Beasiswa PhD Utrecht University                                         

The departments of Earth Sciences and Environmental Sciences are currently looking for 2 PhD students (AIO) (f/m) for the High Potential Programme granted by the Utrecht University: Global Change and Hurricanes. The research of the departments is part of the Copernicus Institute for Sustainable Development and Innovation and of the Organic Geochemistry group from the department of Earth Sciences.

Project description: Global Change and Hurricanes:
If and how global warming affects hurricane activity is a topic of considerable interest and intensive research efforts. The available instrumental record, however, is still too short to document and understand the complex links within the climate system responsible for hurricanes. Only through extending the records beyond the instrumental measurements by paleodata, we can capture the full range of natural variability inherent to the climate system. This allows quantification of the separate effects of changing environmental variables. We aim to construct detailed paleo-records from Florida and the Gulf of Mexico for the past 10.000 years which trace back the conditions within the natural system that trigger intensive hurricane seasons. For the first time, paleo-records of precipitation, vegetation, storm induced runoff and sea surface temperatures will be combined in a modeling environment. Only long-term records integrated by modelling the ocean-atmosphere biosphere system enable the detection of any deviations from the normal state that may consequently be ascribed to ongoing and future human interference with the system.

Paleoecologists and Earth-scientists from the Utrecht University will produce detailed marine and terrestrial proxy data of sea surface temperature (SST), precipitation, CO2, BIT index (influx of organic matter in marine sediments), d18O and vegetation patterns. Environmental scientist will integrate these records through numerical process modelling.
PhD student 1: Sea Surface Temperature and storm detection in the marine realm
Accurate correlation of marine and terrestrial settings is of prime importance for time equivalent documentation of environmental changes and to evaluate the synchronicity of occurring shifts and events. Stable hydrogen isotopes, measured directly on both, leaf fragments from terrestrial sites and from biomarker molecules in marine settings, will be used to establish a robust correlation of the contrasting realms. With the accurate dating of the different sites, we will be able to provide a well-defined timeframe for phases characterized by increased storm activity, allowing the systematic analysis of periodicities and amplitude changes of the natural system. Sea surface temperature will be reconstructed using both well established and newly developed organic geochemical proxies (UK37, TEX86). Major hurricane landfalls induced storm surges will be investigated by looking at their distinct imprints in the sedimentology of the coastal and on-shore environments.

Hurricanes in the wider surroundings of the studied transect will be reconstructed from marine sediments, using state of the art organic geochemical techniques. The stable oxygen and hydrogen isotopic signatures of respectively cellulose and leaf waxes will be used to quantify past changes in the strong convection and thus isotopic fractionation caused by hurricane-tied precipitation.

Combining stable hydrogen and oxygen isotopes in fossil plant organic matter (leaf, wood and biomarker molecules) thus allows detailed reconstruction of past hurricane intensity. The PhD student will be involved in both field work and organic geochemical analyses.

PhD student 2: Ocean-Atmosphere-Biosphere interactions
The paleo-records can be integrated in different models acting on various levels of the coupled ocean-atmosphere-biosphere system. These paleo time-series can be used to directly link increased hurricane intensity, which is reflected by SST and BIT, with the dynamics of vegetation and catastrophic runoff amounts caused by hurricanes. However, several feedback mechanisms between the atmosphere and biosphere need to be included to understand potential nonlinearities between ocean-atmosphere-biosphere systems since they may cause sudden shifts in precipitation, evapo-transpiration/runoff ratios and vegetation. Therefore numerical dynamical models on regional scale need to be used and developed. Inverse modeling, with the paleo-records derived from contrasting environments and based on contrasting biogeochemical and paleobotanical techniques allows us to test the accuracy and information value of the different proxy-data sets.

The PhD student will work together with earth scientists and paleo-ecologists from Utrecht University, who also take part in the High Potential Programme, and with several institutes in Florida. Main task of the candidate is modelling although the candidate will also be involved in field work and lab analyses. The project will lead to a PhD thesis.

Qualifications for PhD position 1:
Highly motivated candidate with experience in Earth Sciences and a MSc in an appropriate field.

Qualifications for PhD position 2:
The candidate must have experience in modelling and programming of dynamical climate models and holds a MSc (or equivalent) degree in a relevant field (e.g. earth sciences, environmental sciences, meteorology).

Terms of employment
We offer a fulltime PhD position for 4 years (0.8 fte is an option). The gross monthly salary increases from EUR 1,956.- in year 1 to EUR 2,502.- in year 4, according to the Collective Employment Agreement of the Dutch Universities. Secondary benefits include e.g. a pension scheme, flexible employment conditions, holiday bonus and end-of-year bonus.

Further details
Are you interested? You can obtain further details for PhD1 from Dr. Gert-Jan Reichart (phone: +31(0)30 253 5041 e-mail: g.reichart@geo.uu.nl  or Prof. Dr.ir. J.S. Sinninghe Damsté (phone: +31(0) 222 369550 e-mail: damste@nioz.nl

For PhD2: Dr. Stefan C. Dekker (phone +31(0)30 253 2500 e-mail: s.dekker@geo.uu.nl or Prof. Dr. Martin J. Wassen (phone: +31(0)30 253 5764, e-mail: m.wassen@geo.uu.nl

You may also visit the groups website at: www.geo.uu.nl/ivau  and www.geo.uu.nl/environmentalsciences

Application
Applications, including a curriculum vitae, a statement of your research interests, and the names and addresses of 2 references, must be sent to:

Faculty of Geosciences - Personnel Department
PO Box 80115
3508 TC Utrecht, The Netherlands

or submitted by e-mail to: peno@geo.uu.nl

Please mention where you originally saw our advertisement and quote vacancy number 72077 in all communications. The positions are open until May 31, 2007.