POSTDOCTORAL POSITION OPENING
Funded by CNRS/France
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Heading of offer:
THE WEST AFRICA LOW TROPOSPHERE DURING THE MONSOON ONSET
Responsible : Bernard Campistron (physicist)
Opening date: 1st September or 1st October 2007
Application deadline: 30 April 2007
Laboratory : Laboratoire d’Aérologie (LA), Observatoire Midi Pyrénées, Toulouse, France.
Location: Centre de Recherches Atmosphériques (Lannemezan, 65, France). Possible lodging inside the
campus of the Center.
Gross salary : 2500 Euros
Duration: 1 year (at most renewable one time)
The selection committee will be held around May 15th.
Research Project :
This research project is part of the AMMA experiment which is concerned with the
investigation of the West Africa Monsoon. During the enhanced observation period (EOP),
covering the 2006 dry and wet seasons, a network of wind profiler radars were operated
in the AMMA domain. In particular at Djougou Bénin, one of the AMMA field campaign
super-sites, a UHF and a VHF radar worked continuously during several months providing
vertical profiles of the mean and turbulent atmospheric dynamics every 15 min from 100
m above ground up to 12 km on the average. These remote sensing devices were associated
with other facilities such as the complete energy fluxes measurement at the ground
which allow for the first time to document during the dry and wet season the lower
atmosphere and the meteorological processes associated with the monsoon and the
convective systems. Thus, the objective of the proposed study is to quantify at
different scales the role of different mechanisms responsible of the observed spatiotemporal structure of the West Africa monsoon.
At least four atmospheric mechanisms are related to this thematic. The first one is
concerned with the atmospheric and surface interaction which plays a major role in the
triggering and feeding of the convective systems. The response of the atmospheric
boundary layer (ABL) to the surface forcing, affected itself by rainy events or
dryness, can be deduced through its vertical development and the associated turbulence.
The second mechanism is related to the ensemble of phenomena of the ABL dynamic (such
as coherent structures, nocturnal low level jet...) that transfers energy to the free
atmosphere and feed the convection. The entrainment that occurs in the interface layer
between the low levels cool and humid monsoon flow and the overlying dry and warm
Harmattan wind is the third mechanism to investigate. Its impact on the convection
initiation during the monsoon onset at the end of the boreal spring will be evaluated.
The role of the strong wind shear in this transition layer on the entrainment and
convection will be considered. At last, the fourth mechanism linked to the jet streams
aloft such as the Africa Easterly Jet, the interactions of which with the lower levels
are yet not well understood, deserve a special interest as they are well documented by
the wind profilers.
Eventually, the proposed study, based on an exceptional data set covering several
seasonal cycles will be integrated in a numerical modelling effort supported by the
host research group (MESO-nh numerical model) and through collaborations (CNRM
laboratory of the French Metoffice).
Requirements
The candidate must have a PhD in meteorology or atmospheric sciences obtained for less
than 2 years. The work is based mainly on the use and processing of wind profiler
radars and surface energy budgets measurements. Knowledge on remote sensing techniques
is not essential but hard desirable. A good skill in a computer programming language
(FORTRAN, MATLAB ...) is mandatory.
Applications :
Applications should include CV , support letters and motivation letter and should be sent to
Bernard Campistron, CRA, 8 route de Lannemezan, 65300 Campistrous, France.
e-mail: camb@aero.obs-mip.fr. Tel: ( 33) [0] 5 62 40 61 04