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April 2016
Message 72

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[Met-jobs] PhD Studentship at IGN-LAREG, University Paris Diderot (France)

From Roger Brugge <r.brugge@reading.ac.uk>
To "met-jobs@lists.reading.ac.uk" <met-jobs@lists.reading.ac.uk>
Date Wed, 27 Apr 2016 19:39:05 +0000

Forwarded from CLIMLIST...

PhD Studentship on "Development of new homogenisation methods for
atmospheric GNSS data. Application to the study of climate variability."

Supervisors:
Dr. Habil. Olivier BOCK (IGN)
Dr. Emilie LEBARBIER (AgroParisTech)

Hosting institution: IGN - LAREG, University Paris Diderot, 35 rue
Hélène Brion, 75013 Paris, France

Application deadline: May 31th 2016

Project description:
Long records of observational data are essential to climate research.
Space geodetic techniques such as GNSS (Global Navigation Satellite
Systems) provide observations of tropospheric delays and integrated
water vapour for more than 20 years. However, similar to every observing
system, the global GNSS data are affected by temporal inhomogeneities
due to changes in the instruments (sensors, processing software,
measurement practice, etc.) or in measurement conditions (relocations of
instrument, change in the electromagnetic environment of the antenna,
etc.). The inhomogeneities manifest usually as artificial shifts in the
time series which can lead to erroneous interpretation as a climate
signal. It is crucial to detect and correct the inhomogeneities in long
GNSS time series before they can be used faithfully to assess climate
change and variability. The detection of artificial shift in time series
is complex because not all instrumental changes are actually documented
in logsheets, some shifts are not due to instrumental changes but to
changes in measurement conditions, and the number of stations in
continuously increasing. As a consequence, only automatic statistical
homogenisation methods can be reasonably be used.  New homogenisation
methods need to be developed to account for the statistical properties
of GNSS data.

The goals of this PhD are:
(1) to comprehensively characterize the GNSS tropospheric data (zenith
delays, gradients, and integrated water vapour) available for different
domains and periods (from regional to global); (2) model the data by
proper stochastic models and infer the optimal detection and estimation
procedures (e.g. using maximum likelihood) and implement rapid and exact
algorithms. Therefore, the methodology used by AgroParisTech for
molecular biology will be applied to develop new, innovative,
homogenisation methods for GNSS tropospheric data. The model and methods
will be tested on the basis of simulation benchmarks and compared to
more traditional approaches.
(3) Apply the algorithms on real GNSS data and use the homogenized data
to analyse the water vapour trends and variability and to validate
regional and global climate model simulations (e.g. CORDEX, CMIP5).

Collaborative framework:
This work will take place in a broad collaborative framework developed
in France between IGN and AgroParisTech and in Europe in the framework
of the COST Action ES1206 (GNSS4SWEC).
Contact for informal enquiries: Dr Olivier Bock (<Olivier.Bock@ign.fr>)

Eligibility:
Applicants for a studentship must have obtained, or be about to obtain,
a Master 2 degree or higher in sciences (mathematics, physics), if
possible specialized in geodesy and/or climatology, and with good skills
in statistics and computer programming. Good communication skills are
essential too as the candidate will join a collaborative project between
several research institutions in France and in Europe.

The three-year studentship is expected to start between 1st September
2016 and 1st December 2016 and will benefit from a stipend of 1680 € per
month during three years. The stipend can include an additional mission
of teaching, dissemination of scientific and technical information,
valuation, or expertise. In that case the stipend is raised to 2020 €
per month.

Application procedures:
Please send your application to <Olivier.bock@ign.fr> and
<emilie.lebarbier@agroparistech.fr>

The applications should clearly identify the title of the project and
include the following documents:
•    CV (including any publications)
•    Covering letter (outlining your academic interests, prior research
experience and reasons for wishing to undertake this project)
•    Transcript (this should be an interim transcript if you are still
studying)
•    Reference letter from Master study manager.
•    References from recognized personalities in the scientific field
are welcome (the references can be emailed direct to <Olivier.Bock@ign.fr>)

The closing date for applications is midnight Wednesday 31 May 2016.
Interviews are expected to take place in June. Decisions made by
Admission Committee will be communicated by 1st July 2016.



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