|From||Roger Brugge <firstname.lastname@example.org>|
|Date||Mon, 3 Apr 2017 18:31:34 +0000|
Forwarded from CLIMLIST... Dear Colleagues, The Laboratory Atmosphere and Spaceborne Observations (LATMOS, France) is seeking a motivated PhD student to work on the tropical atmospheric water cycle. The tentative title of the thesis is "Climate sensitivity of the tropical atmospheric water cycle : use of a constellation of satellites for the definition of new metrics" General Context: The World Climate Research Program (WCRP) recently highlighted the need to improve the understanding of processes linking clouds, circulation of atmospheric water and climate: reducing uncertainties in these processes is a key issue to anticipate the climate changes that are based on numerical models (Bony et al., 2015). Considering the processes involved, it is important to know that interactions between water vapor, clouds, precipitation, and radiation (shortwave and infrared) in the tropical troposphere are particularly complex. They are expressed in small (microphysics) and medium (tens of kms) spatial and temporal scales under the influence of the large-scale atmospheric circulation, which they influence in return. Cloud formation, vertical deployment and life cycle are the result of mixed processes involving the thermodynamics of the atmosphere (clear and cloudy), radiative exchanges (solar and thermal infrared) and atmospheric dynamics, from small-scale turbulence to large-scale circulation cells. These interactions are difficult to understand, and the description of processes differs from one climate model to another. However, the analysis of climate sensitivity, ie its adjustment in response to radiative forcing, such as anthropogenic disturbances of greenhouse gas concentrations, requires intense use of numerical models of climate. In the same way, the feedback mechanisms between the different processes are mainly analyzed via this type of model. Unfortunately, at the moment these models do not converge towards a single behavior and propose a wide range of projections (IPCC, 2013). This leads to predictions of uncertain climate changes varying significantly from a climate model to another one for the same socio-economic scenario. Moreover, these climate sensitivity estimates are generally based on partial derivatives of parameters which can not be rigorously translated into the observations, and the feedbacks are far from being independent of one another and their intensities are intermingled (Stephens, 2005; Klein & Hall, 2015). Thus some of the issues raised by WCRP and that deal with circulation / cloud / climate relations require the use of satellite observations and the synergy of existing instruments and of their long series of observations. We aim to improve our understanding of the cross-relationships between clouds and their environment by means of satellite observations, combining passive and active remote sensors. The project will be integrated into two laboratories of the Institut Pierre Simon Laplace, namely LATMOS <www.latmos.ipsl.fr> and LMD <www.lmd.jussieu.fr>. These two labs are strongly involved into the analysis of CloudSat/Calipso/Megha-Tropiques satellite missions and in the up-coming EarthCare ESA/JAXA satellite. Applicants should have obtained a degree (M.Sc. or equivalent) in science, mathematics or engineering and should be fluent in english. The candidates should have a background in atmospheric sciences and climatology. Some expertise in computer sciences would be beneficial. The PhD position is for 3 years, starting on October 1st, 2017. Applicants should send (i) a statement of interest, (ii) a complete CV as well as (iii) copies of transcript of records of your MSc and (iv) contact information for two references via email to Dr Hélène Brogniez <email@example.com> and to Pr Hélène Chepfer <firstname.lastname@example.org>. Helene Brogniez (email@example.com) Enseignant-Chercheur (HdR) / Associate Professor Laboratoire "ATmospheres, Milieux, Observations Spatiales" (LATMOS) UVSQ-CNRS-IPSL, 11 bvd d'Alembert, 78280 Guyancourt, FRANCE
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