scholarly journals Trends in rainfall associated with sources of air pollution

2008 ◽  
Vol 5 (3) ◽  
pp. 184 ◽  
Author(s):  
E.Keith Bigg
Keyword(s):  
Urban Areas ◽  
Daily Rainfall ◽  
Gold Coast ◽  
Cloud Formation ◽  
Urban Centers ◽  
Water Shortages ◽  
Surface Moisture ◽  
Cloud Properties ◽  
Rain Formation

Environmental context. Decreasing trends in rainfall over large areas of eastern and south-western Australia have resulted in critical water shortages. Three reasons have been suggested. The first is a change in atmospheric circulation as a result of greenhouse gas forcing. The second is that changes in land usage have affected surface moisture, albedo and cloud formation. Another, the subject of this study, is that airborne particulates associated with urban areas have acted to decrease the mean efficiency of rainfall, the growth of urban areas thereby causing an underlying decreasing trend in rainfall. Abstract. Trends in rainfall in the 35 years 1970–2004 have been calculated for all 350 available rainfall stations having sufficiently complete records that lie between latitudes 26–30°S and longitudes 150–154°E. The area contains two major urban centers, Brisbane with a rapidly growing population approaching two million and the Gold Coast with a population of ~500 000. Statistically highly significant negative trends were found in the vicinity of Brisbane, with decreases exceeding 40% of mean daily rainfall in the 35 years, and in a smaller area inland from the Gold Coast. The spatial distribution of trends was consistent with aerosol production from human activities, the prevailing winds and losses due to the topography. A previously published observation using satellite data showed that cloud properties were affected by urban aerosols in a way that is likely to reduce precipitation. The results of this study reinforce the suggestion made then that monitoring of aerosol concentrations and properties and in-situ observations of rain formation processes in the area should be undertaken as a matter of urgency.

Methane Estimates in the Northeastern US using Continuous Measurements from a Regional Tower Network

2020 ◽  
Author(s):  
Kimberly Mueller ◽  
Subhomoy Ghosh ◽  
Anna Karion ◽  
Sharon Gourdji ◽  
Israel Lopez-Coto ◽  
...  
Keyword(s):  
Natural Gas ◽  
Urban Areas ◽  
The United States ◽  
Ch4 Emission ◽  
Urban Centers ◽  
Ch4 Emissions ◽  
The Us ◽  
Spatio Temporal ◽  
Northeast Us

<p>In the past decade, there has been a scientific focus on improving the accuracy and precision of methane (CH4) emission estimates in the United States, with much effort targeting oil and natural gas producing basins. Yet, regional CH4 emissions and their attribution to specific sources continue to have significant associated uncertainties. Recent urban work using aircraft observations have suggested that CH4 emissions are not well characterized in major cities along the U.S. East Coast; discrepancies have been attributed to an under-estimation of fugitive emissions from the distribution of natural gas. However, much of regional and urban research has involved the use of aircraft campaigns that can only provide a spatio-temporal snapshot of the CH4 emission landscape. As such, the annual representation and the seasonal variability of emissions remain largely unknown. To further investigate CH4 emissions, we present preliminary CH4 emissions estimates in the Northeastern US as part of NIST’s Northeast Corridor (NEC) testbed project using a regional inversion framework. This area encompasses over 20% of the US and contains many of the dominant CH4 emissions sources important at both regional and local scales.  The atmospheric inversion can estimate sub-monthly 0.1-degree emissions using observations from a regional network of up to 37 in-situ towers; some towers are in non-urban areas while others are in cities or suburban areas. The inversion uses different emission products to help provide a prior constraint within the inversion including anthropogenic emissions from both the EDGAR v42 for the year 2008 and the US EPA for the year 2012, and natural wetland CH4 emissions from the WetCHARTs ensemble mean for the year 2010. Results include the comparison of synthetic model simulated CH4 concentrations (i.e., convolutions of the emission products with WRF-STILT footprints + background) to mole-fractions measured at the regional in-situ sites. The comparison provides an indication as to how well our prior understanding of emissions and incoming air flow matches the atmospheric signatures due to the underlying CH4 sources.  We also present a preliminary set of CH4 fluxes for a selected number of urban centers and discuss challenges estimating highly-resolved methane emissions using high-frequency in-situ observations for a regional domain (e.g. few constraints, skewness in underlying fluxes, representing incoming background, etc.). Overall, this work provides the basis for a year-long inversion that will yields regional CH4 emissions over the Northeast US with a focus on Eastern urban areas.</p>

scholarly journals A Study of UVER in Santiago, Chile Based on Long-Term In Situ Measurements (Five Years) and Empirical Modelling

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 368
Author(s):  
Lisdelys González-Rodríguez ◽  
Amauri Pereira de Oliveira ◽  
Lien Rodríguez-López ◽  
Jorge Rosas ◽  
David Contreras ◽  
...  
Keyword(s):  
Urban Areas ◽  
Solar Spectrum ◽  
Sun Exposure ◽  
Great Accuracy ◽  
In Situ Measurements ◽  
Uv Index ◽  
Empirical Modelling ◽  
The People

Ultraviolet radiation is a highly energetic component of the solar spectrum that needs to be monitored because is harmful to life on Earth, especially in areas where the ozone layer has been depleted, like Chile. This work is the first to address the long-term (five-year) behaviour of ultraviolet erythemal radiation (UVER) in Santiago, Chile (33.5° S, 70.7° W, 500 m) using in situ measurements and empirical modelling. Observations indicate that to alert the people on the risks of UVER overexposure, it is necessary to use, in addition to the currently available UV index (UVI), three more erythema indices: standard erythemal doses (SEDs), minimum erythemal doses (MEDs), and sun exposure time (tery). The combination of UVI, SEDs, MEDs, and tery shows that in Santiago, individuals with skin types III and IV are exposed to harmfully high UVER doses for 46% of the time that UVI indicates is safe. Empirical models predicted hourly and daily values UVER in Santiago with great accuracy and can be applied to other Chilean urban areas with similar climate. This research inspires future advances in reconstructing large datasets to analyse the UVER in Central Chile, its trends, and its changes.

scholarly journals iBikeSafe: A Multi-Parameter System for Monitoring, Evaluation and Visualization of Cycling Paths in Smart Cities Targeted at Cycling Adverse Conditions

Smart Cities ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 1058-1086
Author(s):  
Franklin Oliveira ◽  
Daniel G. Costa ◽  
Luciana Lima ◽  
Ivanovitch Silva
Keyword(s):  
Urban Areas ◽  
Smart Cities ◽  
Large City ◽  
Health And Safety ◽  
Parameter System ◽  
Urban Centers ◽  
Adverse Conditions ◽  
Last Mile ◽  
Real Scenario

The fast transformation of the urban centers, pushed by the impacts of climatic changes and the dramatic events of the COVID-19 Pandemic, will profoundly influence our daily mobility. This resulted scenario is expected to favor adopting cleaner and flexible modal solutions centered on bicycles and scooters, especially as last-mile options. However, as the use of bicycles has rapidly increased, cyclists have been subject to adverse conditions that may affect their health and safety when cycling in urban areas. Therefore, whereas cities should implement mechanisms to monitor and evaluate adverse conditions in cycling paths, cyclists should have some effective mechanism to visualize the indirect quality of cycling paths, eventually supporting choosing more appropriate routes. Therefore, this article proposes a comprehensive multi-parameter system based on multiple independent subsystems, covering all phases of data collecting, formatting, transmission, and processing related to the monitoring, evaluating, and visualizing the quality of cycling paths in the perspective of adverse conditions that affect cyclist. The formal interactions of all modules are carefully described, as well as implementation and deployment details. Additionally, a case study is considered for a large city in Brazil, demonstrating how the proposed system can be adopted in a real scenario.

Toward CO2 and CH4 measurements by ground-based observations of surface-scattered sunlight

2021 ◽  
Author(s):  
Benedikt Hemmer ◽  
Christin Proß ◽  
Stanley P. Sander ◽  
Thomas J. Pongetti ◽  
Zhao-Cheng Zeng ◽  
...  
Keyword(s):  
Los Angeles ◽  
Urban Areas ◽  
Near Infrared ◽  
Chem Phys ◽  
Retrieval Algorithm ◽  
Los Angeles Basin ◽  
Satellite Measurements ◽  
Precise Knowledge ◽  
Extended Sources

<div> <div>Precise knowledge of sources and sinks in the carbon cycle is desired to understand its sensitivity to climate change and to account and verify man-made emissions. In this context, extended sources like urban areas play an important role. While in-situ measurements of carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) are highly accurate but localized, satellites measure column-integrated concentrations over an extended footprint. The CLARS-FTS [1, 2] stationed at the Mt. Wilson observatory looking downward into the Los Angeles basin has pioneered an innovative measurement technique that fills the sensitivity gap between in-situ and satellite measurements. The technique enables mapping the urban greenhouse gas concentration fields by collecting spectra of ground scattered sunlight and scanning through the region.</div> <div> </div> <div>Here, we report on progress developing a portable setup for a CLARS-FTS-like measurement geometry. The instrument is based on the EM27/SUN FTS with a modified pointing technique and a more sensitive detector. The retrieval algorithm is based on the RemoTeC software, previously employed for solar backscatter satellite measurements. We discuss first steps in terms of instrument performance and retrieval exercises. For the latter, we have carried out simulations on how the neglect of scattering by the retrieval affects the retrieved boundary layer concentrations of CO<sub>2</sub> and CH<sub>4</sub> for an ensemble of hypothetical scenes with variable complexity in aeorsol loadings and viewing geometry. We also report on a test to apply RemoTeC to a small set of CLARS-FTS spectra collected throughout the Los Angeles basin.</div> <div> </div> <div><em>References</em></div> <div>[1] Fu, D. et al., 2014: Near-infrared remote sensing of Los Angeles trace gas distributions from a mountaintop site, Atmos. Meas. Tech., 7, 713–729, https://doi.org/10.5194/amt-7-713-2014</div> [2] Wong, K. W. et al., 2015: Mapping CH4 : CO2 ratios in Los Angeles with CLARS-FTS from Mount Wilson, California, Atmos. Chem. Phys., 15, 241–252, https://doi.org/10.5194/acp-15-241-2015</div>

scholarly journals How Biased Is Aircraft Cloud Sampling?

2016 ◽  
Vol 33 (1) ◽  
pp. 185-189 ◽  
Author(s):  
Paul R. Field ◽  
Kalli Furtado
Keyword(s):  
Order Statistics ◽  
Sampling Strategy ◽  
Model Testing ◽  
Resource Limitations ◽  
Cloud Properties ◽  
Gamma Distributions

AbstractAircraft are the dominant method for in situ sampling of cloud properties. Resource limitations mean that aircraft tend to follow a sampling strategy when there is more than one cloud from which to choose. This can result in biased cloud statistics that are used for parameterization development and model testing. In this study, order statistics are used to estimate the potential magnitude of this bias when a strategy based on choosing the larger cloud is employed. It is found for cloud properties following gamma distributions that a typical bias of a factor of 1.5 can result when the larger of two clouds is repeatedly chosen for sampling.

scholarly journals Portable XRF Quick-Scan Mapping for Potential Toxic Elements Pollutants in Sustainable Urban Drainage Systems: A Methodological Approach

Sci ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 46
Author(s):  
Guri Venvik ◽  
Floris C. Boogaard
Keyword(s):  
Green Infrastructure ◽  
Urban Areas ◽  
Toxic Elements ◽  
Urban Drainage ◽  
Runoff Water ◽  
Portable Xrf ◽  
Potential Toxic Elements ◽  
Drainage Systems ◽  
Urban Drainage Systems

Sustainable urban drainage systems (SuDS) such as swales are designed to collect, store and infiltrate a large amount of surface runoff water during heavy rainfall. Stormwater is known to transport pollutants, such as particle-bound Potential Toxic Elements (PTE), which are known to often accumulate in the topsoil. A portable XRF instrument (pXRF) is used to provide in situ spatial characterization of soil pollutants, specifically lead (Pb), zink (Zn) and copper (Cu). The method uses pXRF measurements of PTE along profiles with set intervals (1 meter) to cover the swale with cross-sections, across the inlet, the deepest point and the outlet. Soil samples are collected, and the In-Situ measurements are verified by the results from laboratory analyses. Stormwater is here shown to be the transporting media for the pollutants, so it is of importance to investigate areas most prone to flooding and infiltration. This quick scan method is time and cost-efficient, easy to execute and the results are comparable to any known (inter)national threshold criteria for polluted soils. The results are of great importance for all stakeholders in cities that are involved in climate adaptation and implementing green infrastructure in urban areas. However, too little is still known about the long-term functioning of the soil-based SuDS facilities.

scholarly journals An evaluation of the self-help housing scheme in Botswana, case of Gaborone city

Spatium ◽  
2007 ◽  
pp. 28-36 ◽  
Author(s):  
Horatio Ikgopoleng ◽  
Branko Cavric
Keyword(s):  
Low Income ◽  
Urban Areas ◽  
Urban Families ◽  
Evaluation Study ◽  
Urban Housing ◽  
Urban Centers ◽  
Self Help ◽  
Housing Scheme ◽  
The Government ◽  
The Impact

Botswana like other developing countries faces a problem of acute shortage of housing, particularly for low-income urban families. The current housing problems are the outcomes of the economic, demographic and social changes which the country has experienced since independence in 1966. In particular the urbanization process which surfaced in the early 1980?s. The government has sought to cope with the problem of low-income urban housing by establishing a Self-Help Housing (SHHA) program in the main urban centers. The evaluation findings reveal that, on the whole, the impact of the SHHA approach on the improvement of low-income urban housing has been unsuccessful. The major problems of the scheme are lack of serviced land and inadequate finances for plot development. This has been exacerbated by the high urban development standards which are out of the reach of low-income urban families. The evaluation study also reveals that, there are some indications of non low-income urban households living in SHHA areas. The available evidence reveals that the number of those people in SHHA areas is not as big as has been speculated by most people in the country. However this paper calls for more investigation in this issue and a need for more tight measures to control this illicit practice. The major conclusions are that housing policies in Botswana are not supportive of the general housing conditions in low-income urban areas. Therefore there is a need for urban planners and policy makers of Botswana to take more positive action towards the improvement of low-income urban areas. This would require pragmatic policies geared towards the improvement of those areas. .

scholarly journals ROAD TEMPERATURE MODELLING WITHOUT IN-SITU SENSORS

2017 ◽  
Vol 12 (4) ◽  
pp. 241-247 ◽  
Author(s):  
Karol Opara ◽  
Jan Zieliński
Keyword(s):  
Energy Balance ◽  
Urban Areas ◽  
Initial Conditions ◽  
Forecast Error ◽  
Weather Data ◽  
Forecast Errors ◽  
The Road ◽  
In Situ Sensors ◽  
Pavement Temperature

Modelling of the pavement temperature facilitates winter road maintenance. It is used for predicting the glaze formation and for scheduling the spraying of the de-icing brine. The road weather is commonly forecasted by solving the energy balance equations. It requires setting the initial vertical profile of the pavement temperature, which is often obtained from the Road Weather Information Stations. The paper proposes the use of average air temperature from seven preceding days as a pseudo-observation of the subsurface temperature. Next, the road weather model is run with a few days offset. It first uses the recent, historical weather data and then the available forecasts. This approach exploits the fact that the energy balance models tend to “forget” their initial conditions and converge to the baseline solution. The experimental verification was conducted using the Model of the Environment and Temperature of Roads and the data from a road weather station in Warsaw over a period of two years. The additional forecast error introduced by the proposed pseudo-observational initialization averages 1.2 °C in the first prediction hour and then decreases in time. The paper also discusses the use of Digital Surface Models to take into account the shading effects, which are an essential source of forecast errors in urban areas. Limiting the use of in-situ sensors opens a perspective for an economical, largescale implementation of road meteorological models.

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