My research is focused on improving our understanding and quantification
of trace gas emissions and transport in the troposphere.
For this purpose, I am using an approach integrating available observations -
both in situ and satellite data - with chemistry and transport
I am currently involved in three main projects:
| Analysis of the long range transport of pollution in the Northern Hemisphere
|Air quality is not
only a local problem. Trace gases and aerosols emitted in a specific
region may be transported on long distances depending on their
lifetimes, and affect air quality in a neighbouring region. This
transport of pollution may have several impacts: an increase of
pollution backgroung levels at the surface; an import of pollution
plumes to the boundary layer, directly altering air quality; a
modification of the background levels in the free troposphere, with
implications for the radiative budgets.
observations from satellite-borne instruments are particularly well
suited for the analysis of the transport pathways. The controling
mechanisms and the related impacts are analysed using
simulations. Howere, they are currently unable to accurately represent
due to uncertainties at different levels (emissions, transport
mechanisms, chemical evolution).
Specific objectives: analyse the current biases
in the simulation of several trace gases (CO for example) compared to
the available in situ and satellite observations (IASI in particular).
One of the main aspects is the simulation of the influence of wildfires.
Approach: I am using the LMDz-INCA global model
and comparisons to the campaign in situ observations (POLARCAT in 2008,
ICARTT in 2004) but also to the available satellite observations
(IASI/METOP in particular since 2006).
LRT from Asia as viewed from satellite (top) and as
simulated by the LMDz-INCA global model (bottom).
(Turquety et al., ACP, 2008)
Related projects: I am currently involved in the POLARCAT and follow-on CLIMSLIP project (Climate impacts of short-lived pollutants in the polar regions),
which aim at better understanding the transport of pollution towards
the Arctic, one of the regions most sensitive to climate change. This
region undergoes the influence from the large industrialized regions of
the Northern Hemisphere (North America, Europe, Asia), regularly
resulting in the so-called "Arctic Haze", but also of the large fires
burning in the boreal forests during summer. This work follows previous
analyses done in the framework of the ICARTT international campaign
(2004) during my post-doc at Harvard University.
(Main collaborations: LSCE, LATMOS)
| Fire emissions and transport
Wildfires are one
of the main sources of trace gases and aerosols. However, their impact
remains poorly quantified due to uncertainties on their emissions, but
also on their transport - and in particular on possible importance
of pyro-convective events - and on the chemical evolution during
the long range transport (ozone production, interactions between ozone
Sudies at global scale for the impact of boreal fires; at regional scales in the Euro-Mediterranean region (APIFLAME project) and Mexico (Thesis S. Stromatas).
the current inventories of fire emissions and develop a method for an
accurate evaluation in near-real time to support air quality
- analyse the possible importance of pyro-convection;
- study the evolution of the characteristics of fire plumes during the transport.
Approach: Global modeling using the LMDz-INCA global model
and regional modeling using the CHIMERE model; with here again comparisons to the campaign in situ observations but also to the available satellite observations
| Analysis and Prediction of the Impact of Fire pLumes on Air quality of the Mediterranean and Europe (APIFLAME)
Forest fires are regularly burning thousands of hectares of
vegetation in Europe (mainly Southern Europe, Portugal, Spain, Greece,
etc.), strongly affecting local ecosystems and economies, but also air
quality since vegetation
burning is a major source of trace gases and aerosols. As a lot
of the species emitted have a long enough lifetime to allow long range
transport, emissions may have significant regional impact on
atmospheric composition. However, this impact remains poorly quantified
due to large uncertainties on the emissions (extent of the areas burnt,
type of vegetation burned and efficiency of the burning, emission
factors for the chemical species, etc.), but also on the export
processes and chemical evolution of the pollution plumes.
aims at evaluating and improving simulations -- and thereby
quantification -- of the impact of fires on air quality, using the
CHIMERE regional pollution model and available observations. A
particular attention will be given to the analysis of the trace gas and
aerosol observations from satellite remote sensors (IASI/METOP and
A-Train instruments CALIOP/CALIPSO and POLDER/PARASOL) which provide
good horizontal and temporal coverage. Results from this project will
allow the integration of this potentially extremely high pertubation in
air quality forecasting systems (e.g. Prev'Air plateform at
|IASI monitoring of CO in the pollution plume emitted by the record-breaking fires in Greece in August 2007:
(Turquety et al., Atmosph. Chem. Phys., 2009)
APIFLAME is funded by the
French program PRIMEQUAL and coordinated by S. Turquety,
LMD/IPSL. Partners: CEREA, INERIS, LA, LATMOS/IPSL, LOA, LSCE/IPSL.
For more info, please visit the project web page .
| Trace gas retrieval from the high
resolution infrared sounders IASI
In the recent years, several satellite
missions measuring the thermal infrared radiation emitted by the Earth-atmosphere system in a nadir viewing geometry
have demonstrated the
capabilities of such measurement technique for global monitoring of atmospheric
composition (MOPITT, AIRS, TES, IASI). Combining high spectral resolution with improved spatial and
temporal coverage for more accurate view of regional and local pollution will be
the major objective of future missions.
I am more particularly involved in the analysis of observations by the Infrared Atmospheric Sounding
Interferometer (IASI), a CNES/EUMETSAT instrument. It is a nadir viewing FTS recording high resolution IR
spectra with a daily global coverage and a 25 km horizontal sampling,
mounted on the European Polar System METOP satellites. The first of three successive
platforms was launched in
October 2006. The two following will be launched sequentially over a period of 14 years, allowing the monitoring of the evolution of the composition of the
Specific objectives :
now use these retrievals in collaboration with LATMOS and ULB for
scientific studies of the LRT of pollution. I also contribute to the
analysis of information content for pollution studies.
I have contributed to the development of several software for the retrieval of trace gases from IASI spectra:
A near-real time retrieval algorithm based on neural networks (Turquety et al., JGR, 2004) (ozone retrieval module developed during my PhD at Service d'Aéronomie, now LATMOS);
- Research algorithm based on the optimal estimation method, the Atmosphit software developed at ULB, used for the retrieval of any IR absorbing species (Coheur et al., JGR, 2005; Barret et al., ACP, 2005);
version based on OEM: the FORLI softwares developed at ULB. I
particularly contributed to the development of the FORLI-CO algorithm,
for the retrieval of carbon monoxyde (Turquety et al., ACP, 2009).
Research projects :
work is undertaken as part of the CNES-TOSCA project "Use of IASI
observations for atmospheric chemistry" led by C. Clerbaux (LATMOS).