ORGANISATION/COMPANYTallinn University of Technology
RESEARCH FIELDEngineering › OtherGeosciences › Other
RESEARCHER PROFILEFirst Stage Researcher (R1)
APPLICATION DEADLINE21/06/2019 23:00 - Europe/Athens
LOCATIONEstonia › Tallinn
TYPE OF CONTRACTTemporary
HOURS PER WEEK40
Geodetic observing systems such as continuously operating GNSS reference stations are utilised in many navigation, mapping, engineering and research applications. In particular, the GNSS based height determination in conjunction with a precise geoid model (represents the mean sea level) is widely appreciated. High demand for accurate geodetic products has contributed to the geodetic infrastructure being well developed on land. However, the specifics of the marine areas and the needs of offshore industry have not been fully considered, yet. For instance, over the land the typical accuracy of contemporary geoid models is 1-3 cm, whereas the anticipated accuracy of marine geoid models is considerably lower (not exactly known over many marine areas). Insufficient accuracy and poor spatial resolution of the marine geoid models are major deficiencies in the utilisation of some of the most advanced technologies presently available.
Accordingly, the emphasis of the study is on elaborating marine geoid modelling methods. These methods need to be complemented/adapted to reach the main goal - Development of an iterative approach for improvement Marine Geoid modelling. It should be noted that usually the geoid model is expected to assist in determining the sea surface height (SSH) anomalies, but instead now we reversely use our existing knowledge on known persistent dynamic topography (DT) anomalies to assist in improving the marine geoid. Thus the geoid modelling becomes an iterative process.
The study needs to be complemented with high-precise geometrical observations. SSH either can be observed with satellites over the oceans or with tide gauges at the coasts. Over the open oceans, satellite altimetry (SA) is the main information source providing the absolute sea level at a specific location and at a specific time with respect to a geometric reference frame. Unfortunately, SA is not capable to observe the geometric sea surface height at the coastal zone with sufficient accuracy and to use this information to connect the tide gauge stations overseas. In order to analyse all marine observations (e.g. combining SA and tide gauge records) they need to be available in a common reference frame. Regional sea level research is thus closely linked to height system unification of participating countries and needs to be solved jointly.
For the determination of ellipsoidal/geometric 3D-coordinates of near tide gauge ground points the concept of geodetic synthetic aperture radar (SAR) is a promising new technique. Under optimal conditions and with dedicated corner reflectors 3D geometric positions with centimeter accuracy could be determined. One of the critical issues is long term vertical land uplift/subsidence due to Glacial Isostatic Adjustment (GIA), the impact of which need to be included to the sea level records. Geodetic SAR can be used for connect all tide gauges overseas to the regional geometric network, which is needed to extricate the vertical land motion from the tide gauge readings and provide constraints for marine geoid modelling.
The PhD candidate shall develop and validate a methodology that improves the resolution and accuracy of geoid in marine areas by utilising various geoid methodology approaches and also a synergy of various in situ, marine and satellite data sources.
- The candidate shall examine and elaborate further contemporary geoid modelling methods specifically adapted for marine areas.
- Combination of different data sources that includes: satellite altimetry, hydrodynamic models, tide gauges, airborne laser scanner, geodetic SAR and GNSS; shall be employed. Utilization of these different techniques allows to obtain increased resolution offshore. The utilization of data assimilation techniques (e.g a Bayesian statistical approach) play a key component in improvement in the marine geoid modelling.
- Control data are to be used for constraining the marine geoid models.
- The results are to be verified against the other geoid modelling methods.
- The geodetic SAR technique to be applied for connecting regional tide gauge stations into unified height system.
- Impact of the vertical land motion to the sea level series needs also to be accounted for.
- The candidate is expected to assist in project related field campaigns.
This study is part of the Estonian Research Council supported research for developing an iterative approach for near-coast marine geoid modelling by using re-tracked satellite altimetry, in-situ and modelled data.
- The PhD candidate is expected to be at full time position for a duration of 4 years.
- Tuition fee is waived for all PhD students.
- All PhD students studying with full-load have the right to receive doctoral allowance (660 €) paid by the government. The research group provides the remaining salary.
- The candidate is obligated to participate and fulfil the requirements of Tallinn University of Technology PhD programme.
- Additional funds will be provided (and whence applicable the associated funding can be applied for) for research trainings, conferences and international mobility/stays abroad with durations of up to 6 months.
For inquiries regarding the position and more information consult the project website http://gece.ttu.ee/~geoid/ and e-mail addresses therein.
REQUIRED EDUCATION LEVELGeosciences: Master Degree or equivalentOther: Master Degree or equivalent
The applicants should fulfill the following requirements:
- University degree (M.Sc.) in geodesy or geomatics.
- Consideration will also be given to applicants whose previous degrees are in appropriate related disciplines, such as Earth Sciences, Mathematics, Physics or Software Engineering.
- Skills in data analysis, mathematics and statistical analyses (to be trained).
- Ability for independent research as part of a team, interest in the presentation and publication of scientific results.
- Advanced computer literacy and programming skills.
- Good command of the English language (speaking and writing).
- Motivation letter
- Curriculum vitae
- Copy of the required diploma (MA) or other document providing evidence of the necessary qualification.
EURAXESS offer ID: 399232
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