November 2012
Message 79

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[Met-jobs] Post-doctoral Fellow (volcanism and climate) at L-IPSL of the Institut Pierre-Simon Laplace (France)

From "Roger Brugge" <>
To "" <>
Date Tue, 27 Nov 2012 09:19:12 +0000

Forwarded from CLIMLIST...

L-IPSL post-doctoral fellow offer in volcanism and climate : volcanism
during the last millenium

The excellence laboratory L-IPSL of the Institut Pierre-Simon Laplace
offers a post-doctoral position of 2 years to address impacts of
volcanism on climate in the last millenium.

Context: It is now generally recognised that volcanic eruptions have
an important effect on climate variability from inter-annual to decadal
timescales. Using comprehensive Earth system models, much progress in
understanding volcanic climate effects have been achieved in recent
years, including the impacts on atmospheric chemistry and dynamics, on
ocean dynamics, marine and terrestrial biochemistry and on the
hydrological cycle. These results are however hampered by many
assumptions on the reconstructed past volcanic activity, but also on the
choice on sulphate aerosol size distribution and their implementation in
the radiation scheme of models themselves. Several outstanding questions
remain and concern the behaviour of huge SO_2 cloud injected into the
stratosphere after super eruptions such as those that did occur during
the last centuries.

Description of work: All in all, these results call for more
process-oriented sensitivity experiments. The challenging task for the
hired post-doctoral fellow would be to improve the actual volcanic
forcing reconstructions and its implementation in the IPSL models. As a
first step, the focus will be on the calculation of the temporal
evolution of volcanic aerosol size distribution, global fields, and
optical characteristics, for the two biggest volcanic eruptions of the
last millennium, i.e. the 1258 AD and the Tambora (1815). Such
calculations will be done with a global 2-D stratospheric climate model
including detailed microphysical and chemical processes for
stratospheric volcanic aerosols. This model has been developed at the
LATMOS laboratory (IPSL). New estimates of SO_2 release are now
available for these two eruptions and will be used to constrain the SO_2
loading in the 2-D model. This will allow the calculation of (1)
consistent evolution of the global distribution and size of
stratospheric sulphate aerosols after each eruption and (2) deduce the
related optical properties (AOD, single scattering albedo and parameters
of asymmetry) for both v/isible/ and /infrared /spectral bands.

In a second step and in collaboration with LMD laboratory (IPSL), the
deduced new size distribution and optical parameters will be implemented
into the LMDz radiation scheme for both spectral bands (visible and
infrared). Sensitivity experiments with chemistry-climate models (CCM),
LMDz-REPROBUS and/or LMDz-INCA, coupled to NEMO, including the new
stratospheric aerosol radiation schemes will then be used to run
sensitivity experiments and evaluate the impact of competing non-linear
radiative and chemical processes on the simulated climates for volcanic
eruptions. We will start by a test case, simulating the Mont Pinatubo
eruption in the CCM model. The results will be validated against the
large datasets of observations (satellite, balloon, reanalysis,…) and
serve as a reference control run. Then we will tackle the two biggest
volcanic eruptions for the last millennium (i.e. 1815, 1258 AD).

In the last step, cross validations of the sensitivity experiments for
the mega eruptions with proxy data will be essential to better evaluate
the realism of the new volcanic forcing parameterisation for the largest
eruptions. More proxy reconstructions are now available at IPSL (LSCE,
LOCEAN, etc.) and in other national and international laboratories. They
will help constrain the climate sensitivity. In interaction with the
LOCEAN laboratory (IPSL), further tests will be required on the
influence of the initial state (including the ocean) on the simulated
climatic response following these volcanic eruptions before extending
our approach to the whole millennium.

Supervision team : The work will be conducted under the main
supervision of M. Khodri (LOCEAN), in close connection with other
researchers : M. Marchand (LATMOS), S. Bekki (LATMOS), O. Boucher (LMD),
J. Mignot (LOCEAN), D. Swingedouw (LSCE). The work will be mainly
conducted at LOCEAN, but in other IPSL sites also.

Duration and salary:The post-doctorate will be recruited for 24 months
with a net monthly salary around 2000 euros, commensurate with
experience. This includes social services and health insurance.

Contact for applications:Applications should include a vita, a
statement of research interests and the names of at least two references
including e-mail addresses and telephone numbers. Applications should be
submitted by e-mail to Myriam Khodri (<>).

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