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Arctic air pollution : future perspectives

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Arctic air pollution : future perspectives Empty Arctic air pollution : future perspectives

Message  kslaw Lun 22 Avr - 7:09

Chères et chers collègues,

Atmospheric pollution (ozone, aerosols and their precursors) in the Arctic originates primarily from mid-latitude emission regions but also has local sources which are likely to increase in the future due to global warming and economic drivers. It is important to quantify their impacts on regional air quality and climate.

The contribution of different sources to Arctic pollution still remains uncertain despite significant advances, in particular, as a result of field campaigns which took place during the International Polar Year in 2008 (e.g. POLARCAT-France, ARCTAS, ISDAC), and subsequent analysis/data collection that is still on-going (e.g. ANR-CLIMSLIP - http://www.latmos.ipsl.fr/index.php/fr/tact/themes-de-recherche/climslip, LIA YAK-AEROSIB, https://yak-aerosib.lsce.ipsl.fr/doku.php ) involving groups from several laboratories (LATMOS, LaMP, LSCE, LGGE, LMD). Local anthropogenic emissions in the Arctic may be playing a more significant role (direct and indirect effects) than previously appreciated, and are likely to increase substantially in the near to mid-term future. Changing natural aerosols as well as methane also need to be taken into consideration.

With this in mind, we have identified 2 research areas which we feel merit further discussion in the French community as part of the Chantier Arctique prospective:

Local Arctic Pollution:
Given the very rapid nature of climate change in the Arctic and global economic pressures, accelerated industrialization in the Arctic is already underway with summer maritime sea routes along the Northern Sea Route already open, and strong interest in oil/gas and mineral exploration in Alaska, Greenland and northern Eurasia. Construction of polar class ships, which can penetrate summer sea-ice across the North Pole, has already been evoked. Local emissions already appear to be influencing atmospheric composition and climate in the Arctic (e.g. flaring and domestic combustion emissions of black carbon in Eurasia, cruise shipping in Svalbard). Significant growth in local sources, together with increased growth in infrastructure, industrialization and/or urbanization, are likely to impact concentrations of trace gases and aerosols and thus, regional air quality and/or climate.

Given the significant uncertainties which exist in quantifying current and future emissions from shipping, oil/gas extraction, metal smelting, mining, domestic combustion as well as boreal/agricultural fires in the Arctic, a combination of local-scale and regional modelling, analysis of existing data (e.g. from EU ACCESS project (www.access-eu.org), ground-based, satellite) and new field data is needed. In particular, an aircraft campaign, using an aircraft from the French fleet, could be used to improve quantification of local emissions and regional budgets. The aircraft, equipped with a full aerosol and trace gas payload, could be based in, for example, northern Scandinavia/ Spitzbergen. It will also be important to take into consideration unique Arctic photochemistry, such as the presence of halogens or snow emissions, which can influence the Arctic oxidising capacity, particularly in the boundary layer where local emissions are occurring. An aircraft equipped with remote sensing instruments (radar and lidar) could also be used for aerosol and cloud studies. A campaign with the Russian YAK aircraft could also be dedicated to these issues since some of the largest uncertainties surround local emissions in Siberia and northern Russia (e.g. fires, smelting, flaring, domestic emissions). New data would be used to improve the representation of emissions and aerosol/trace gas processing in regional/global models as well as to improve emission inventories used for predicting future composition and climate. These data will also help to better understand the impact of pollution on clouds and radiative processes.

Air Pollution Sources in the High Arctic:
Significant changes are currently underway in the Arctic Ocean, in particular, the decline of the summer sea-ice with significant reductions in volumes/extend reported. The role of pollutants, and in particular aerosols, in Arctic warming is currently poorly quantified due to a lack of knowledge about important processes and their treatment in models. In particular, there is a lack of information about the vertical distribution of trace gases, aerosols and their speciation as well as cloud microphysics in the high Arctic (>75N) with previous airborne campaigns focusing largely on more southerly Arctic latitudes. Cloud properties related to pollution aerosols are also poorly quantified and new field experiments would benefit from up to date microphysical and remote sensing airborne measurements recently developed in France. A combination of airborne radar/lidar measurements could be used to document aerosols and mixed-phase clouds. Satellite data (e.g. CALIPSO-CloudSat, EarthCare, IASI, GOSAT) can provide additional information (up to 82N for CALIPSO), including regions of pollutant import, but further work is required on retrievals at high latitudes. New developments, as part of the Equipex IAOOS project (http://www.iaoos-equipex.upmc.fr/, 2011-2019), are also underway such as the addition of aerosol micro-lidars to ocean-atmosphere buoys that will be deployed in the Arctic Ocean from 2014/15 and can provide contextual information about cloud/aerosol distributions. Other new approaches could also be envisaged, such as the use of unmanned aerial vehicles (UAVs), as well as the development of new airborne sensors.

A combined approach, based on new field measurements, regional/global modelling and analysis of satellite data, is needed to improve our understanding about the role of pollutants (aerosols, ozone) and feedback processes in the high Arctic. An aircraft campaign using the French aircraft fleet, based in Spitzbergen or Greenland, for example, could be used to collect data on vertical distributions over the Arctic Ocean, in the vicinity of pollutant import regions linking to the IAOOS buoy network and to validate satellite data. The data would be used to improve our understanding about radiative effects and impacts on clouds, and the treatment of such processes in models leading to improved climate predictions. Such an initiative could also contribute to international plans under development as part of the International Polar Initiative (IPI) (http://internationalpolarinitiative.org/) focusing on improving seasonal and climate predictability in the Arctic.

We look forward to discussing these ideas in the French community and welcome any comments or feedback.

Kathy Law, Gerard Ancellet, Jacques Pelon, Jennie Thomas, Jean-Christophe Raut, Cyrille Flamant, Francois Ravetta, Claire Granier, Cathy Clerbaux, Julien Delanoë, Sébastien Payan


Messages : 6
Date d'inscription : 12/03/2013

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Arctic air pollution : future perspectives Empty Access to the Arctic Ocean

Message  Hans-Werner Jacobi Ven 26 Avr - 9:39

The activation of reactive halogen compounds possibly exerts
the strongest direct link between the sea ice and atmospheric chemistry. More
than 20 years of satellite observations have indicated the regular formation of
bromine oxide in springtime over the Arctic Ocean. Under certain conditions
bromine oxides and possibly other reactive halogen compounds are generated from
sea salt. The halogens have a profound impact on the composition of the
atmosphere leading to the removal of normally ubiquitous ozone and mercury in
the atmospheric boundary layer. At all Arctic coastal stations ozone and
mercury depletion events have been observed regularly. However, the very few
direct measurements of ozone over the sea ice have indicated that the
springtime removal of ozone is more persistent over the Arctic Ocean and
concerns possibly the entire Arctic ocean. The long history of ozone and
mercury observations in the Arctic indicate a complex interplay of chemical,
meteorological, and sea ice conditions for the chemical activation of the
halogens. Nevertheless, the exact conditions still remain unclear. Further in
situ observations in springtime in the boundary layer over the sea ice in
combination with advanced retrievals using remote sensing data are necessary to
improve our understanding of the underlying processes. Only with this knowledge
a better prediction of the impact of the halogens on air quality, short- or
long-lived greenhouse gases like ozone and methane and pollutants like mercury
will be possible.

To perform in situ observations and measurements of
the vertical distribution of reactive species access during all seasons to the
sea ice-covered regions of the Arctic Ocean is urgently needed using ice camps,
ice breakers, and airborne instruments. Instruments and techniques to perform
such measurements have been developed by several French groups and are ready to
be used in the Arctic. Such detailed studies are complementary to satellite
observations and measurements potentially performed within a network of
autonomous buoys and to measurements performed at coastal stations.

Hans-Werner Jacobi

Messages : 9
Date d'inscription : 12/03/2013

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Arctic air pollution : future perspectives Empty Characterisation of anthropogenic aerosols and their interactions with clouds in the Arctic.

Message  EJFreney Mar 30 Avr - 16:11

Contributions from the
Laboratoire de Meteorologie physiques (LaMP).

Several recent studies have
highlighted that the Arctic is warming twice as fast as the rest of the Earth. This
has resulted in the shrinking of the Arctic ice sheet and thereby opening up
new shipping channels that were not previously available. The increase in shipping
channels and the consequent
urbanization results
in an increase in local emissions that can have important implications on
aerosol properties and their interactions with clouds (liquid and ice phase).
It is thought that aerosol
direct (absorption by black carbon) and indirect (aerosol cloud interactions) effects
are likely to play a large role in the rapidly changing Arctic climate. In
addition to lo
cal sources, polluted air masses are transported over long-distances
that lead to the formation of the Arctic Haze, containing high concentrations
of absorbing aerosol particles.

Predictions of climate warming
in the Arctic from models are considerably lower than observations, thereby
highlighting the need to carry out experiments dedicated to understanding the influence
of anthropogenic emissions in the Arctic environment, and how these emissions
affect the interactions between aerosol particles and clouds. Although there are
an increasing number of ground-based studies, few aircraft observation studies
have performed detailed chemistry measurement of aerosol particles in the Arctic.
Aircraft studies are one of the most efficient methods to characterize the
influence of different air-masses and local sources on the Arctic environment,
characterising the evolution of aerosol particles as they leave the source and
mix with background air-masses. In addition, they provide a means to
characterize the vertical profile of the chemical and physical properties of
both gas and aerosol particles.

The LaMP has three airborne
racks that are equipped with a suite of ATR-42 (SAFIRE) certified
instrumentation including the C-ToF-AMS (particle chemistry), SMPS and CPC
(size distribution measurements), volatility measurements, and impactor stages
for offline analysis with electron microscopy. This combination of instruments
allows us to characterize the chemical and physical properties of aerosol
particles with timescales of less than 1 minute. The combination of CPCs and
SMPS provides us with aerosol particle number concentration of aerosol particles
as small as 5 nm, providing important information on new particle formation
events (NPF). NPF events (nucleation) can contribute up to 50% to cloud condensation
nuclei in the atmosphere, making it essential to characterize the meteorological
conditions under which they form. Electron microscopy can provide detailed
information on aerosol composition, morphology, and mixing state which is
essential to understand aerosol cloud interactions, and is especially useful in
understanding the formation of ice crystals.

In addition to airborne
measurements, ground based in-situ measurements of aerosol particle chemical
and physical properties, together with cloud condensation nuclei measurements can
provide a means to carry out extended studies using additional instrumentation that
can not be airborne. This extended set-up will allow for process studies in the
very specific conditions of the arctic environment. In particular, ship
emissions containing high content of sulfur can lead to large numbers of new particles,
that in turn may influence cloud optical properties.

Freney, Karine Sellegri, Olivier Jourdan, Aurelie Colomb, Alfons Schwarzenböck


Messages : 4
Date d'inscription : 30/04/2013

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Arctic air pollution : future perspectives Empty Integrated understanding of natural and anthropogenic cycling

Message  raut Ven 17 Mai - 13:45

The Arctic is a region that exhibits
unique atmospheric chemistry - due to the import of pollution from
long distances into the region, chemical transformations at the
ice/ocean-atmosphere surface, and the changing nature of the Arctic
region (e.g. reduction in Arctic sea ice during summer). As pointed
out in this discussion, one chemical process that demonstrates the
unique nature of the Arctic region is the occurrence of ozone
depletion events that can be attributed to photochemical halogen
activation from ice, snow, and/or aerosol particles during spring and
summer. In addition, understanding the activation and cycling of
deposited nitrogen in surface snow is critical for understanding
Arctic tropospheric chemistry as well as for interpreting the ice
core record of nitrate.

The natural and anthropogenic chemical
cycles occurring in the Arctic region are not separate and must be
studied in an integrated way by combining both new observations and
model developments. The aim should be to advance our understanding
of the processes that determine current Arctic tropospheric
composition. New observations including gas and aerosol chemical
composition, as well as cloud properties, are extremely important for
developing predictive chemical transport models for this region. In
addition, processes currently missing from most models (for example
halogen chemistry, snow emissions of nitrogen oxides) need to be
included for models to adequately describe current Arctic
tropospheric chemical composition. Heterogeneous processing on
aerosols also requires improvements in models. These advances are a
critical step in predicting how environmental change will impact
tropospheric chemical cycling in this region.

We are looking forward to working with
colleagues to make new measurements in the Arctic region and to use
these measurements to understand natural and anthropogenic chemical
cycles and to improve model predictions of these processes.

Jennie Thomas, Jean-Christophe Raut,
Kathy Law, Gerard Ancellet, Jacques Pelon (LATMOS)


Messages : 3
Date d'inscription : 04/05/2013

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