Author(s):  
Sara Rubinetti ◽  
Carla Taricco ◽  
Davide Zanchettin ◽  
Enrico Arnone ◽  
Angelo Rubino
Keyword(s):  
Time Series ◽  
Sea Level Rise ◽  
Sea Level ◽  
City Centre ◽  
Reference Level ◽  
Decadal Scale ◽  
Historical Series ◽  
Venetian Lagoon ◽  
The City

<p>The city of Venice (Northern Italy), together with its lagoon, is a historic, cultural and artistic heritage of inestimable value. One of its peculiarities consists in the recurrent storm surge phenomena, referred to as <em>acqua alta</em>. Sea level rise and local subsidence made their frequency to increase dramatically with respect to the past, causing severe damages to the lagoon and in particular to the city centre, as during the exceptional high tide verified on November 12, 2019.<br>Here we show the analysis of the historical time series of tidal maxima and minima recorded in the Venetian lagoon, covering the period 1872-2018. It is the longest and most complete historical series of the Venetian area and one of the longest records of the entire Mediterranean region. During this period, the relative sea level height has increased of about 30 cm with respect to the reference level, while the average number of <em>acqua alta</em> events – evaluated over a 40-year time interval - has passed from about 4 to 70 per year. These events usually occur during the fall season (from October to December), even if a not negligible number has been also recorded during winter. Therefore, we analyse the October-March average annual time series with advanced spectral analysis methods, like Monte Carlo Singular Spectrum Analysis (MC-SSA), to extract and reconstruct the significant variability modes characterizing the record. They are the increasing long-term trend and components with multidecadal, decadal and interannual periods. The trend results from the superposition on the global eustacy of the local subsidence affecting the Venetian lagoon, which is due to both natural causes and human activities. We also discuss the possible linkage of the other significant spectral components to large scale climatic patterns. In particular, the decadal-scale oscillation is one of the most important variability modes affecting Northern Italian hydrology.<br>Finally, we apply simple statistical methods (autoregressive models and feed-forward neural networks) to forecast the long-term evolution of sea level over the next ten years. In this contribution, we illustrate results from this state of the art two-fold statistical prediction system that provides robust predictions of sea level in the Venetian lagoon for the next decade and discuss them in the light of current longer-term projections of future sea level rise. Finally, we will test the predictive skill of the applied methods using tidal measurements recorded during 2019, to verify if our predictions are able to describe tidal variability characterizing the current year.       </p>

scholarly journals Eddy covariance measurements of the net turbulent methane flux in the city centre – results of 2 years campaign in Łódź, Poland

2016 ◽  
Author(s):  
W. Pawlak ◽  
K. Fortuniak
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Vertical Component ◽  
Ground Level ◽  
Methane Flux ◽  
City Centre ◽  
Carbon Dioxide Fluxes ◽  
Methane Fluxes ◽  
Eddy Covariance Measurements ◽  
The City

Abstract. In the period between July 2013 and August 2015, continuous measurements of turbulent methane exchange between an urbanised area and the atmosphere were carried out in Łódź. Such long, continuous measurement series of turbulent methane exchange between the city and the atmosphere are still a rarity. The measurement station was located in the centre of the city, where fluxes of energy (sensible and latent heat) and fluxes of mass (carbon dioxide) have been continuously measured since 2000 and 2007, respectively. In the immediate vicinity of the measurement station there are potential sources of methane, such as streets with vehicle traffic or dense sewerage and natural gas networks. To determine the fluxes, the eddy covariance technique was used; the measurement station was equipped with instruments for recording fluctuations in the vertical component of the wind speed (an ultrasonic 3D anemometer, RM Young 81000, RM Young, USA) as well as the concentration of methane in the air (an open path Li 7700 CH4 Analyser, Li-cor, USA). The devices were mounted on a mast at a height of 37 metres above ground level and, on average, 20 metres over the roofs of the surrounding buildings. The results were therefore averaged for an area with a diameter of approximately 1 kilometre. Our aim was to investigate the temporal variability of the turbulent exchange of methane in the city-atmosphere system. The results show in the first place that positive methane fluxes (turbulent gas transport from the surface to the atmosphere) definitely dominate compared with negative fluxes. This indicates that the study area of the centre of Łódź is a net source of methane to the troposphere. The measurements also indicated the existence of a clear annual rhythm of the turbulent flux of methane in the centre of Łódź (on average, the values observed in winter amounted to ~40–60 nmol m−2 s−1 and were significantly larger than in summer). The daily variability of the flux of CH4 (FCH4) is faintly visible throughout the year. The studied area of the centre of Łódź is also characterised by a cycle of methane exchange – the values measured on working days were higher by 6.6 % (winter) to 5.6 % (summer) than those observed at weekends. The largest monthly exchange was characteristic of winter months (from 2.0 to 2.7 g m−2 month−1) and the lowest occurred in summer (from 0.8 to 1.0 g m−2 month−1). The mean daily patterns of FCH4 in consecutive months were used to determine the cumulative annual exchange. In 2014, the centre of Łódź emitted a net quantity of almost 18 g m−2. Furthermore, the study analyses the covariability of methane and carbon dioxide fluxes.

scholarly journals Urban Mobility Demand Profiles: Time Series for Cars and Bike-Sharing Use as a Resource for Transport and Energy Modeling

Data ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 108 ◽  
Author(s):  
Noussan ◽  
Carioni ◽  
Sanvito ◽  
Colombo
Keyword(s):  
Time Series ◽  
Traffic Monitoring ◽  
Transport Sector ◽  
High Temporal Resolution ◽  
Urban Mobility ◽  
Time Step ◽  
Transport Models ◽  
Bike Sharing ◽  
Urban Contexts ◽  
The City

The transport sector is currently facing a significant transition, with strong drivers includingdecarbonization and digitalization trends, especially in urban passenger transport. The availability ofmonitoring data is at the basis of the development of optimization models supporting an enhancedurban mobility, with multiple benefits including lower pollutants and CO2 emissions, lower energyconsumption, better transport management and land space use. This paper presents two datasetsthat represent time series with a high temporal resolution (five-minute time step) both for vehiclesand bike sharing use in the city of Turin, located in Northern Italy. These high-resolution profileshave been obtained by the collection and elaboration of available online resources providing liveinformation on traffic monitoring and bike sharing docking stations. The data are provided for theentire year 2018, and they represent an interesting basis for the evaluation of seasonal and dailyvariability patterns in urban mobility. These data may be used for different applications, rangingfrom the chronological distribution of mobility demand, to the estimation of passenger transportflows for the development of transport models in urban contexts. Moreover, traffic profiles are at thebasis for the modeling of electric vehicles charging strategies and their interaction with the powergrid.

Spatiotemporal dynamics of CO2 flux in Basel city centre

2021 ◽  
Author(s):  
Stavros Stagakis ◽  
Christian Feigenwinter ◽  
Etienne Zurbriggen ◽  
Andrea Pitacco ◽  
Roland Vogt
Keyword(s):  
Soil Respiration ◽  
Eddy Covariance ◽  
City Centre ◽  
Urban Vegetation ◽  
Emission Sources ◽  
Flux Dynamics ◽  
Mitigation Potential ◽  
Eddy Covariance Measurements ◽  
Plant Respiration ◽  
The City

<p>Independent, timely and accurate monitoring of urban CO<sub>2</sub> emissions is important to assess the progress towards the Paris Agreement goals, evaluate the mitigation potential of the implemented actions and support urban planning, policy- and decision-making processes. However, there are several challenges towards achieving comprehensive urban emission monitoring at the required scales, which are mainly related to the complexities in the urban form, the urban function and their interactions with the atmosphere. Cities are highly heterogeneous mosaics of CO<sub>2</sub> sources and sinks. Typically, the main emission sources in an urban neighbourhood are vehicles and buildings, while the contribution of human, plant and soil respiration can be also significant depending on population density and green area fraction. At the same time, urban vegetation acts as carbon sink, mitigating urban emissions locally. This study attempts to unravel the complex urban CO<sub>2</sub> flux dynamics by modelling each component separately (i.e. building emissions, traffic emissions, human metabolism, photosynthetic uptake, plant respiration, soil respiration) based on high resolution geospatial, meteorological and population activity datasets. The case study is the city centre of Basel, Switzerland. The models are calibrated and evaluated using Eddy Covariance measurements of CO<sub>2</sub> flux from two permanent tower sites in the city centre, covering a significant part of the study area. Moreover, an extended field campaign for the measurement of the biogenic components (i.e. photosynthetic uptake, plant respiration, soil respiration) has been active since the summer of 2020, involving regular chamber flux measurements and soil stations across the study area. The study reveals the spatial and temporal complexity of the urban CO<sub>2</sub> flux dynamics both diurnally and seasonally. The relative contribution of each flux component to the seasonal cycle is presented, while the mitigation potential of urban vegetation is evaluated. Cross-comparison between model outputs and Eddy Covariance measurements are discussed in respect to source area variability, airflow complexity in the urban canopy layer and irregular unrecognized emission sources.</p>

Modelling the Urban Boundary-Layer Over a Typical Mediterranean City Using WRF: Assessment of UHI and Thermal Comfort

2014 ◽  
Author(s):  
M.-V. Guarino ◽  
A. Martilli ◽  
S. Di Sabatino ◽  
L. S. Leo
Keyword(s):  
Thermal Stress ◽  
Thermal Comfort ◽  
Building Materials ◽  
Model Performance ◽  
Wrf Model ◽  
City Centre ◽  
Medium Size ◽  
Urban Structure ◽  
The City ◽  
Mediterranean City

The aim of this work is to simulate the Urban Heat Island (UHI) in a medium size Mediterranean city (Lecce, IT) and to analyze its consequences for thermal comfort. We use the Weather Research and Forecasting (WRF) model (version 3.2), that accounts for the urban structure with a multilayer urban parameterization (BEP+BEM i.e. the Building Effect Parameterization (BEP) combined with the Building Energy Model (BEM)). Three hot and cloudless summer days have been simulated and results have been compared with field data collected during an experimental campaign performed over the whole summer in the city of Lecce, Italy. In the model, the structure and shape of the city are reproduced using detailed data related to different urban classes, urban fraction and building morphometry. For the residential urban classes, different thermal parameters that are representative of building materials in the oldest and the newer part of the city, are used. Results show that UHI reaches, on average, its maximum intensity (4–5 °C) just before sunrise, and its minimum (2 °C) occurs during the day. Model validation inferred through statistical analysis shows overall a better model performance for the historical city centre than for the suburban area. This suggests that further refinement of the building representation in the outskirts might still be required. Consequences of the increased urban temperature are evaluated in terms of thermal comfort. The maximum thermal stress occurs during the central hours of the day, while, the minimum thermal stress occurs during the twilight hours.

scholarly journals Direct determination of highly size-resolved turbulent particle fluxes with the disjunct eddy covariance method and a 12 – stage electrical low pressure impactor

2008 ◽  
Vol 8 (3) ◽  
pp. 8997-9034 ◽  
Author(s):  
A. Schmidt ◽  
O. Klemm
Keyword(s):  
Eddy Covariance ◽  
Aerosol Particles ◽  
Direct Determination ◽  
Low Pressure ◽  
West Germany ◽  
City Centre ◽  
Eddy Covariance Method ◽  
North West ◽  
Particle Fluxes ◽  
The City

Abstract. During summer 2007, turbulent vertical particle fluxes were measured for a period of 98 days near the city centre of Münster in north-west Germany. For this purpose, a valve controlled disjunct eddy covariance system was mounted at 65 m a.g.l. on a military radio tower. The concentration values for 11 size bins with aerodynamic diameters (D50) from 0.03 to 10 μm were measured with an electrical low pressure impactor. After comparison with other fluxes obtained from 10 Hz measurements with the classical eddy covariance method, the loss of information concerning high frequent parts of the flux could be stated as negligible. The results offer an extended insight in the turbulent atmospheric exchange of aerosol particles by highly size-resolved particle fluxes covering 11 size bins and show that the city of Münster acts as a relevant source for aerosol particles. Significant differences occur between the fluxes of the various particle size classes. While the total particle number flux shows a pattern which is strictly correlated to the diurnal course of the turbulence regime and the traffic intensity, the total mass flux exhibits a single minimum in the evening hours when coarse particles start to deposit. As a result, a mean mass deposition of about 10 g m−2 per day was found above the urban test site, covering the aerosol size range from 40 nm to 2.0 μm. By contrast, the half-hourly total number fluxes accumulated over the lower ELPI stages range from –4.29×107 to +1.44×108 particles m−2 s-1 and are clearly dominated by the sub-micron particle fraction of the impactor stages with diameters between 40 nm and 320 nm. The averaged number fluxes of particles with diameters between 2.0 and 6.4 μm show lower turbulent dynamics during daytime and partially remarkably high negative fluxes with mean deposition velocities of 2×10−3 m s−1 that appear temporary during noontime and in the evening hours.

scholarly journals Designing an Environmental Zone in a Mediterranean City to Support City Logistics

2018 ◽  
Vol 6 (1) ◽  
pp. 1 ◽  
Author(s):  
Lorenzo Ros-McDonnell ◽  
María Victoria De-la-Fuente-Aragon ◽  
Diego Ros-McDonnell ◽  
Manuel Cardós Carboneras
Keyword(s):  
Air Pollution ◽  
Traffic Congestion ◽  
City Centre ◽  
City Logistics ◽  
European Directives ◽  
European Cities ◽  
The City ◽  
Mediterranean City ◽  
Historical Centre

<p>European cities are facing enormous challenges in accessibility and livability terms due to several European directives, which are compulsory in the mid/long term, traffic congestion levels are still increasing, and air pollution and noise disturbs citizens’ lives. This work presents the study carried out in a Mediterranean city to define an Environmental Zone with traffic restrictions for vehicles in the historical centre of the city of Cartagena (Spain) by exploring different urban logistics measures to tackle main problems caused by freight deliveries and pickups in the city centre. These solutions aimed to enhance the efficiency of vehicles, and to reduce both traffic congestion the environmental impacts caused by freight delivery in the city in order to improve urban sustainability.</p>

scholarly journals Eddy covariance measurements of the net turbulent methane flux in the city centre – results of 2-year campaign in Łódź, Poland

2016 ◽  
Vol 16 (13) ◽  
pp. 8281-8294 ◽  
Author(s):  
Włodzimierz Pawlak ◽  
Krzysztof Fortuniak
Keyword(s):  
Eddy Covariance ◽  
Methane Flux ◽  
Heat Fluxes ◽  
City Centre ◽  
Carbon Dioxide Fluxes ◽  
Surface Exchange ◽  
Eddy Covariance Measurements ◽  
The City ◽  
Comparable Magnitude ◽  
Measurement Period

Abstract. To investigate temporal variability of methane (CH4) fluxes in an urban environment, air–surface exchange fluxes of CH4 were continuously measured using eddy covariance techniques at a city-centre site in Łódź, Poland, from July 2013 to August 2015. In the immediate vicinity of the measurement site, potential methane sources include vehicle traffic, dense sewerage infrastructure and natural gas networks. Sensible and latent heat fluxes have also been measured since 2000 and carbon dioxide fluxes since 2007 at this site. Upward CH4 fluxes dominated during the measurement period, indicating that the city centre is a net source of CH4 to the troposphere. The highest monthly fluxes were observed in winter (2.0 to 2.7 g m−2 month−1) and the lowest in summer (0.8 to 1.0 g m−2 month−1). Fluxes on working days were around 6 % higher than on weekends. The cumulative flux indicates that the city centre emitted a net quantity of nearly 18 g m−2 of CH4 in 2014. Stable values of the FCO2∕ FCH4 ratio in months (minimum 2.41 × 10−3, maximum 5.3 × 10−3) and the lack of a clear annual course suggest comparable magnitude of both fluxes.

scholarly journals Direct determination of highly size-resolved turbulent particle fluxes with the disjunct eddy covariance method and a 12 – stage electrical low pressure impactor

2008 ◽  
Vol 8 (24) ◽  
pp. 7405-7417 ◽  
Author(s):  
A. Schmidt ◽  
O. Klemm
Keyword(s):  
Eddy Covariance ◽  
Aerosol Particles ◽  
Direct Determination ◽  
Low Pressure ◽  
West Germany ◽  
City Centre ◽  
Eddy Covariance Method ◽  
North West ◽  
Particle Fluxes ◽  
The City

Abstract. During summer 2007, turbulent vertical particle mass and number fluxes were measured for a period of 98 days near the city centre of Münster in north-west Germany. For this purpose, a valve controlled disjunct eddy covariance system was mounted at 65 m a.g.l. on a military radio tower. The concentration values for 11 size bins with aerodynamic diameters (D50) from 0.03 to 10 μm were measured with an electrical low pressure impactor. After comparison with other fluxes obtained from 10 Hz measurements with the classical eddy covariance method, the loss of information concerning high frequent parts of the flux could be stated as negligible. The results offer an extended insight in the turbulent atmospheric exchange of aerosol particles by highly size-resolved particle fluxes covering 11 size bins and show that the city of Münster acts as a relevant source for aerosol particles. Significant differences occur between the fluxes of the various particle size classes. While the total particle number flux shows a pattern which is strictly correlated to the diurnal course of the turbulence regime and the traffic intensity, the total mass flux exhibits a single minimum in the evening hours when coarse particles start to deposit. As a result, a mean mass deposition of about 10 mg m−2 per day was found above the urban test site, covering the aerosol size range from 40 nm to 2.0 μm. By contrast, the half-hourly total number fluxes accumulated over the lower ELPI stages range from −4.29×107 to +1.44×108 particles m−2 s−1 and are clearly dominated by the sub-micron particle fraction of the impactor stages with diameters between 40 nm and 320 nm. The averaged number fluxes of particles with diameters between 2.0 and 6.4 μm show lower turbulent dynamics during daytime and partially remarkably high negative fluxes with mean deposition velocities of 2×10−3 m s−1 that appear temporary during noontime and in the evening hours.

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