Palaeoceanography and Climate Visualisation Models
The Lambeck European Ice Sheet and Shoreline 3D Visualisation Model
Throughout the Earth's history our climate has varied dramatically resulting in fluctuations in global temperature, rainfall, sea-level and ice coverage. The most dramatic changes in the recent past have been the ice ages; periods of lower temperatures occurring around every 100,000 years where polar ice extends into the middle latitudes. Understanding these processes and how they interact to produce our climate is essential if we are to be able to predict and adapt to future changes.
During the Last Glacial Maximum (LGM), 22,000 years ago, global sea-levels were 130m lower than the present day due to the transfer of water from the oceans to the ice sheets and associated thermal effects. Sea-level changes since the LGM are complicated by the fact that the ice itself depresses the crust due to its weight upon the Earth's surface. Sea-level at any point on the Earth's surface is therefore controlled by the amount and temperature of water in the oceans (eustasy) and the loading and unloading of the Earth's crust by the expansion and contraction of ice sheets (isostasy). This complex interaction determines relative sea-level change (RSL) - the change in the elevation of the sea surface with the solid Earth at any location.
Detailed time-slice reconstructions showing the
evolution of north-west Europe have been derived for the period since
the LGM (Lambeck 1995, 1996), based on glacial isostatic adjustment
(GIA) modelling. The model takes the observed geological data and
combines this information with geophysical modelling which incorporates
a numerical description of the rheology of the Earth's crust and upper
mantle. It derives and outputs a data set which has calculated grid
values by extrapolating between known data points. These
reconstructions show the distribution of ice and the position of the
coastline as it evolved in response to both eustatic and isostatic
change.
This data has been incorporated into an interactive 3D visualisation package allowing real time manipulation and animation of the Lambeck output, via simple mouse and keyboard interactions. This allows a user to move amongst past climates, change the time steps at will and to interact with the data via colour shading, sea-level manipulation and a host of other features. You are encouraged to freely download this software and use it for your own interest, education or research. The software itself and further details on how to use this visualisation including what it tells us are found within the zip file below.
Download the Lambeck visualisation model
Download this link: EarthSeaTrilogy.zip by right clicking on it and choosing the 'save link (or target) as' option. Once downloaded to your computer unzip the file and follow the 'readme.txt' file found within the folder to run the software. Further help and background information files are then found inside the application. The software runs using Java and Java3D technologies. These are also free and installation instructions are also found within the readme file.
The European Palaeotidal Visualisation Model
The European Palaeotidal Visualisation Model uses the coastline position as determined by Lambeck (Lambeck, 1995) as a basis for reconstructing the hydrographic evolution of the European shelf seas since the LGM (Uehara et al. 2006).
The model (based on the Princeton Ocean Model) uses present day bathymetry as determined from a number of sources such as: the Proudman Oceanographic Laboratory, the British Geological Survey and the US National Data Centre, takes the palaeoshoreline parameters as determined by Lambeck and uses these to predict:
- Tidal amplitudes
- Tidal currents
- Mean high water spring tide
- Tidal mixing fronts (Simpson / Hunter parameter)
- Peak bed stress vectors (Uehara et al. 2006)
The palaeotidal model runs with the same resolution and time steps as the original Lambeck model (i.e. 1/12 degree of latitude and longitude from 15W - 15E and 45N - 65N, back to the LGM in thousand year time steps). As with the Lambeck visualisation the software is fully interactive, allowing the user to manipulate, animate and view the data using simple mouse and keyboard interactions. The software has been developed using Java and is therefore platform independant. This model is of interest as it is the first shelf-wide palaeotidal model which can:
- Incorporate dynamic earth crust information from GIA output. This is important as vertical movements of the crust through time determine how coastlines and bathymetries evolve
- Reconstruct seasonal stratification dynamics, with profound implications for the role of shelf seas in the carbon cycle (Rippeth et al. 2007)
- Determine sediment dynamics. As such this model can be used as a predictive tool for determining offshore aggregate resources, and will help in predicting sedimentation and erosional responses to engineered changes in the shelf environment (such as wind farm construction). These predictions also form a basis for understanding the evolution of shallow marine habitats through time.
Download the European Palaeotidal Model
Download this link: EuropeanTidalModel.zip by right clicking on it and choosing the 'save link (or target) as' option. Once downloaded to your computer unzip the file and follow the 'readme.txt' file found within the folder to run the software. Further help and background information files are then found inside the application. The software runs using Java technology. This is also free and installation instructions are found within the readme file.
This project has received funding from the research collaboration between Aberystwyth and Bangor Universities under the Catchment to Coast programme.
References:
- Lambeck K., 1995, Late Devensian and Holocene shorelines of the British Isles and North Sea from models of glacio-hydro-isostatic rebound. Journal of the Geological Society, 152, 437-448
- Lambeck K., 1996, Glaciation and sea-level change for Ireland and the Irish Sea since Late Devensian / Midlandian time. Journal of the Geological Society, 153, 853-872
- Uehara K., Scourse J. D., Horsburgh K. J., Lambeck K., Purcell A. P., 2006, Tidal Evolution of the northwest European shelf seas from the Last Glacial Maximum to the present. Journal of Geophysical Research-Oceans, 111 (C9) C09025
- Rippeth T., Scourse J.D., Uehara K., McKeown S., 2007, The influence of sea-level rise on atmospheric CO2 concentrations over the last deglacial transition. Nature, in review
Contact Information:
For more information on these projects please contact: A. Wainwright1, T. Varsamidis2, J. Scourse1, or K. Uehara31 School of Ocean Sciences, University of Wales, Bangor, UK
2 School of Computer Science, University of Wales, Bangor, UK
3 Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka, Japan