scholarly journals Black carbon aerosol reductions during COVID-19 confinement quantified by aircraft measurements over Europe

2022 ◽  
Author(s):  
Ovid Oktavian Krüger ◽  
Bruna A. Holanda ◽  
Sourangsu Chowdhury ◽  
Andrea Pozzer ◽  
David Walter ◽  
...  
Keyword(s):  
Black Carbon ◽  
Human Activities ◽  
Transport Model ◽  
Air Pollutant ◽  
Climate Forcing ◽  
Atmospheric Conditions ◽  
Chemistry Transport Model ◽  
Black Carbon Aerosol ◽  
Positive Effect

Abstract. The abrupt reduction in human activities during the first lockdown of the COVID-19 pandemic created unprecedented atmospheric conditions. To quantify the changes in lower tropospheric air pollution, we conducted the BLUESKY aircraft campaign and measured vertical profiles of black carbon (BC) aerosol particles over Western and Southern Europe in May and June 2020. We compared the results to similar measurements of the EMeRGe EU campaign performed in July 2017 and found that the BC mass concentrations (MBC) were reduced by about 47 %. For BC particle number concentrations, we found comparable reductions. Based on EMAC chemistry-transport model simulations, we find differences in meteorological conditions and flight patterns responsible for about 7 % of the reductions in MBC, whereas 40 % can be attributed to reduced anthropogenic emissions. Our results reflect the strong and immediate positive effect of changes in human activities on air quality and the atmospheric role of BC aerosols as a major air pollutant and climate forcing agent in the Anthropocene.

scholarly journals Simulating age of air and the distribution of SF<sub>6</sub> in the stratosphere with the SILAM model

2020 ◽  
Vol 20 (9) ◽  
pp. 5837-5859
Author(s):  
Rostislav Kouznetsov ◽  
Mikhail Sofiev ◽  
Julius Vira ◽  
Gabriele Stiller
Keyword(s):  
Transport Model ◽  
Michelson Interferometer ◽  
Direct Calculation ◽  
Chemistry Transport Model ◽  
Simultaneous Application ◽  
Separation Of Gases ◽  
Stratospheric Circulation ◽  
Tracer Accumulation ◽  
Accumulation Method

Abstract. The paper presents a comparative study of age of air (AoA) derived from several approaches: a widely used passive-tracer accumulation method, the SF6 accumulation, and a direct calculation of an ideal-age tracer. The simulations were performed with the Eulerian chemistry transport model SILAM driven with the ERA-Interim reanalysis for 1980–2018. The Eulerian environment allowed for simultaneous application of several approaches within the same simulation and interpretation of the obtained differences. A series of sensitivity simulations revealed the role of the vertical profile of turbulent diffusion in the stratosphere, destruction of SF6 in the mesosphere, and the effect of gravitational separation of gases with strongly different molar masses. The simulations reproduced well the main features of the SF6 distribution in the atmosphere observed by the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) satellite instrument. It was shown that the apparent very old air in the upper stratosphere derived from the SF6 profile observations is a result of destruction and gravitational separation of this gas in the upper stratosphere and the mesosphere. These processes make the apparent SF6 AoA in the stratosphere several years older than the ideal-age AoA, which, according to our calculations, does not exceed 6–6.5 years. The destruction of SF6 and the varying rate of emission make SF6 unsuitable for reliably deriving AoA or its trends. However, observations of SF6 provide a very useful dataset for validation of the stratospheric circulation in a model with the properly implemented SF6 loss.

scholarly journals Simulating age of air and distribution of SF<sub>6</sub> in the stratosphere with SILAM model

2019 ◽  
Author(s):  
Rostislav Kouznetsov ◽  
Mikhail Sofiev ◽  
Julius Vira ◽  
Gabriele Stiller
Keyword(s):  
Transport Model ◽  
Direct Calculation ◽  
Passive Tracer ◽  
Chemistry Transport Model ◽  
Simultaneous Application ◽  
Separation Of Gases ◽  
Stratospheric Circulation ◽  
Tracer Accumulation ◽  
Accumulation Method

Abstract. The paper presents a comparative study of age of air (AoA) derived with several approaches: a widely used passive tracer accumulation method, the SF6 accumulation, and a direct calculation of an "ideal age" tracer. The simulations have been performed with the Eulerian chemistry transport model SILAM driven with the ERA-Interim reanalysis for 1980–2018. The Eulerian environment allowed for simultaneous application of several approaches within the same simulation, and interpretation of the obtained differences. A series of sensitivity simulations revealed the role of the vertical profile of turbulent diffusion in the stratosphere, destruction of SF6 in the mesosphere, as well as the effect of gravitational separation of gases with strongly different molar masses. The simulations reproduced well the main features of the SF6 distribution in the atmosphere retrieved from the MIPAS satellite instrument. It was shown that the apparent very old air in the upper stratosphere derived from the SF6 profile observations is a result of destruction and gravitational separation of this gas in the upper stratosphere and mesosphere. The effect of these processes add over 4 years to the actual AoA, which, according to our calculations, does not exceed 6–6.5 years. The destruction of SF6 and varying rate of emission make it unsuitable to reliably derive AoA or its trends. However, observations of SF6 provide a very useful means for validation of stratospheric circulation in a model with properly implemented SF6 loss.

scholarly journals Air-to-sea flux of soluble iron: is it driven more by HNO<sub>3</sub> or SO<sub>2</sub>? – an examination in the light of dust aging

2007 ◽  
Vol 7 (4) ◽  
pp. 10043-10063 ◽  
Author(s):  
H. Yang ◽  
Y. Gao
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
World Ocean ◽  
Global Ocean ◽  
Relative Role ◽  
Chemistry Transport Model ◽  
Acidic Gases ◽  
Relative Contribution ◽  
The World

Abstract. Aeolian dust provides the major micronutrient of soluble Fe to organisms in certain regions of the global ocean. In this study, we conduct numerical experiments using the MOZART-2 atmospheric chemistry transport model to simulate the global distribution of soluble Fe flux and Fe solubility. One of the mechanisms behind the hypothesis of acid mobilization of Fe in the atmosphere is that the coating of acidic gases changes dust from hydrophobic to hydrophilic, a prerequisite of Fe mobilization. We therefore include HNO3, SO2 and sulfate (SO42−) as dust transformation agents in the model. General agreement in Fe solubility within a factor of 2 is achieved between model and observations. The total flux of soluble Fe to the world ocean is estimated to be 731–924×109 g yr−1, and the average Fe solubility is 6.4–8.0%. Wet deposition contributes over 80% to total soluble Fe flux to most of the world oceans. Special attention is paid to the relative role of HNO3 versus SO2 and sulfate. We demonstrate that coating by HNO3 produces over 36% of soluble Fe fluxes compared to that by SO2 and sulfate combined in every major oceanic basin. Given present trends in the emissions of NOx and SO2, the relative contribution of HNO3 to Fe mobilization may get even larger in the future.

scholarly journals What can we learn about ship emission inventories from measurements of air pollutants over the Mediterranean Sea?

2009 ◽  
Vol 9 (18) ◽  
pp. 6815-6831 ◽  
Author(s):  
E. Marmer ◽  
F. Dentener ◽  
J. v. Aardenne ◽  
F. Cavalli ◽  
E. Vignati ◽  
...  
Keyword(s):  
Black Carbon ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Eastern Mediterranean ◽  
Western Mediterranean ◽  
Air Pollutant ◽  
Emission Inventories ◽  
Activity Data ◽  
The Mediterranean ◽  
Ship Emission

Abstract. Ship emission estimates diverge widely for all chemical compounds for several reasons: use of different methodologies (bottom-up or top-down), activity data and emission factors can easily result in a difference ranging from a factor of 1.5 to even an order of magnitude. Combining three sets of observational data – ozone and black carbon measurements sampled at three coastal sites and on board of a Mediterranean cruise ship, as well as satellite observations of atmospheric NO2 column concentration over the same area – we assess the accuracy of the three most commonly used ship emission inventories, EDGAR FT (Olivier et al., 2005), emissions described by Eyring et al. (2005) and emissions reported by EMEP (Vestreng et al., 2007). Our tool is a global atmospheric chemistry transport model which simulates the chemical state of the Mediterranean atmosphere applying different ship emission inventories. The simulated contributions of ships to air pollutant levels in the Mediterranean atmosphere are significant but strongly depend on the inventory applied. Close to the major shipping routes relative contributions vary from 10 to 50% for black carbon and from 2 to 12% for ozone in the surface layer, as well as from 5 to 20% for nitrogen dioxide atmospheric column burden. The relative contributions are still significant over the North African coast, but less so over the South European coast because densely populated regions with significant human activity contribute relatively more to air pollution than ships, even if these regions attract a lot of ship traffic. The observations poorly constrain the ship emission inventories in the Eastern Mediterranean where the influence of uncertain land based emissions, the model transport and wet deposition are at least as important as the signal from ships. In the Western Mediterranean, the regional EMEP emission inventory gives the best match with most measurements, followed by Eyring for NO2 and ozone and by EDGAR for black carbon. Given the uncertainty of the measurements and the model, each of the three emission inventories could actually be right, implying that large uncertainties in ship emissions need to be considered for future scenario analysis.

scholarly journals Formation of secondary organic aerosol from isoprene oxidation over Europe

2009 ◽  
Vol 9 (18) ◽  
pp. 7003-7030 ◽  
Author(s):  
M. Karl ◽  
K. Tsigaridis ◽  
E. Vignati ◽  
F. Dentener
Keyword(s):  
Secondary Organic Aerosol ◽  
Transport Model ◽  
Organic Aerosol ◽  
Formation Mechanisms ◽  
Reference Case ◽  
Chemistry Transport Model ◽  
Reference Simulation ◽  
Isoprene Oxidation ◽  
Other World

Abstract. The role of isoprene as a precursor to secondary organic aerosol (SOA) over Europe is studied with the two-way nested global chemistry transport model TM5. The inclusion of the formation of SOA from isoprene oxidation in our model almost doubles the atmospheric burden of SOA over Europe compared to SOA formation from terpenes and aromatics. The reference simulation, which considers SOA formation from isoprene, terpenes and aromatics, predicts a yearly European production rate of 1.0 Tg SOA yr−1 and an annual averaged atmospheric burden of about 50 Gg SOA over Europe. A fraction of 35% of the SOA produced in the boundary layer over Europe is transported to higher altitudes or to other world regions. Summertime measurements of organic matter (OM) during the extensive EMEP OC/EC campaign 2002/2003 are better reproduced when SOA formation from isoprene is taken into account, reflecting also the strong seasonality of isoprene and other biogenic volatile organic compounds (BVOC) emissions from vegetation. However, during winter, our model strongly underestimates OM, likely caused by missing wood burning in the emission inventories. Uncertainties in the parameterisation of isoprene SOA formation have been investigated. Maximum SOA production is found for irreversible sticking (non-equilibrium partitioning) of condensable vapours on particles, with tropospheric SOA production over Europe increased by a factor of 4 in summer compared to the reference case. Completely neglecting SOA formation from isoprene results in the lowest estimate (0.51 Tg SOA yr−1). The amount and the nature of the absorbing matter are shown to be another key uncertainty when predicting SOA levels. Consequently, smog chamber experiments on SOA formation should be performed with different types of seed aerosols and without seed aerosols in order to derive an improved treatment of the absorption of SOA in the models. Consideration of a number of recent insights in isoprene SOA formation mechanisms reduces the tropospheric production of isoprene derived SOA over Europe from 0.4 Tg yr−1 in our reference simulation to 0.1 Tg yr−1.

scholarly journals Origin, variability and age of biomass burning plumes intercepted during BORTAS-B

2014 ◽  
Vol 14 (6) ◽  
pp. 8723-8752 ◽  
Author(s):  
D. P. Finch ◽  
P. I. Palmer ◽  
M. Parrington
Keyword(s):  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Indirect Evidence ◽  
Strong Relationship ◽  
Fossil Fuel Combustion ◽  
Eastern Canada ◽  
Chemistry Transport Model ◽  
Effective Age ◽  
Black Carbon Aerosol

Abstract. We use the GEOS-Chem atmospheric chemistry transport model to interpret aircraft measurements of carbon monoxide (CO) in biomass burning outflow taken during the 2011 BORTAS-B campaign over eastern Canada. The model has some skill reproducing the observed variability (r = 0.45) but has a negative bias for observations below 100 ppb and a positive bias above 300 ppb. We find that observed CO variations are largely due to NW North American biomass burning, as expected, with smaller and less variable contributions from fossil fuel combustion from eastern Asia and NE North America. To help interpret observed variations of CO we develop an Eulerian effective age of emissions (A) metric, accounting for mixing and chemical decay, which we apply to pyrogenic emissions of CO. We find that during BORTAS-B the age of emissions intercepted over Halifax, Nova Scotia is typically 4–11 days, and on occasion as young as two days. We show that A is typically 1–5 days older than the associated photochemical ages inferred from colocated measurements of different hydrocarbons. We find that the median difference between the age measures (Δτ) in plumes (CH3CN > 150 ppt) peaks at 3–5 days corresponding to a chemical retardation of 50%. We find a strong relationship in plumes between A and Δτ (r2 = 0.60), which is not evident outwith these plumes (r2 = 0.23). We argue that these observed relationships, together with a robust observed relationship between CO and black carbon aerosol during BORTAS-B (r2 > 0.7), form the basis of indirect evidence that aerosols co-emitted with gases during pyrolysis markedly slowed down the plume photochemistry during BORTAS-B with respect to photochemistry at the same latitude and altitude in clear skies.

scholarly journals What can we learn about ship emission inventories from measurements of air pollutants over the Mediterranean Sea?

2009 ◽  
Vol 9 (2) ◽  
pp. 7155-7211 ◽  
Author(s):  
E. Marmer ◽  
F. Dentener ◽  
J. v. Aardenne ◽  
F. Cavalli ◽  
E. Vignati ◽  
...  
Keyword(s):  
Black Carbon ◽  
Atmospheric Chemistry ◽  
Air Pollutants ◽  
Transport Model ◽  
Eastern Mediterranean ◽  
Air Pollutant ◽  
Emission Inventories ◽  
Atmospheric Measurements ◽  
The Mediterranean ◽  
Ship Emission

Abstract. Ship emission estimates diverge widely for all chemical compounds for several reasons: use of different methodologies (bottom-up or top-down), activity data and emission factors can easily result in a difference from a factor of 1.5 to two orders of magnitude. Despite these large discrepancies in existing ship emission inventories for air pollutants very little has been done to evaluate their consistency with atmospheric measurements at open sea. Combining three sets of observational data – ozone and black carbon measurements sampled at three coastal sites and on board of a Mediterranean cruise ship, as well as satellite observations of atmospheric NO2 column concentration over the same area – we assess the accuracy of the three most commonly used ship emission inventories, EDGAR FT (Olivier et al., 2005), emissions described by Eyring et al. (2005) and emissions reported by EMEP (Vestreng et al., 2007). Our tool is a global atmospheric chemistry transport model which simulates the chemical state of the Mediterranean atmosphere applying different ship emission inventories. The simulated contributions of ships to air pollutant levels in the Mediterranean atmosphere are significant but strongly depend on the inventory applied. Close to the major shipping routes relative contributions vary from 10 to 50% for black carbon and from 2 to 12% for ozone in the surface layer, as well as from 5 to 20% for nitrogen dioxide atmospheric column burden. The relative contributions are still significant over the North African coast, but less so over the South European coast. The observations poorly constrain the ship emission inventories in the Eastern Mediterranean where the influence of uncertain land based emissions, the model transport and wet deposition are at least as important as the signal from ships. In the Western Mediterranean, the regional EMEP emission inventory gives the best match with most measurements, followed by Eyring for NO2 and ozone and by EDGAR for black carbon. Given the uncertainty of the measurements and the model, each of the three emission inventories could actually be right, implying that large uncertainties in ship emissions need to be considered for future scenario analysis.

scholarly journals Modelling and assimilation of lidar signals over Greater Paris during the MEGAPOLI summer campaign

2013 ◽  
Vol 13 (10) ◽  
pp. 27115-27161
Author(s):  
Y. Wang ◽  
K. N. Sartelet ◽  
M. Bocquet ◽  
P. Chazette
Keyword(s):  
Air Quality ◽  
Transport Model ◽  
Atmospheric Conditions ◽  
Chemistry Transport Model ◽  
Model Aerosol ◽  
Paris Area ◽  
The Vertical Distribution ◽  
Lidar Observations ◽  
Different Levels ◽  
New Algorithms

Abstract. In this study, we investigate the ability of the chemistry transport model (CTM) Polair3D of the air quality modelling platform Polyphemus of simulating lidar backscattered profiles from model aerosol concentration outputs. To do so, simulated lidar signals are compared to hourly lidar observations performed during the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) summer experiment in July 2009, where a ground-based mobile lidar was deployed around Paris on-board a van. The comparison is performed for six different measurement days, 1, 4, 16, 21, 26 and 29 July 2009, corresponding to different levels of pollution and different atmospheric conditions. Polyphemus correctly reproduces the vertical distribution of aerosol optical properties and their temporal variability. In the second part of this study, two new algorithms for assimilating lidar observations are presented. The aerosol simulations without and with lidar data assimilation are evaluated using the Airparif (a regional operational network in charge of air quality survey around the Paris area) database to demonstrate the feasibility and the usefulness of assimilating lidar profiles for aerosol forecasts.

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