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 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 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 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 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.

The Role of the Snowpack on the Fate of α-HCH in an Atmospheric Chemistry-Transport Model

2008 ◽  
Vol 42 (8) ◽  
pp. 2943-2948 ◽  
Author(s):  
Kaj M. Hansen ◽  
Crispin J. Halsall ◽  
Jesper H. Christensen ◽  
Jørgen Brandt ◽  
Lise M. Frohn ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Chemistry Transport Model

scholarly journals Transport mechanisms for synoptic, seasonal and interannual SF<sub>6</sub> variations in troposphere

2008 ◽  
Vol 8 (4) ◽  
pp. 12737-12767 ◽  
Author(s):  
P. K. Patra ◽  
M. Takigawa ◽  
G. S. Dutton ◽  
K. Uhse ◽  
K. Ishijima ◽  
...  
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Sulfur Hexafluoride ◽  
Transport Model ◽  
Circulation Model ◽  
Chemistry Transport Model ◽  
Transport Component ◽  
Interhemispheric Transport ◽  
Insight Into

Abstract. We use an atmospheric general circulation model (AGCM) driven Chemistry-Transport Model (ACTM) to simulate the evolution of sulfur hexafluoride (SF6) in the atmosphere. The model results are compared with continuous measurements at 6 sites over 71° N–90° S. These comparisons demonstrate that the ACTM simulations lie within the measurement uncertainty over the analysis period (1999–2006) and capture salient features of synoptic, seasonal and interannual SF6 variability. To understand transport timescales of SF6 within the troposphere, transport times of air parcels from the surface to different regions of the troposphere ("age") are estimated from a simulation of an idealized tracer. Monthly-mean, 2-box model exchange times (τex) are calculated from both the observed and simulated SF6time series at the 6 observing sites and show favorable agreement, suggesting that the model adequately represents large-scale interhemispheric transport. The simulated SF6 variability is further investigated through decomposition of the mixing ratio time-tendency into advective, convective, and vertical diffusive components. The transport component analysis illustrates the role of each process in SF6synoptic variability at the site level and provides insight into the seasonality of τex.

scholarly journals Variability of springtime transpacific pollution transport during 2000–2006: the INTEX-B mission in the context of previous years

2010 ◽  
Vol 10 (3) ◽  
pp. 1345-1359 ◽  
Author(s):  
G. G. Pfister ◽  
L. K. Emmons ◽  
D. P. Edwards ◽  
A. Arellano ◽  
T. Campos ◽  
...  
Keyword(s):  
Transport Model ◽  
Pollution Transport ◽  
Chemistry Transport Model ◽  
Pollution Levels ◽  
Annual Variability ◽  
Source Regions ◽  
Time Period ◽  
The Pacific ◽  
The Us ◽  
Transport Experiment

Abstract. We analyze the transport of pollution across the Pacific during the NASA INTEX-B (Intercontinental Chemical Transport Experiment Part B) campaign in spring 2006 and examine how this year compares to the time period for 2000 through 2006. In addition to aircraft measurements of carbon monoxide (CO) collected during INTEX-B, we include in this study multi-year satellite retrievals of CO from the Measurements of Pollution in the Troposphere (MOPITT) instrument and simulations from the chemistry transport model MOZART-4. Model tracers are used to examine the contributions of different source regions and source types to pollution levels over the Pacific. Additional modeling studies are performed to separate the impacts of inter-annual variability in meteorology and dynamics from changes in source strength. Interannual variability in the tropospheric CO burden over the Pacific and the US as estimated from the MOPITT data range up to 7% and a somewhat smaller estimate (5%) is derived from the model. When keeping the emissions in the model constant between years, the year-to-year changes are reduced (2%), but show that in addition to changes in emissions, variable meteorological conditions also impact transpacific pollution transport. We estimate that about 1/3 of the variability in the tropospheric CO loading over the contiguous US is explained by changes in emissions and about 2/3 by changes in meteorology and transport. Biomass burning sources are found to be a larger driver for inter-annual variability in the CO loading compared to fossil and biofuel sources or photochemical CO production even though their absolute contributions are smaller. Source contribution analysis shows that the aircraft sampling during INTEX-B was fairly representative of the larger scale region, but with a slight bias towards higher influence from Asian contributions.

scholarly journals The On-Line Integrated Mesoscale Chemistry Model BOLCHEM

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 192
Author(s):  
Rita Cesari ◽  
Tony Christian Landi ◽  
Massimo D’Isidoro ◽  
Mihaela Mircea ◽  
Felicita Russo ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Transport Model ◽  
Horizontal Resolution ◽  
Integration Step ◽  
Chemistry Transport Model ◽  
European Environmental Agency ◽  
On Line ◽  
One Year ◽  
Pm2.5 And Pm10 ◽  
Monitoring Service

This work presents the on-line coupled meteorology–chemistry transport model BOLCHEM, based on the hydrostatic meteorological BOLAM model, the gas chemistry module SAPRC90, and the aerosol dynamic module AERO3. It includes parameterizations to describe natural source emissions, dry and wet removal processes, as well as the transport and dispersion of air pollutants. The equations for different processes are solved on the same grid during the same integration step, by means of a time-split scheme. This paper describes the model and its performance at horizontal resolution of 0.2∘× 0.2∘ over Europe and 0.1∘× 0.1∘ in a nested configuration over Italy, for one year run (December 2009–November 2010). The model has been evaluated against the AIRBASE data of the European Environmental Agency. The basic statistics for higher resolution simulations of O3, NO2 and particulate matter concentrations (PM2.5 and PM10) have been compared with those from Copernicus Atmosphere Monitoring Service (CAMS) ensemble median. In summer, for O3 we found a correlation coefficient R of 0.72 and mean bias of 2.15 over European domain and a correlation coefficient R of 0.67 and mean bias of 2.36 over Italian domain. PM10 and PM2.5 are better reproduced in the winter, the latter with a correlation coefficient R of 0.66 and the mean bias MB of 0.35 over Italian domain.

Past climate and the role of ocean heat transport: Model simulations for the Cretaceous

1993 ◽  
Vol 8 (6) ◽  
pp. 785-798 ◽  
Author(s):  
Eric J. Barron ◽  
William H. Peterson ◽  
David Pollard ◽  
Starley Thompson
Keyword(s):  
Heat Transport ◽  
Transport Model ◽  
Ocean Heat Transport ◽  
Past Climate ◽  
Model Simulations
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