Satellite Observations of NO<sub>2</sub> Trend over Romania

Constantin, Daniel-Eduard; Voiculescu, Mirela; Georgescu, L.

doi:10.1155/2013/261634

Cited by 16 publications

(16 citation statements)

References 23 publications

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“…This feature is most likely related to the worldwide financial crisis, which started in 2008 and had a substantial im-pact on the global economy during this period. This result provides a global perspective to supplement previous studies that looked in detail at tropospheric NO 2 columns as a proxy for the economic downturn over a single megacity (Vrekoussis et al, 2013) or provided regional studies about the same topic (Russell et al, 2012;Castellanos and Boersma, 2012;De Ruyter de Wildt et al, 2012). Figure 5c also indicates an increase in tropospheric NO 2 levels from late 2003 through early 2004.…”

Section: Absolutesupporting

confidence: 56%

Recent satellite-based trends of tropospheric nitrogen dioxide over large urban agglomerations worldwide

Schneider¹,

Lahoz²,

A³

2014

Preprint

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Abstract. Trends in tropospheric nitrogen dioxide (NO2) concentrations over 66 large urban agglomerations worldwide have been computed using data from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument onboard the Envisat platform for the period August 2002 to March 2012. A seasonal model including a linear trend was fitted to the satellite-based time series over each site. The results indicate distinct spatial patterns in trends. While agglomerations in Europe, North America, and some locations in East Asia/Oceania show decreasing tropospheric NO2 levels on the order of −5 % yr−1, rapidly increasing levels of tropospheric NO2 are found for agglomerations in large parts of Asia, Africa, and South America. The site with the most rapidly increasing absolute levels of tropospheric NO2 was found to be Tianjin in China with a trend value of 3.04 (±0.47) × 1015 molecules cm−2 yr−1, whereas the site with the most rapidly increasing relative trend was Kabul in Afghanistan with 14.3 (±2.2) % yr−1. In total, 34 sites exhibited increasing trends of tropospheric NO2 throughout the study period, 24 of which were found to be statistically significant. A total of 32 sites showed decreasing levels of tropospheric NO2 during the study period, of which 20 sites did so at statistically significant magnitudes. Overall, going beyond the relatively small set of megacities investigated previously, this study provides the first consistent analysis of recent changes in tropospheric NO2 levels over most large urban agglomerations worldwide.

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Section: Absolutesupporting

confidence: 56%

Recent satellite-based trends of tropospheric nitrogen dioxide over large urban agglomerations worldwide

Schneider¹,

Lahoz²,

A³

2014

Preprint

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“…OMI is a remote sensing space instrument onboard the Aura satellite that provides a raw NO 2 product called DSCD (Differential Slant Column Density), which is retrieved using Differential Optical Absorption Spectroscopy (DOAS) in the 405–465 nm range. Satellite measurements provide valuable data about atmospheric pollutants, including NO 2 [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ] at a large scale. The most refined product of OMI is the tropospheric Vertical Column Density (VCD), which is the result of a near real-time retrieval algorithm that gives a 0.7 × 10 15 molec./cm 2 uncertainty for each individual pixel [ 26 ].…”

Section: Data and Methods/experimentalmentioning

confidence: 99%

Role of Meteorological Parameters in the Diurnal and Seasonal Variation of NO2 in a Romanian Urban Environment

Voiculescu

Constantin

Condurache-Bota

et al. 2020

IJERPH

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The main purpose of this study was to investigate whether meteorological parameters (temperature, relative humidity, direct radiation) play an important role in modifying the NO2 concentration in an urban environment. The diurnal and seasonal variation recorded at a NO2 traffic station was analyzed, based on data collected in situ in a Romanian city, Braila (45.26° N, 27.95° E), during 2009–2014. The NO2 atmospheric content close to the ground had, in general, a summer minimum and a late autumn/winter maximum for most years. Two diurnal peaks were observed, regardless of the season, which were more evident during cold months. Traffic is an important contributor to the NO2 atmospheric pollution during daytime hours. The variability of in situ measurements of NO2 concentration compared relatively well with space-based observations of the NO2 vertical column by the Ozone Monitoring Instrument (OMI) satellite for most of the period under scrutiny. Data for daytime and nighttime (when the traffic is reduced) were analyzed separately, in the attempt to isolate meteorological effects. Meteorological parameters are not fully independent and we used partial correlation analysis to check whether the relationships with one parameter may be induced by another. The correlation between NO2 and temperature was not coherent. Relative humidity and solar radiation seemed to play a role in shaping the NO2 concentration, regardless of the time of day, and these relationships were only partially interconnected.

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“…The city of Galati is located in South-East of Romania, has a population of~250,000 inhabitants and a surface of~250 km 2 . The major pollution sources are a steel factory and an oil factory (whose locations are shown in Figure 3) and road traffic [37][38][39]. Galati can be rated as a medium polluted city, where the maximum tropospheric NO 2 vertical column density (VCD) content measured, e.g., by a mobile DOAS system, is 1.5 × 10 16 molec./cm 2 .…”

Section: Observation Sitementioning

confidence: 99%

Observations of Atmospheric NO2 Using a New Low-Cost MAX-DOAS System

et al. 2020

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This article describes the prototype of a new MAX-DOAS (multi-axis differential optical absorption spectroscopy) system built at “Dunarea de Jos” University of Galati (UGAL), Romania, and the first results of its use to observe NO2 content over Galati city (45.42° N, 28.04° E). The new equipment is a ground-based MAX-DOAS system capable of measuring the spatial distribution of DSCD (differential slant column densities) of several trace gases using horizontal and vertical observations. The new optic system, named UGAL-2-DOAS, is an in-house, low-cost, solution in comparison to the existing market of the MAX-DOAS systems. This paper describes the technical design and capabilities of the new MAX-DOAS instrument. The UGAL-2D-DOAS system was tested in April and June 2017 in Galati city. Measurements over three days were selected for the present manuscript. Full azimuthal (0–360°), local celestial meridian observations and other elevation angle sequence measurements (e.g., E–W) were performed. We found that the new MAX-DOAS system is able to detect diurnal variation and the local source emissions of NO2 from the urban environment. Also, we present concomitant zenith-sky car-DOAS observations measurements around the location of the new MAX-DOAS instrument. Comparing the horizontal scanning sequence of the new developed instrument with the mobile DOAS observations, we found that both systems can indicate and detect the same NO2 sources.

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Satellite Observations of NO₂ Trend over Romania

Cited by 16 publications

References 23 publications

Recent satellite-based trends of tropospheric nitrogen dioxide over large urban agglomerations worldwide

Recent satellite-based trends of tropospheric nitrogen dioxide over large urban agglomerations worldwide

Role of Meteorological Parameters in the Diurnal and Seasonal Variation of NO2 in a Romanian Urban Environment

Observations of Atmospheric NO2 Using a New Low-Cost MAX-DOAS System

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Satellite Observations of NO2 Trend over Romania

Cited by 16 publications

References 23 publications

Recent satellite-based trends of tropospheric nitrogen dioxide over large urban agglomerations worldwide

Recent satellite-based trends of tropospheric nitrogen dioxide over large urban agglomerations worldwide

Role of Meteorological Parameters in the Diurnal and Seasonal Variation of NO2 in a Romanian Urban Environment

Observations of Atmospheric NO2 Using a New Low-Cost MAX-DOAS System

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Satellite Observations of NO₂ Trend over Romania