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Paul Tregoning: Environmental Geodesy

Paul Tregoning: Environmental Geodesy

Geodesy-related Student Projects

Variations in water resources in regional drainage basins


GRACE satellites in orbit around the Earth (Courtesy NASA/JPL-Caltech)
The Gravity Recovery and Climate Experiment (GRACE) space gravity mission now provides the capability to measure temporal mass variations of the Earth at sub-continental scales. Thus, it is now possible to estimate water resources at drainage-basin scales.

Studies of temporal variations in water of the Murray-Darling and other large-scale drainage basins are underway. Linking such large-scale information with hydrologic data provides a powerful monitoring capability for Australia's water resources.

Publications

Leblanc, M., P. Tregoning,, G. Ramillien, S. Tweed, A. Fakes, 2009. Basin scale, integrated observations of the early 21st Century multi-year drought in southeast Australia, Water Resources Res., 45, W04408, doi:10.1029/2008WR007333. (pdf)



Quantifying sea level change


Satellite altimetry measures global sea level (Courtesy NASA/JPL-Caltech)
Sea levels change as a result of thermal expansion of the oceans under a warming climate but also through the exchange of water between the oceans and the continents/atmosphere. An increase in snow accumulation requires a reduction in ocean volume, whereas melting of continental ice causes an increase in ocean volume; therefore an increase in sea level.

Satellite altimetry is used to measure sea surface heights, from which sea level variations can be deduced. Improvements to the geodetic reference frame, orbit estimation of altimeter satellites and calibration/validation of altimeters are required in order to estimate accurate rates of sea level variations.



Modelling atmospheric effects


Mean improvement in height estimate produced by using accurate surface pressure when analysing GPS data
The propagation of radio signals through the Earth's atmosphere is still the most limiting factor in determining accurate height estimates from GPS and VLBI analyses. Recent advances in developing time-varying mapping functions (such as the VMF1 developed by Johannes Boehm in Vienna) and the use of more accurate a priori hydrostatic delays have made significant improvements.

Future research in this area includes modelling asymmetric variations in the atmosphere, variations in atmospheric pressure tides, improved atmospheric pressure loading models and improved modelling of the a priori atmospheric delays.

Selected relevant publications

Tregoning, P. and C. Watson, Atmospheric effects and spurious signals in GPS analyses, J. Geophys. Res., , in press
pdf

Boehm, J., P.J. Mendes Cerveira, H. Schuh, P. Tregoning, 2007. The impact of mapping functions for the neutral atmosphere based on numerical weather models in GPS data analysis, IAG Symopsium Series, P. Tregoning and C. Rizos (Eds), 130, 837-843.
pdf

Tregoning, P. and T. A. Herring, 2006. Impact of a priori zenith hydrostatic delay errors on GPS estimates of station heights and zenith total delays, Geophys. Res. Lett., 33, doi:10.1029/2006GL027706.
pdf

Boehm, J., A. E. Niell, P. Tregoning, H. Schuh, 2006. The GMF: A new empirical mapping function based on numerical weather model data, Geophys. Res. Lett., 33(7), doi:10.1029/2005GL025546.
pdf

 


Student Research Projects @ RSES

In the Drop down menus below choose the Degree type you are looking to complete then a subject type and if you know of a supervisor
you wish to study under select the supervisors name then click on the search button and the relevant projects will be displayed.
If you do not make any selections all available projects will be displayed.

Degree Type ? Subject?Supervisor?
Note: These projects are an indication of the topics available, you should contact your prospective supervisor asap to discuss the details of the project.
Mass variations estimated from GRACE
project image
Supervisor:Tregoning, Paul
Subject keywords: Geodesy/GPS, Mathematical Geophysics, Physics, Geophysics, Computational
Degree types: Honours, M.Sc, PhD, PhB,
The Gravity Recovery and Climate Experiment (GRACE) space gravity mission provides a means of estimating changes in mass on the Earth, including hydrological processes, oceanic variations and melting of polar ice sheets. The raw measurements are actually changes in the distance (accurate to 1/10 of the width of a human hair) between two satellites orbiting at 450 km altitude and separated by ~200 km. To achieve this, we must first compute the orbit of the two satellites, taking into account gravitational effects of the Sun, Moon, ocean tides, atmospheric variations to then be able to identify the signal of the temporal changes in the Earth's gravity field. The figure shows the accumulation of mass( i.e. water) on the east coast of Australia during the 2011 January floods as estimated by GRACE.

The student will be involved in developing software and background models to derive more accurate estimates of the Earth's gravity field. They will then use the estimates to study geophysical processes on Earth.

Monitoring groundwater changes in Australia
project image
Supervisor:Tregoning, Paul
Subject keywords: Sea level change/Climate change, Geodesy/GPS, Mathematical Geophysics, Geophysics, Computational GRC
Degree types: Honours, M.Sc, PhB
Water is a critical resource for Australia. We can't begin to manage properly what we don't monitor; therefore, monitoring the changes in water resources at local- and basin-scales is becoming increasingly important. The Gravity Recovery and Climate Experiment (GRACE) satellite gravity mission enables the possibility to measure basin-scale mass changes at monthly intervals, yet such capability is not being exploited to monitor Australia\'s water systems. Considerable research is required to determine the accuracy of the technique in the Australian environment where drainage basins are relatively small. This would involve the analysis and comparison of different international GRACE solutions and simulations for the Australian region to assess the achievable accuracy. The student would conduct an interesting scientific study that should lead to unique results pertinent to water resources in the Australian region.
Climate Change and the Melting of Polar Ice Caps
project image
Supervisor:Tregoning, Paul
Subject keywords: Geodesy/GPS,Sea level change/Climate change,Mathematical Geophysics,Physics,Computational,Fieldwork, GRC,
Degree types: PhD,
Global warming is causing increased melting in polar regions. How do we know this? Because we can measure changes in mass balance (or the amount of ice that has melted) using space-geodetic techniques that detect variations in the Earth's gravity field and changes in ice height.
How fast are Antarctica and Greenland melting and how is such melting contributing to rising sea level?
There is the opportunity to study all aspects of the effects and ramifications of climate change, from measuring sea level variations using satellite altimetry and tide gauges, measuring with GPS the rebound of the Earth's crust caused by the melting of past ice sheets, monitoring mass balance changes through GRACE observations of gravity changes and/or assimilating all these observations to develop new models of past and present ice sheets for Greenland, Antarctica and North America. This exciting area of research has direct implications for understanding the present-day effects of climate change.
Sensing water vapour in the atmosphere using GPS
project image
Supervisor:Tregoning, Paul
Subject keywords: Geodesy/GPS,Sea level change/Climate change,Climate Dynamics,Physics,Geophysics,Computational,Analytical,
Degree types: Honours,M.Sc,PhD,PhB,
Signals transmitted from satellites orbiting the Earth are delayed as they pass through the troposphere of the Earth. This is measurable by GPS and so it is possible to measure how much water vapour is actually in the atmosphere using GPS. This is a new area of research that will involve the student learning about high-accuracy GPS analysis and modelling of the atmospheric effects. The map to the right shows the precipitable water vapour over the USA as estimated from GPS observations. Assimilating this information into weather forecasting and climate studies has not yet been attempted in Australia.

Contact the supervisor directly for more information.

Combining Very Long Baseline Interferometry and GPS in Australia
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Supervisor:Tregoning, Paul
Subject keywords: Geodesy/GPS,Mathematical Geophysics,Physics,Computational,Fieldwork,GRC,
Degree types: PhD,
Very Long Baseline Interferometry (VLBI) involves observing radio sources with astronomy telescopes, from which very accurate estimates of distances between telescopes and estimates of Earth rotation can be made. Recently, a software program was developed at Swinburne University (Victoria) to correlate astronomic VLBI observations - which is a very significant improvement over convential correlation and provides Australian researchers with considerable independence. This PhD program will involve continuing the development of the software correlator so that it can be applied to geodetic VLBI observations as well. Once this can be done, exciting new opportunities will become available - such as observing GPS satellites using VLBI instruments, analysing for the first time the data from the new VLBI installations in Western Australia and the Northern Territory (to be commissioned in 2008). The student will be involved in developing and enhancing software, analysing VLBI data and integrating the VLBI observations to GPS satellites into existing geodetic software packages. The student will be supervised jointly by Steven Tingay (Swinburn) and Paul Tregoning (ANU).

We don't know yet what new results such research is going to uncover ...... come and find out!

Tectonic deformation of Papua New Guinea
project image
Supervisor:Tregoning, Paul
Subject keywords: Geodesy/GPS,Tectonics/Earth Deformation/faults,Mathematical Geophysics,Geophysics,Computational,Analytical,Fieldwork,
Degree types: Honours,M.Sc,PhD,PhB,
Papua New Guinea is one of the most active tectonic regions of the world, with every possible type of plate boundary, dozens of active faults and several major earthquakes occurring every year. Measurement of ground movement from GPS observationscan tell us about deformation, strain caused by locked faults etc. Estimating earthquake locations can identify faults and explain the observed deformations. There are numerous research projects available using earthquakes and/or geodetic data to study how the Earth moves in Papua New Guinea.

Contact the supervisor directly for more information.