scholarly journals CO2 variability in the Mexico City region from in situ measurements at an urban and a background site

2020 ◽  
Author(s):  
Eugenia González del Castillo ◽  
Noémie Taquet ◽  
Alejandro Bezanilla ◽  
Wolfgang Stremme ◽  
Michel Ramonet ◽  
...  
Keyword(s):  
Mexico City ◽  
Growth Rates ◽  
Urban Areas ◽  
Layer Growth ◽  
Dry Season ◽  
University Campus ◽  
City Region ◽  
Air Masses ◽  
Long Term Trends

Urban areas are important contributors to the increase of global CO2levels due to human activities, but continuous records of CO2concentration in cities are scarce, especially in the developing world. In this study we present five years of simultaneous, in-situmeasurements at a university campus in the south of Mexico City (UNAM) and at a high-altitude station, the Altzomoni atmospheric observatory (ALTZ), 60 km apart from the first site. The characteristics of the daily cycles, seasonality, and long-term trends were extracted from both time series. The features of the daily and seasonal cycles at UNAM are dominated by the dynamics of the boundary layer growth, while the seasonality at Altzomoni is determined by both the local meteorology and the photosynthetic activity of the vegetation. Annual CO2 growth rates of 2.4 and 2.6 ppm yr-1 were estimated for UNAM and Altzomoni, respectively, in close agreement with reported global growth rates and with previous estimates of total column CO2trends. The simultaneous monitoring at the urban and the mountain sites revealed a regular exchange of air masses between the city and its vicinities. The annual cycle at UNAM shows a secondary CO2maximum at the end of the dry season likely due to incoming air parcels enriched with emissions from agricultural burnings. Likewise, the daily CO2cycle at ALTZ during the dry season shows evidence of a daily afternoon arrival of polluted air masses from the neighboring urban areas. This study lays the foundation of an upcoming expansion in the CO2measurement sites and capabilities in the metropolitan area of Mexico City.

Long-Term Trends in Motor Vehicle Emissions in U.S. Urban Areas

2013 ◽  
Vol 47 (17) ◽  
pp. 10022-10031 ◽  
Author(s):  
Brian C. McDonald ◽  
Drew R. Gentner ◽  
Allen H. Goldstein ◽  
Robert A. Harley
Keyword(s):  
Urban Areas ◽  
Vehicle Emissions ◽  
Motor Vehicle ◽  
Motor Vehicle Emissions ◽  
Long Term Trends

scholarly journals Aerosol airmass type mapping over the urban Mexico City region from space-based multi-angle imaging

2013 ◽  
Vol 13 (3) ◽  
pp. 7931-7978 ◽  
Author(s):  
F. Patadia ◽  
R. A. Kahn ◽  
J. A. Limbacher ◽  
S. P. Burton ◽  
R. A. Ferrare ◽  
...  
Keyword(s):  
Mexico City ◽  
Urban Pollution ◽  
Single Scattering ◽  
High Spectral Resolution ◽  
Urban Region ◽  
Retrieval Algorithm ◽  
City Region ◽  
Air Mass ◽  
Air Masses ◽  
Type Mapping

Abstract. Using Multi-angle Imaging SpectroRadiometer (MISR) and sub-orbital measurements from the 2006 INTEX-B/MILAGRO field campaign, in this study we demonstrate MISR's ability to map different aerosol air mass types over the Mexico City metropolitan area. The aerosol air mass distinctions are based on shape, size and single scattering albedo retrievals from the MISR Research Aerosol Retrieval algorithm. In this region, the research algorithm identifies dust-dominated aerosol mixtures based on non-spherical particle shape, whereas spherical biomass burning and urban pollution particles are distinguished by particle size. Four distinct aerosol air masses are identified in the MISR data on 6 March 2006; these results are supported by coincident, airborne high-spectral-resolution lidar (HSRL) measurements. Aerosol optical depth (AOD) gradients are also consistent between the MISR and sub-orbital measurements, but particles having SSA558≈0.7 must be included in the retrieval algorithm to produce good absolute AOD comparisons over pollution-dominated aerosol air masses. The MISR standard V22 AOD product, at 17.6 km resolution, captures the observed AOD gradients qualitatively, but retrievals at this coarse spatial scale and with limited spherical absorbing particle options underestimate AOD and do not retrieve particle properties adequately over this complex urban region. However, we demonstrate how AOD and aerosol type mapping can be accomplished with MISR data over urban regions, provided the retrieval is performed at sufficiently high spatial resolution, and with a rich enough set of aerosol components and mixtures.

scholarly journals Internal consistency of the IAGOS ozone and carbon monoxide measurements for the last 25 years

2020 ◽  
Author(s):  
Romain Blot ◽  
Philippe Nedelec ◽  
Damien Boulanger ◽  
Pawel Wolff ◽  
Bastien Sauvage ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Data Base ◽  
Internal Consistency ◽  
Selection Criteria ◽  
Meteorological Data ◽  
Atmospheric Composition ◽  
European Research ◽  
Air Masses ◽  
Long Term Trends

Abstract. The In-service Aircraft for a Global Observing System is a European research infrastructure that equips Airbus A340/330 with a system for monitoring atmospheric composition. The IAGOS instruments have three different configurations: IAGOS-CORE, IAGOS-MOZAIC and IAGOS-CARIBIC. Since 1994, there have been a total of 17 aircraft equipped. In this study, we perform an inter-comparison of about 8000 landing and take-off profiles to compare the O3 and CO measurements performed from these different configurations. The collocated profiles used in the study met various selection criteria. The first was a maximal 1 hour time difference between an ascent or descent by two different aircraft at the same airport and the second was a selection based on the similarity of air masses based on the meteorological data acquired by the aircraft. We provide here an evaluation of the internal consistency of the O3 and CO measurements since 1994. For both O3 and CO, we find no drift in the bias amongst the different instrument units (6 O3 and 6 CO IAGOS-MOZAIC instruments, 9 IAGOS-CORE Package 1 and the 2 instruments used in the IAGOS-CARIBIC aircraft). This results gives us confidence that the entire IAGOS data base can be treated as one continuous program, and is therefore appropriate for studies of long-term trends.

scholarly journals Local government in England: evolution and long-term trends

2020 ◽  
Author(s):  
John Parr
Keyword(s):  
Structural Change ◽  
Local Government ◽  
Urban Areas ◽  
Path Dependence ◽  
Regional Government ◽  
Early Nineteenth Century ◽  
The United Kingdom ◽  
History Of ◽  
Long Term Trends

This paper traces the history of local government in England (as opposed to the United Kingdom) since the early nineteenth century, and explores five long-term trends in its evolution. These are path dependence; the occurrence of major structural change; the phenomenon of policy reversal; the treatment of urban areas; and resistance to regional government. The author concludes that throughout the period under study, policy towards local government has exhibited a ‘pendulum effect’, with two opposing emphases operating in a sequential, rather than a simultaneous manner.

scholarly journals Long-term trends of surface ozone and its influencing factors at the Mt. Waliguan GAW station, China, Part 2: Variation mechanism and links to some climate indices

2017 ◽  
Author(s):  
Wanyun Xu ◽  
Xiaobin Xu ◽  
Meiyun Lin ◽  
Weili Lin ◽  
Jie Tang ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Trajectory Analysis ◽  
Surface Ozone ◽  
Eastern China ◽  
Sunspot Cycle ◽  
Anthropogenic Emissions ◽  
Climate Indices ◽  
Air Masses ◽  
Long Term Trends

Abstract. Interannual variability and long-term trends of tropospheric ozone are both of environmental and climate concerns. Ozone measured at Mt. Waliguan Observatory (WLG, 3816 m asl) on the Tibetan Plateau over the period 19947ndash;2013 has increased significantly by 0.2–0.3 ppbv year-1 during spring and autumn, but shows a much smaller trend in winter and no significant trend in summer. Here we explore the factors driving the observed ozone changes at WLG using backward trajectory analysis, chemistry-climate model hindcast simulations (GFDL-AM3), a trajectory-mapped ozonesonde dataset and various climate indices. A stratospheric ozone tracer implemented in GFDL-AM3 indicates that stratosphere-to-troposphere transport (STT) can explain ~ 70 % of the observed springtime ozone increase at WLG, consistent with an increase in the NW air mass frequency inferred from the trajectory analysis. Enhanced STT associated with the strengthening of the mid-latitude jet stream contributes to the observed high-ozone anomalies at WLG during the springs of 1999 and 2012. During autumn, observations at WLG are more heavily influenced by polluted air masses originated from Southeast Asia than in the other seasons. Rising Asian anthropogenic emissions of ozone precursors is the key driver of increasing autumnal ozone observed at WLG, as supported by the GFDL-AM3 model with time-varying emissions, which captures the observed ozone increase (0.26 ± 0.11 ppbv year-1). AM3 simulates a greater ozone increase of 0.38 ± 0.11 ppbv year-1 at WLG in autumn under conditions with strong transport from Southeast Asia and shows no significant ozone trend in autumn when anthropogenic emissions are held constant in time. During summer, WLG is mostly influenced by easterly air masses but these trajectories do not extend to the polluted regions of eastern China and have decreased significantly over the last two decades, which likely explains why summertime ozone measured at WLG shows no significant trend despite ozone increases in Eastern China. Analysis of the Trajectory-mapped Ozonesonde dataset for the Stratosphere and Troposphere (TOST) and trajectory residence time reveals increases in direct ozone transport from the eastern sector during autumn, which adds to the autumnal ozone increase. We further examine the links of ozone variability at WLG to the QBO, the North Atlantic Oscillation (NAO), the East Asian summer monsoon (EASM) and the sunspot cycle. Our results suggest that the 2–3 year, 3–7 year and 11 year periodicities are linked to QBO, EASMI and NAO and the sunspot cycle, respectively. A multivariate regression analysis is performed to quantify the relative contributions of various factors to surface ozone concentrations at WLG. Through an observational and modelling analysis, this study demonstrates the complex relationships between surface ozone at remote locations and its dynamical and chemical influencing factors.

scholarly journals Secondary new particle formation in Northern Finland Pallas site between the years 2000 and 2010

2011 ◽  
Vol 11 (24) ◽  
pp. 12959-12972 ◽  
Author(s):  
E. Asmi ◽  
N. Kivekäs ◽  
V.-M. Kerminen ◽  
M. Komppula ◽  
A.-P. Hyvärinen ◽  
...  
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Detailed Examination ◽  
Particle Formation ◽  
New Particle Formation ◽  
Air Masses ◽  
Event Frequency ◽  
Marine Air

Abstract. Secondary new particle formation affects atmospheric aerosol and cloud droplet numbers and thereby, the aerosol effects on climate. In this paper, the frequency of nucleation events and the associated particle formation and growth rates, along with their seasonal variation, was analysed based on over ten years of aerosol measurements conducted at the Pallas GAW station in northern Finland. The long-term measurements also allowed a detailed examination of factors possibly favouring or suppressing particle formation. Effects of meteorological parameters and air mass properties as well as vapour sources and sinks for particle formation frequency and event parameters were inspected. In addition, the potential of secondary particle formation to increase the concentration of cloud condensation nuclei (CCN) sized particles was examined. Findings from these long-term measurements confirmed previous observations: event frequency peaked in spring and the highest growth rates were observed in summer, affiliated with increased biogenic activity. Events were almost exclusively observed in marine air masses on sunny cloud-free days. A low vapour sink by the background particle population as well as an elevated sulphuric acid concentration were found to favour particle formation. These were also conditions taking place most likely in marine air masses. Inter-annual trend showed a minimum in event frequency in 2003, when also the smallest annual median of growth rate was observed. This gives further evidence of the importance and sensitivity of particle formation for the condensing vapour concentrations at Pallas site. The particle formation was observed to increase CCN80 (>80 nm particle number) concentrations especially in summer and autumn seasons when the growth rates were the highest. When the growing mode exceeded the selected 80 nm limit, on average in those cases, 211 ± 114% increase of CCN80 concentrations was observed.

Long-Term Trends of Carbon Monoxide Total Columnar Amount in Urban Areas and Background Regions: Ground- and Satellite-based Spectroscopic Measurements

2018 ◽  
Vol 35 (7) ◽  
pp. 785-795 ◽  
Author(s):  
Pucai Wang ◽  
N. F. Elansky ◽  
Yu. M. Timofeev ◽  
Gengchen Wang ◽  
G. S. Golitsyn ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Urban Areas ◽  
Spectroscopic Measurements ◽  
Long Term Trends

scholarly journals Internal consistency of the IAGOS ozone and carbon monoxide measurements for the last 25 years

2021 ◽  
Vol 14 (5) ◽  
pp. 3935-3951
Author(s):  
Romain Blot ◽  
Philippe Nedelec ◽  
Damien Boulanger ◽  
Pawel Wolff ◽  
Bastien Sauvage ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Internal Consistency ◽  
Selection Criteria ◽  
Meteorological Data ◽  
Atmospheric Composition ◽  
European Research ◽  
Air Masses ◽  
Civil Aircraft ◽  
Long Term Trends

Abstract. The In-service Aircraft for a Global Observing System (IAGOS) is a European research infrastructure that equips the Airbus A340/330 with a system for monitoring atmospheric composition. The IAGOS instruments have three different configurations: IAGOS-Core, IAGOS – Measurement of Ozone and Water Vapor by Airbus In Service Aircraft (IAGOS-MOZAIC) and IAGOS – Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container (IAGOS-CARIBIC). Since 1994, there have been a total of 17 aircraft equipped. In this study, we perform an intercomparison of about 8000 landing and takeoff profiles to compare the O3 and CO measurements performed from these different configurations. The collocated profiles used in the study met various selection criteria. The first was a maximal 1 h time difference between an ascent or descent by two different aircraft at the same airport and the second was a selection based on the similarity of air masses based on the meteorological data acquired by the aircraft. We provide here an evaluation of the internal consistency of the O3 and CO measurements since 1994. For both O3 and CO, we find no drift in the bias amongst the different instrument units (six O3 and six CO IAGOS-MOZAIC instruments, nine IAGOS-Core Package1 and the two instruments used in the IAGOS-CARIBIC aircraft). This result gives us confidence that the entire IAGOS database can be treated as one continuous program and is therefore appropriate for studies of long-term trends.

scholarly journals Long-term trends of surface ozone and its influencing factors at the Mt Waliguan GAW station, China – Part 2: The roles of anthropogenic emissions and climate variability

2018 ◽  
Vol 18 (2) ◽  
pp. 773-798 ◽  
Author(s):  
Wanyun Xu ◽  
Xiaobin Xu ◽  
Meiyun Lin ◽  
Weili Lin ◽  
David Tarasick ◽  
...  
Keyword(s):  
Trajectory Analysis ◽  
Surface Ozone ◽  
Eastern China ◽  
Sunspot Cycle ◽  
Anthropogenic Emissions ◽  
South East Asia ◽  
Data Set ◽  
Air Masses ◽  
Long Term Trends

Abstract. Inter-annual variability and long-term trends in tropospheric ozone are both environmental and climate concerns. Ozone measured at Mt Waliguan Observatory (WLG, 3816 m a.s.l.) on the Tibetan Plateau over the period of 1994–2013 has increased significantly by 0.2–0.3 ppbv yr−1 during spring and autumn but shows a much smaller trend in winter and no significant trend in summer. Here we explore the factors driving the observed ozone changes at WLG using backward trajectory analysis, chemistry–climate model hindcast simulations (GFDL AM3), a trajectory-mapped ozonesonde data set, and several climate indices. A stratospheric ozone tracer implemented in GFDL AM3 indicates that stratosphere-to-troposphere transport (STT) can explain ∼ 60 % of the simulated springtime ozone increase at WLG, consistent with an increase in the NW air-mass frequency inferred from the trajectory analysis. Enhanced STT associated with the strengthening of the mid-latitude jet stream contributes to the observed high ozone anomalies at WLG during the springs of 1999 and 2012. During autumn, observations at WLG are more heavily influenced by polluted air masses originating from South East Asia than in the other seasons. Rising Asian anthropogenic emissions of ozone precursors are the key driver of increasing autumnal ozone observed at WLG, as supported by the GFDL AM3 model with time-varying emissions, which captures the observed ozone increase (0.26 ± 0.11 ppbv yr−1). AM3 simulates a greater ozone increase of 0.38 ± 0.11 ppbv yr−1 at WLG in autumn under conditions with strong transport from South East Asia and shows no significant ozone trend in autumn when anthropogenic emissions are held constant in time. During summer, WLG is mostly influenced by easterly air masses, but these trajectories do not extend to the polluted regions of eastern China and have decreased significantly over the last 2 decades, which likely explains why summertime ozone measured at WLG shows no significant trend despite ozone increases in eastern China. Analysis of the Trajectory-mapped Ozonesonde data set for the Stratosphere and Troposphere (TOST) and trajectory residence time reveals increases in direct ozone transport from the eastern sector during autumn, which adds to the autumnal ozone increase. We further examine the links of ozone variability at WLG to the quasi-biennial oscillation (QBO), the East Asian summer monsoon (EASM), and the sunspot cycle. Our results suggest that the 2–3-, 3–7-, and 11-year periodicities are linked to the QBO, EASM index, and sunspot cycle, respectively. A multivariate regression analysis is performed to quantify the relative contributions of various factors to surface ozone concentrations at WLG. Through an observational and modelling analysis, this study demonstrates the complex relationships between surface ozone at remote locations and its dynamical and chemical influencing factors.

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