Aircraft measurements of air pollution in the norwegian arctic

Physical properties, particle size distribution and chemical composition of the Arctic aerosol aloft have been studied to assess the origin of polluted layers of the Arctic air. Four measurement campaigns were made with the NILU aircraft during the period March 1983–JuIy 1984. Evidence of very long range transport of air masses to the Arctic is presented for summer and winter conditions. These polluted air masses are observed at higher altitudes (> 1.5 km). The layers of polluted air at lower altitudes are believed to be due to episodes of air mass transport from emission areas with a temperature similar to that in the Arctic in winter, and from local sources in summer. However, further aircraft measurements are needed to support these preliminary results.     

An assessment of the relationship between functional groups of weather elements and atmospheric pollution in Calgary,Canada

Nine regularly observed meteorological elements were classified into four functional groups—ventilation, energy, wet deposition and Chinook—and the contribution of each group to the air pollution process in Calgary, Canada, assessed by multiple correlation. While ventilation was the dominant process in most situations, the energy terms were the most significant during a smog. Heavy air pollution often occurred during a Chinook if the wind was weaker than 3 m s⁻¹. A linear combination of weather elements successfully separated clean from polluted air except on weekends and in very cold weather.     

A synoptic climatological approach to forecast concentrations of sulfur dioxide and nitrogen oxides in Hong Kong

The objective of this study is to develop an automated synoptic climatological procedure to forecast high air pollution concentrations in the most polluted synoptic categories. The procedure is able to identify air masses historically associated with high air pollution concentrations. The arrival of air mass can be predicted 24 or 48 h in advance with the use of the weather forecast data. The development and statistical basis of the procedure are discussed, and an analysis of the procedure's ability to forecast weather conditions associated with high air pollution concentrations is presented. In addition, the dataset of 24 weather variables from 1993 to 1995 is used to validate the procedure. The procedure predicts that 70.3 and 83.3% of total high and severe SO2 concentration days fall into the identified most polluted categories, and the corresponding figures for NOx are 47.8 and 73.7%. The agreement between observed and predicted values is generally good. The prediction models can explain about 58 and 45% of total variance for NOx and SO2 with RMSEs of 42.5 and 16.5 microg m(-3), respectively. They are smaller than 1 SD of the observations.     

Evaluation of weather conditions for methyl bromide ambient air monitoring in Monterey, Santa Cruz, and Kern Counties in the year 2000

Weather condition is one of the most important factors affecting spatial and temporal distributions of air pollutants, especially for short-term air dispersion. Abnormal weather conditions might lead to higher or lower ambient air concentrations than they would be under normal weather conditions. Therefore, testing for normality of weather conditions during the air monitoring period is an essential step for evaluating ambient air monitoring results. In this paper, a distance method was used to select a most representative weather station from the available candidates. An array of meteorological elements were identified that affect air dispersion and transportation. A statistical method was used to determine whether the weather conditions during the air monitoring period were significantly different from that of previous years. Using methyl bromide ambient air monitoring as a case study, this paper documents the methods, procedures, and results of weather analysis for Monterey, Santa Cruz, and Kern Counties during ambient air monitoring periods for methyl bromide in the year 2000. With a few exceptions, the meteorological elements and atmospheric stability factors, such as wind speeds, wind directions, and stability classes, during the monitoring period were in the normal range. Although there were higher frequencies of stable atmospheric conditions in Monterey/Santa Cruz Counties than in Kern County, weather conditions during the monitoring period were not significantly different from normal local weather conditions of previous years. Consequently, the subchronic air concentrations observed during the ambient air monitoring periods for methyl bromide in the year 2000 was taken under typical weather conditions of those areas at that time of the year.     

Applying hourly measurements of meteorological data and aerosol soluble ions in Taipei Basin, Taiwan

This study applies observational data composed of hourly weather and aerosol to discuss the aerosol characteristics within different weather systems. Based on cluster analysis, spring weather in Taipei Basin 2004 was characterised as five weather systems: humid/low south wind speed, dry cold/high east wind speed, humid cold/east wind, dry cold/northeaster, and northwestern convection wind. Under the humid/low south wind speed and northwestern convection wind systems, there are predominant influences of local vehicle/motor pollutant emissions and secondary pollution on the air quality. Asian dust storms were usually occurred under the weather of dry cold/high east wind speed. The regional air quality is more acceptable during the period of prevalent humid cold/east wind and dry cold/northeaster.     

Assessing the impact of weather events at mid-latitudes on the atmospheric transport of chemical pollutants using a 2-dimensional multimedia meteorological model

We investigate the long-range transport potential (LRTP) of five different classes of hypothetical chemical pollutants (volatile, multimedia, semivolatile, particle-associated and hydrophilic) during a low pressure weather event using a novel 2 (x- and z-axis)-Dimensional Multi-Media Meteorological Model (2D4M). The atmosphere (z-axis) is described by three atmospheric layers, where two layers constitute the boundary layer and the third layer the free troposphere. The 2D4M can describe distinct weather events on a regional scale and calculate the LRTP of chemicals as a function of time during these events. Four weather factors are used to model weather events and their influence on the atmospheric transport of chemicals: (1) temperature, (2) wind speed and mixing dynamics of the troposphere, (3) hydroxyl radical concentrations and (4) precipitation. We have modeled the impact of variability in each of these factors on LRTP of pollutants during a front event associated with a low pressure period that interrupts a dominant high pressure system. The physico-chemical properties of the pollutant determine which specific weather factors contribute most to variability in transport potential during the event. Volatile and multimedia chemicals are mainly affected by changing atmospheric mixing conditions, wind speeds and OH radical concentrations, while semivolatile substances are also affected by temperature. Low-vapor-pressure pollutants that are particle-associated, and water-soluble pollutants are most strongly affected by precipitation. Some chemical pollutants are efficiently transported from the boundary layer into the upper troposphere during the modeled low pressure event and are transported by much higher wind speeds than in the boundary layer. Our model experiments show that the transport potential of volatile, multimedia and semivolatile compounds is significantly increased during a front event as a result of efficient tropospheric mixing and fast wind speeds in the upper troposphere, whereas low-volatility and hydrophilic chemicals are largely scavenged from the atmosphere. In future LRTP assessment of chemical contaminants as required by the Stockholm Convention and the convention on long-range transboundary air pollution, it is therefore advised to prioritize volatile, multimedia and semivolatile chemicals that are identified in initial screening.     

Analysis of Air Quality Observations with the Aid of the Source-Receptor Relationship Approach

Abstract

In this study, an attempt was made to analyze time series of air quality measurements (O₃, SO₂, SO₄ ^2?NO_x) conducted at a remote place in the eastern Mediterranean (Finokalia at Crete Island in 1999) to obtain concrete information on potential contributions from emission sources. For the definition of a source-receptor relationship, advanced meteorological and dispersion models appropriate to identify “areas of influence” have been used. The model tools used are the Regional Atmospheric Modeling System and the Lagrangian-type particle dispersion model (forward and backward in time), with capabilities to derive influence functions and definition of “areas of influence.” When high levels of pollutants have been measured at the remote location of Finokalia, particles are released from this location (receptor) and traced backward in time. The influence function derived from particle distributions characterizes dispersion conditions in the atmosphere and also provides information on potential contributions from emission sources within the modeling domain to this high concentration. As was shown in the simulation results, the experimental site of Finokalia in Crete is influenced during the selected case studies, primarily by pollutants emitted from the urban conglomerate of Athens. Secondarily, it is influenced by polluted air masses arriving from Italy and/or the Black Sea Region. For some specific cases, air pollutants monitored at Finokalia were possibly related to war activities in the West Balkan Region (Kosovo).     

Analysis of air quality observations with the aid of the source-receptor relationship approach

In this study, an attempt was made to analyze time series of air quality measurements (O3, SO2, SO4(2-), NOx) conducted at a remote place in the eastern Mediterranean (Finokalia at Crete Island in 1999) to obtain concrete information on potential contributions from emission sources. For the definition of a source-receptor relationship, advanced meteorological and dispersion models appropriate to identify "areas of influence" have been used. The model tools used are the Regional Atmospheric Modeling System and the Lagrangian-type particle dispersion model (forward and backward in time), with capabilities to derive influence functions and definition of "areas of influence." When high levels of pollutants have been measured at the remote location of Finokalia, particles are released from this location (receptor) and traced backward in time. The influence function derived from particle distributions characterizes dispersion conditions in the atmosphere and also provides information on potential contributions from emission sources within the modeling domain to this high concentration. As was shown in the simulation results, the experimental site of Finokalia in Crete is influenced during the selected case studies, primarily by pollutants emitted from the urban conglomerate of Athens. Secondarily, it is influenced by polluted air masses arriving from Italy and/or the Black Sea Region. For some specific cases, air pollutants monitored at Finokalia were possibly related to war activities in the West Balkan Region (Kosovo).     

Occurrence and sources of particulate nitro-polycyclic aromatic hydrocarbons in ambient air in Denmark

The occurrence of selected nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) associated with atmospheric particulate matter has been investigated at an urban site and at a semi-rural site. For this purpose an analysis method based on gas chromatography and tandem ion trap mass spectrometry has been developed and applied. The nitro-PAH levels have been compared with levels of other air pollutants including unsubstituted PAHs, inorganic gases and particulate matter, as well as with meteorological parameters. Correlations and concentration ratios suggest that the dominant source of 9-nitroanthracene at the urban site is direct emissions, whereas at the semirural site its dominant source is atmospheric formation. The atmospheric formation of 2-nitrofluoranthene and 2-nitropyrene generally seems to be initiated by OH radicals during the day rather than by NO₃ radicals at night. The average contribution of the OH initiated formation is estimated to be in the range of 90–100%. However, under wintertime conditions with cloudy weather implying low OH radical production, NO₃ radicals may also be important as initiators of nitro-PAH formation. Samples influenced by transport of polluted air masses from the European continent have significantly elevated concentrations of atmospherically formed nitro-PAHs. The directly emitted nitro-PAHs, 1-nitropyrene and 3-nitrofluoranthene, do not exhibit elevated levels during such long-range transport episodes.     

Urban aerosol evolution and particle formation during wintertime temperature inversions

Aerosol temporal and spatial distributions during wintertime temperature inversions in Gothenburg, Sweden, have been characterized by ground-based and airborne particle measurements combined with lidar measurements. Ground inversions frequently developed during evenings and nights with stable cold conditions, and the low wintertime insolation often resulted in near neutral boundary layer conditions during day-time. Under these conditions ground level aerosol concentrations peaked during morning rush hours and often remained relatively high throughout the day due to inefficient ventilation. The particle number concentrations decreased slowly with increasing altitude within the boundary layer, and measurements slightly above the boundary layer suggested limited entrainment of polluted air into the free troposphere. High concentrations of ultrafine particles were observed throughout the boundary layer up to altitudes of 1100 m, which suggested that nucleation took place within the residual layer during the night and early morning. Recently formed particles were also observed around midday when the layer near ground was ventilated by mixing into the boundary layer, which indicated that ultrafine particles were either transported down from the residual layer to ground level or formed when the polluted surface layer mixed with the cleaner air above.     

Causes of the elevated nitrate aerosol levels during episodic days in Taichung urban area,Taiwan

The purpose of this study is to explore the possible reasons accounting for elevated nitrate aerosol levels during high particulate days (HPD) in Taichung urban area of central Taiwan. To achieve this goal, simultaneous measurements of particulate and gaseous pollutants were carried out from September 2004 to April 2005 using an annular denuder system (ADS). The formation rate of NO₂ to nitrate aerosol, calculated using the relevant chemical reactions, was employed to interpret enhanced nitrate aerosol concentrations during HPD. The observations showed that nitrate concentration during HPD was 14 times higher than that during low particulate days (LPD). The average formation rate during HPD was 4.0% h^?1, which was 3.1 times higher than that during LPD. The quantitative analysis showed that the formation rate was mainly influenced by temperature and relative humidity. Lower temperature and higher relative humidity led much nitrate aerosol formation in HPD. Moreover, the residence time analysis of air masses staying over the studied area showed that the slow-motion air retained high nitrate concentrations due to more nitrate aerosol converted from the precursors in NOx-rich areas.     

Air pollution characteristics associated with mesoscale atmospheric patterns in northwest continental Europe

An impact related daily air quality index (DAQx), calculated for 15 air quality monitoring stations (traffic, background, and industry) in Belgium, France, Germany and Luxembourg, was compared to mesoscale atmospheric patterns between 2001 and 2007. Meteorological conditions were described by the Hess and Brezowsky synoptic weather classification system and gridded data of the EU FP6 ENSEMBLES project of total precipitation and mean surface temperature. DAQx values indicate sufficient to poor air quality in the urban area of Brussels and at urban traffic stations, as well as satisfactory air quality at the background stations. The air quality index refers to more than 90% to the presence of high PM₁₀, O₃ and NO₂ concentrations. SO₂ and CO play only a minor role. The investigation of weather regimes indicates that zonal and mixed cyclonic circulation regimes are associated with better air quality than meridional and anticyclonic weather regimes. In general, weather regimes with high daily precipitation lead to better air quality than dryer air masses because of lower contribution of PM₁₀ to the air quality index. A trend analysis of weather regimes from 1978 to 2007 shows significant (α = 0.05) positive trends for weather classes associated with lower PM₁₀ concentrations. The results of a case study at a German station examining the relationship between PM₁₀ concentrations and local meteorological quantities (wind speed and precipitation) confirm the results of the regional analysis.     

Continuous measurement of gaseous pollutants in Buenos Aires city

Data on CO, NO, NO₂ and O₃ concentrations measured in Buenos Aires city using a continuous monitoring station are reported. This is the first systematic study of this kind carried out in the city, which is, together with its surroundings, the third more populated in Latin America. Measurements were performed during 12 months in one of the principal avenues near downtown. Results indicate that vehicular traffic is the principal source of CO and NO_x. The concentration of O₃ is generally quite low and results from the mixing of clean air masses with exhaust gases containing high amounts of NO. The monthly averages of CO and NO decrease from Winter to Summer in correlation with the increase of the mean wind speed and average temperature. These results are compared with previous measurements on the spatial distribution of NO₂ in the whole city using passive diffusion tubes and with the concentration of CO, which is being continuously registered since several years in the downtown area. Measurements performed at a green, windy, low traffic area beneath the La Plata river are also shown.     

Formation and Transport of the Madrid Ozone Plume

Abstract

The main results of an experimental study focusing on the formation and transport of photochemical pollution in the Madrid air basin are presented. This southern European, heavily populated urban area is located on an elevated plateau at a height of 700 m, near a mountain range with maximum heights of around 2,400 m. Daily and seasonal cycles of ozone were documented during a one-year survey at three semi-rural sites located 30 km away from the urban center. Maximum hourly values of up to 140 ppb were measured, and the ozone generated within the urban plume on polluted days (when values exceeded 90 ppb) has been estimated at around 40-50 ppb.A meteorological characterization of these smoggy days pointed out the influence of thermally induced local wind flows on the concentration daily cycles at the measuring sites, denoting a preferred advection of the urban plume. Moreover, during intensive summer field campaigns, the use of meteorological and ozone sondes, as well as an instrumented aircraft, revealed some features about the horizontal and vertical distribution of the polluted air masses, as well as their evolution within the planetary boundary layer. Ozone plumes have been detected up to 100 km away from the city, usually mixed in a layer that reaches a height of 1,000-1,500 m in the afternoon. On some occasions, ozone-enriched layers have been detected as high as 4,000 m during morning hours, suggesting possible tropospheric injection induced by topographydriven flows or convective mesoscale systems that are usually present in the center of the Iberian Peninsula in the summer.     

Origin of polluted air masses in the Alps. An overview and first results for MONARPOP

The contribution of ZAMG to MONAROP consists of special weather forecasts to control the SOCs sampling procedure and of the analysis of the specific transport processes for SOCs, which is still in progress.In this paper, air pollutant transport into the Alps is demonstrated by examples of inorganic pollutants: Measurements of NO_x and ozone provide evidence for air pollutant transport by local wind systems (valley and slope winds), especially at low elevated sites of the Alps. In addition, trajectory analyses for the high elevation sites demonstrate the importance of large scale synoptic air pollutant transport. The effects of these transport processes with different spatial and temporal scales are governed by the physical and chemical properties of the particular pollutant.First results for the high alpine MONARPOP stations show that air masses from east Europe influence mostly Sonnblick (Austria), whereas the influence of the Po basin is strongest at Weissfluhjoch (Switzerland).     

Large-Scale Weather Influences on Community Air Pollution Potential in the United States

This paper describes the large-scale weather features that typically are associated with relatively rapid and slow atmospheric dispersion. Specific examples for some well-known air pollution incidents are illustrated and discussed. Particular attention is paid to the features of quasi-stagnating anticyclones, the typical weather system associated with persistent and extensive areas of sluggish dispersion. On the large scale, the basic quantitative parameters of dispersion over urban areas are the mixing height and the wind speed averaged through that height. These parameters are defined and discussed. Mean morning and afternoon mixing heights and wind speeds are presented for four locations across the United States, illustrating their diurnal, seasonal, and spatial variations. Also for these four locations, data are given on the climatological occurrence of periods during which critical values of the basic parameters were not exceeded. The spatial distributions of mixing heights and average wind speeds during a well-documented air pollution episode are presented.     

Coral reef aerosol emissions in response to irradiance stress in the Great Barrier Reef,Australia

We investigate the correlation between stress-related compounds produced by corals of the Great Barrier Reef (GBR) and local atmospheric properties—an issue that goes to the core of the coral ecosystem’s ability to survive climate change. We relate the variability in a satellite decadal time series of fine-mode aerosol optical depth (AOD) to a coral stress metric, formulated as a function of irradiance, water clarity, and tide, at Heron Island in the southern GBR. We found that AOD was correlated with the coral stress metric, and the correlation increased at low wind speeds, when horizontal advection of air masses was low and the production of non-biogenic aerosols was minimal. We posit that coral reefs may be able to protect themselves from irradiance stress during calm weather by affecting the optical properties of the atmosphere and local incident solar radiation.     

Patterns and concentrations of PM10 in a mountainous basin region

In this study, continuous data of PM10 (particles with aerodynamic diameter < 10 microns) concentration measurements for a 4-yr period were analyzed. These measurements have been carried out in the Eordea Basin, an industrial area in the northwestern mountainous region of Greece. The annual, monthly, and diurnal patterns are presented and investigated regarding the prevailing meteorological conditions and atmospheric processes that affect the ambient concentrations of PM10. The effect of wind on controlling PM10 concentration is also discussed. Based on the data analysis, an attempt is made to provide useful information about air quality levels, taking into account U.S. Environmental Protection Agency air quality standards.     

Energy Consumption Reduction Using Two-Stage Venturi Scrubbers

Performance of a three-component monostatic Doppler sodar was compared with performance of collocated meteorological tower instruments and evaluated for electric utility applications. The sensors were components of an air pollution monitoring network that was upgraded to assess the impact of coal conversion on ambient air quality at Northeast Utilities' Mt. Tom Generating Station situated in rugged terrain in the Connecticut River valley of western Massachusetts. To determine how well sodar and tower measurements agree, and how reliable sodar is for this type of application, meteorological data and system performance statistics obtained from August 1982 through July 1983 were examined. A statistical comparison of wind speed and direction measurements at 50 m indicated good agreement between the two monitoring techniques. High correlations also were observed for data collected during various weather conditions. System reliability was demonstrated by data recovery rates and sodar vertical range capabilities. Monthly data recovery rates exceeded 90 percent and occasionally approached 98 percent after initial break-in problems were resolved. Sodar range was 100 m more than 95 percent of the time and 200 m more than 50 percent of the time. Under optimum conditions, the vertical range extended beyond 200 m.