Adverse results of the economic crisis: A study on the emergence of enhanced formaldehyde (HCHO) levels seen from satellites over Greek urban sites

Zyrichidou, I.; Balis, Dimitris; Koukouli, M. E.; Δρόσογλου, Θεανώ; Bais, A. F.; Gratsea, Myrto; Gerasopoulos, E.; Liora, Natalia; Poupkou, A.; Giannaros, Christos; Melas, Dimitrios; Smedt, Isabelle De; Roozendaël, Michel Van; Boersma, K. F.; Valks, Pieter; Richter, Andreas

doi:10.1016/j.atmosres.2019.03.017

Cited by 19 publications

(9 citation statements)

References 58 publications

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“…The elevated AAOD levels in the period 2009-2011 are mainly due to the very high AAOD values in winter (~50% above the average level for 1998-2017). This is in agreement with the results of several recent studies reporting increased emissions of biomass burning and wood smoke aerosols [106,108,110], as well as high concentrations of other pollutants [111] in the particular period relative to the period before 2009. The increases in aerosol reported by all these studies are attributed to the increasing use of wood and pellets instead of oil and natural gas for domestic heating, after the beginning of the economic crisis in Greece [112].…”

Section: Long-term Variabilitysupporting

confidence: 93%

Deriving Aerosol Absorption Properties from Solar Ultraviolet Radiation Spectral Measurements at Thessaloniki, Greece

et al. 2019

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The gap in knowledge regarding the radiative effects of aerosols in the UV region of the solar spectrum is large, mainly due to the lack of systematic measurements of the aerosol single scattering albedo (SSA) and absorption optical depth (AAOD). In the present study, spectral UV measurements performed in Thessaloniki, Greece by a double monochromator Brewer spectrophotometer in the period 1998–2017 are used for the calculation of the aforementioned optical properties. The main uncertainty factors have been described and there is an effort to quantify the overall uncertainties in SSA and AAOD. Analysis of the results suggests that the absorption by aerosols is much stronger in the UV relative to the visible. SSA follows a clear annual pattern ranging from ~0.7 in winter to ~0.85 in summer at wavelengths 320–360 nm, while AAOD peaks in summer and winter. The average AAOD for 2009–2011 is ~50% above the 2003–2006 average, possibly due to increased emissions of absorbing aerosols related to the economic crisis and the metro-railway construction works in the city center.

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Section: Long-term Variabilitysupporting

confidence: 93%

Deriving Aerosol Absorption Properties from Solar Ultraviolet Radiation Spectral Measurements at Thessaloniki, Greece

et al. 2019

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“…Castellanos and Boersma, 2012, reported significant reductions in nitrogen oxides over Europe driven by environmental policy and the economic recession based on OMI/Aura observations between 2004 and 2010. Vrekoussis et al, 2013 andZyrichidou et al, 2019, report strong correlations between pollutant levels and economic indicators showing that the 2008 economic recession has resulted in proportionally lower levels of pollutants in large parts of Greece. The latter, for years 2008 to 2015, showed surprisingly that, while the wintertime tropospheric NO2 trends were negative, significant positive formaldehyde trends were observed from space, shown to be due to increased usage of affordable indoor heating methods (e.g.…”

Section: Sensing Abrupt Emission Changes From Space-borne Sensorsmentioning

confidence: 99%

Sudden changes in nitrogen dioxide emissions over Greece due to lockdown after the outbreak of COVID-19

Balis¹,

Koukouli²,

Skoulidou³

et al. 2020

Preprint

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Abstract. The unprecedented order, in modern peaceful times, for near-total lockdown of the Greek population, as means of protection against the Severe Acute Respiratory Syndrome CoronaVirus-2, commonly known as COVID-19, infection, has brought unintentional positive side-effects to the country's air quality levels. S5P/TROPOMI monthly mean tropospheric nitrogen dioxide (NO2) observations show an average decrease of −3 % to −26 % [−1 % to −27 %] with an average of −22 % [−11 %] for March and April 2020 respectively, compared to the previous year, over the six larger Greek metropolitan areas, attributable mostly to vehicular emission reductions. Furthermore, significant effects for shipping emissions over the Aegean Sea as well as the areas surrounding major Greek ports were observed, of approximately −12 % [−5 %]. For the capital city of Athens, weekly analysis was possible and it revealed a marked decline in NO2 load between −8 % and −43 % for seven of the eight weeks studied. Chemical transport modelling, provided by the LOTOS-EUROS CTM, shows that the magnitude of these reductions cannot solely be attributed to the difference in meteorological factors affecting NO2 levels during March and April 2020 and the equivalent time periods of the previous year. Taking this factor into account, the resulting decline was estimated to range between 0 % and −37 % for the five largest cities, with an average of ~ −10 %. As transport is the second largest sector that affects Greece's air quality, this occasion may well help policy makers in enforcing more targeted measures to aid Greece in further reducing emissions according to international air quality standards.

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“…They are used in many studies related to air quality and climate change (e.g. Stavrakou et al, 2014Stavrakou et al, , 2015Stavrakou et al, , 2016Stavrakou et al, , 2018Fortems-Cheiney et al, 2012;Marais et al, 2012;Mahajan et al, 2015;Choi and Souri, 2015;Zhu et al, 2016;Chan Miller et al, 2017;Jin et al, 2017;Barkley et al, 2017;Cao et al, 2018;Khan et al, 2018;Surl et al, 2018;Shen et al, 2019;Su et al, 2019;Zyrichidou et al, 2019;Jin et al, 2020;Souri et al, 2020;Wells et al, 2020;Franco et al, 2021;Opacka et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Comparative assessment of TROPOMI and OMI formaldehyde observations and validation against MAX-DOAS network column measurements

et al. 2021

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Abstract. The TROPOspheric Monitoring Instrument (TROPOMI), launched in October 2017 on board the Sentinel-5 Precursor (S5P) satellite, monitors the composition of the Earth's atmosphere at an unprecedented horizontal resolution as fine as 3.5 × 5.5 km2. This paper assesses the performances of the TROPOMI formaldehyde (HCHO) operational product compared to its predecessor, the OMI (Ozone Monitoring Instrument) HCHO QA4ECV product, at different spatial and temporal scales. The parallel development of the two algorithms favoured the consistency of the products, which facilitates the production of long-term combined time series. The main difference between the two satellite products is related to the use of different cloud algorithms, leading to a positive bias of OMI compared to TROPOMI of up to 30 % in tropical regions. We show that after switching off the explicit correction for cloud effects, the two datasets come into an excellent agreement. For medium to large HCHO vertical columns (larger than 5 × 1015 molec. cm−2) the median bias between OMI and TROPOMI HCHO columns is not larger than 10 % (< 0.4 × 1015 molec. cm−2). For lower columns, OMI observations present a remaining positive bias of about 20 % (< 0.8 × 1015 molec. cm−2) compared to TROPOMI in midlatitude regions. Here, we also use a global network of 18 MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments to validate both satellite sensors for a large range of HCHO columns. This work complements the study by Vigouroux et al. (2020), where a global FTIR (Fourier transform infrared) network is used to validate the TROPOMI HCHO operational product. Consistent with the FTIR validation study, we find that for elevated HCHO columns, TROPOMI data are systematically low (−25 % for HCHO columns larger than 8 × 1015 molec. cm−2), while no significant bias is found for medium-range column values. We further show that OMI and TROPOMI data present equivalent biases for large HCHO levels. However, TROPOMI significantly improves the precision of the HCHO observations at short temporal scales and for low HCHO columns. We show that compared to OMI, the precision of the TROPOMI HCHO columns is improved by 25 % for individual pixels and by up to a factor of 3 when considering daily averages in 20 km radius circles. The validation precision obtained with daily TROPOMI observations is comparable to the one obtained with monthly OMI observations. To illustrate the improved performances of TROPOMI in capturing weak HCHO signals, we present clear detection of HCHO column enhancements related to shipping emissions in the Indian Ocean. This is achieved by averaging data over a much shorter period (3 months) than required with previous sensors (5 years) and opens new perspectives to study shipping emissions of VOCs (volatile organic compounds) and related atmospheric chemical interactions.

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Adverse results of the economic crisis: A study on the emergence of enhanced formaldehyde (HCHO) levels seen from satellites over Greek urban sites

Cited by 19 publications

References 58 publications

Deriving Aerosol Absorption Properties from Solar Ultraviolet Radiation Spectral Measurements at Thessaloniki, Greece

Deriving Aerosol Absorption Properties from Solar Ultraviolet Radiation Spectral Measurements at Thessaloniki, Greece

Sudden changes in nitrogen dioxide emissions over Greece due to lockdown after the outbreak of COVID-19

Comparative assessment of TROPOMI and OMI formaldehyde observations and validation against MAX-DOAS network column measurements

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