|From||Alain Hauchecorne <firstname.lastname@example.org>|
|Date||Fri, 30 Mar 2018 10:52:41 +0200|
|PhD opportunity at LATMOS, University Paris-Saclay, Guyancourt, France|
TITLE: STUDY OF GLOBAL ATMOSPHERIC GRAVITY WAVES CHARACTERISTICS USING ESA AEOLUS SATELLITE WIND OBSERVATIONS
Alain HAUCHECORNE (LATMOS, CNRS), email@example.com
+33 1 80 28 50 24 / +33 6 43 64 94 56
LATMOS, UVSQ, 11 Boulevard d’Alembert, 78280 Guyancourt, France
Sergey KHAYKIN (LATMOS, UVSQ Paris-Saclay), firstname.lastname@example.org
+ 33 1 80 28 52 06
Keywords : wind measurements, gravity waves, spaceborne lidar
Profile and skills required
· Good knowledge of atmospheric physics and dynamics
· Skills in data processing
· Experience in data analysis languages like Matlab, IDL
Understanding and predicting the evolution of global climate strongly relies on the knowledge of dynamical processes in the middle atmosphere such as atmospheric waves. Since the global atmospheric circulation is largely driven by middle atmosphere dynamics, it is essential that the climate models take a proper account for the dynamical processes, which has not been fully understood yet. Small- scale atmospheric waves, called internal gravity waves (IGWs) pose a particular challenge for models, whereas inaccurate parameterization of IGWs can dramatically bias the predictions of future atmospheric circulation changes. This issue is aggravated by insufficient understanding of IGW sources, propagation and dissipation, but above all by the lack of observations of wind in the stratosphere. Indeed, spatially sparse radiosoundings are essentially the only source of data on stratospheric wind profiles. With that, they only provide a “snapshot” of the local atmospheric conditions therefore missing important IGW parameters.
European Space Agency’s Aeolus satellite mission is designed to provide global information on the wind speed from the ground up to 30 km, which is highly demanded for weather forecasting. Aeolus satellite is planned to be set into orbit in May 2018 and its payload will consist of a sophisticated ALADIN lidar instrument measuring wind velocity by sensing Doppler spectral shift of the laser echo scattered by the different layers of the atmosphere. Aeolus global-scale wind measurements are expected to be of great value for studying the dynamical processes in the stratosphere.
The primary objective of this doctoral project is to explore and quantify the capacities of Aeolus observations in capturing and resolving dynamical processes such as IGWs at various spatial and temporal scales. The work will consist first of all in geophysical analysis of Aeolus wind profiles for deriving IGW parameters such as horizontal and vertical wavelengths, energy and momentum flux. The retrieved parameters and their variability in time and space will be compared with those derived from global temperature profiling data of GPS radio occultation missions such as GRAS onboard MetOp satellites. Another task will be to validate the quality of Aeolus wind measurements using the two French ground-based Doppler lidars operating at a mid-latitude site (Observatoire de Haute-Provence, OHP) and at a south tropical site (Maïdo Observatory Reunion Island). The time-resolved wind measurements by ground-based lidars will also be used for IGW analysis. An important outcome of this doctoral project will be the first ever climatology of IGW parameters based on a combination of global-coverage wind and temperature profiling.
The space lidar ADM-Aeolus from the European Space Agency (ESA) will be launched in September 2018. It will provide wind It will provide wind profiles at the global scale from the surface to 30 km altitude. It will be the first space instrument to measure the wind by lidar from space. The two ground-based lidars at OHP and Maïdo are the only instruments allowing the validation of ADM-Aeolus data in the stratosphere. They are integrated in the Calibration/Validation (CalVal) team of ADM-Aeolus setup by ESA.
The objectives of the thesis will be to validate ADM-Aeolus data in the upper troposphere-stratosphere by intercomparison with ground-based wind lidar data at OHP and Maïdo for the study of atmospheric gravity waves at global scale. The thesis will be also based the exploitation of ground-based lidar data for the study of atmospheric gravity waves.
Financial and material conditions
The funding of the PhD grant is secured for 3 years through a CIFRE convention (http://www.anrt.asso.fr/fr/cifre-7843) with Gordien Strato, a small high-tech company dedicated to the development and valorisation of atmospheric lidars.The candidate will benefit at LATMOS from the computing resources necessary for his thesis work and will have access to the databases of ground-based and spaceborne lidars.
Publications in peer-reviewed international journals; presentations in international scientific congresses
This project is part of an international collaboration in the context of the Cal/Val of the ADM-Aeolus satellite. The LATMOS is part of the Cal/Val French team selected by the European Space Agency.
Opening to the industrial world
The funding of the thesis grant by Gordien Strato gives an opening to the industrial world in the fields of high-tech scientific instruments and modeling for the atmospheric studies.
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