PhD studentship on cosmic rays, clouds and climate
Fully funded Marie Curie ITN studentship
Degree in Physics, Chemistry or mathematical sciences ideal.
This PhD is offered through an EU “Initial Training Network” (ITN), which is a funded collaboration of 10 European institutions.
Scientific objectives
The aim of the CLOUD-ITN project is to investigate the influence of galactic cosmic rays (GCRs) on ions, aerosols, cloud condensation nuclei (CCN) and clouds using the research facility at CERN (Geneva), and thereby to assess the significance of a possible "solar indirect" contribution to climate change. The research at Leeds concerns numerical modelling of the effects of cosmic rays on ions, aerosol and clouds, using new results from the field and laboratory experiments. The collaborative nature of the project means that all students are expected to participate in aspects of the field and laboratory experiments.The IPCC estimates that changes of solar irradiance (“direct solar forcing”) have made only a small (7%) contribution to the observed warming. However, uncertainties remain on other solar-related contributions, such as the effects of changes of ultra violet radiation or galactic cosmic rays on aerosols and clouds.
In its Fourth Assessment Report (June 2007), the IPCC states: “Whether solar wind fluctuations […] or solar-induced heliospheric modulation of galactic cosmic rays […] also contribute indirect forcings remains ambiguous” and, ”...quantitative estimates of galactic cosmic ray-induced changes in aerosol and cloud formation have not been reached.” The IPCC concludes on radiative forcings due to cosmic rays: “Certainties: Some empirical evidence and some observations as well as microphysical models suggest link to clouds. Uncertainties: General lack/doubt regarding physical mechanism; dependence on correlation studies. Level of scientific understanding: Very low”
A review of the science, written by three of the project partners is available:
Carslaw, K.S.; Harrison R.G.; Kirkby J. (2002) Cosmic rays, clouds and climate, Science, 298, pp.1732–1737. doi:10.1126/science.1076964
This project aims to settle these important unanswered questions of the IPCC on possible cosmic ray effects on clouds and climate.
The project was scientifically approved by the CERN Research Board in March 2006. It aims at conducting experiments in an aerosol chamber facility which will be exposed to an elementary particle beam at CERN, allowing the effects of cosmic rays on atmospheric aerosol and cloud formation to be realistically simulated. A first prototype CLOUD aerosol chamber was successfully operated in the beam at CERN in fall 2006, and more advanced aerosol chambers will be operated at CERN in fall 2008 and in the subsequent years.
The collaboration
The CLOUD-ITN participants represent a strong interdisciplinary team of atmospheric, cosmic ray and particle physicists, reflecting the nature of this research which lies at the intersection of several disciplines. The 10 Network Partners are: Leeds, Reading, Frankfurt, CERN (Switzerland), Paul Scherrer Institute (Switzerland), Helsinki, Institute for Tropospheric Research (Germany), Max Planck Institute for Nuclear Physics (Germany), Ionicon (GmbH Austria), Vienna (Austria).The work is divided into 10 inter-linked research projects. The projects are centred around two sets of experiments at CERN, where the influence of cosmic rays on aerosol formation is studied in an aerosol chamber. The projects progress from fundamental laboratory measurements, through new mechanistic models of ion-aerosol processes to implementation in a global climate model. Each project covers either one PhD thesis for an early stage researcher (ESR) or a project for an experienced researcher (ER; postdoctoral researcher). Each research project is an essential part of the overall effort and contributes to the expected key scientific achievements (see B 2.4). The research is complemented by a set of secondments to partner institutions to enlarge the knowledge and the experimental/modelling experience of the researchers.
All PhD students will participate in dedicated summer and winter schools, collaboration meetings, exchanges and secondments to partner institutions.