Historical reconstructions of steric sea levels
Steric sea level changes are the changes in sea level associated with temperature and salinity changes causing seawater to expand or contact as its density changes. At present day, three techniques are available to reconstruct steric sea level changes, based on (i) the statistical analysis of in situ temperature and salinity measurements (objective analysis); (ii) the combination of ocean general circulation models with observations of the ocean state (ocean reanalysis) and (iii) the combination of satellite radar altimetry and time-lapse gravimetry measurements (satellite geodesy). I compared the historical reconstructions from two objective analyses (EN4 and CORA5), one ocean reanalysis (ORAS4) and one combination of satellite geodetic data (CMEMS - GSFC) to extract robust features associated with the ocean natural variability at interannual to multidecadal time scales. The analysis of such datasets is available on the ANU sea level website (http://sealevel.anu.edu.au). This includes the total steric signals computed from four different datasets, the annual climatology, the signal asociated with climate modes (including climate mode fingerprints) and the residual signals, mostly associated with ocean circulation (Gulf Stream, Kurushio, Agulhas etc.).
Documentation:
Please cite our paper, if you find these results useful:
Pfeffer, J., Tregoning, P., Purcell, A. and Sambridge, M. (2018). Multitechnique Assessment of the Interannual to Multidecadal Variability in Steric Sea Levels: A Comparative Analysis of Climate Mode Fingerprints. Journal of Climate, 31, 7583-7597. https://doi.org/10.1175/JCLI-D-17-0679.1
Please cite our paper, if you find these results useful:
Pfeffer, J., Tregoning, P., Purcell, A. and Sambridge, M. (2018). Multitechnique Assessment of the Interannual to Multidecadal Variability in Steric Sea Levels: A Comparative Analysis of Climate Mode Fingerprints. Journal of Climate, 31, 7583-7597. https://doi.org/10.1175/JCLI-D-17-0679.1
AusPass: the Australian Passive Seismic Server
Since February 2018, I work at part time for the seismology group at the Research School of Earth Sciences in Canberra, Australia. The objective of the AusPass project is to distribute the passive seismological data acquired in Australia since the 1980s. I am the web developer of the team and created the whole AusPass website (http://auspass.edu.au/). I also contribute to the seismic data management (processing and formatting) and will soon go on the field to deploy new seismic arrays in Central Australia.
The data from the following arrays are now available in AusPass:
The data from the following arrays are now available in AusPass:
- BILBY: North-South array across central Australia
- AUSIS: Australian Seismometers in Schools (nationwide)
- SKIPPY: nationwide array named after the famous bush kangaroo and designed to image the Earth's structure in 3D beneath Australia
- KIMBA: pair of arrays deployed in 1997 and 1998 in the Kimberley Region
- SOC: arrays deployed in 2007 and 2008 in South Australia
- WACRATON: arrays deployed in 2000 - 2001 across West Australian cratons
- CAPRAL: arrays deployed in 2005 - 2007 in Western Australia
- BASS: arrays deployed in 2011 - 2013 from Southern Victoria to Northern Tasmania to image the lithosphere beneath the Bass strait
The ALTIGAPS database
Content:
ALTIGAPS stands for ALtimetry, TIde GAuges and gPS. As the name implies, it is a global synthesis of multisatellite altimetry, tide gauge and GPS measurements acquired in coastal areas over the 20 past years. The data are processed to extract 20-years trends and their uncertainties in:
You will find here the ALTIGAPS database in ASCII format, and here formated as a shapefile for GIS users.
Application:
ALTIGAPS offers the opportunity to look independently into the recent dynamic processes affecting the ocean and the interior of the Earth. Recent climatic processes responsible for the sea level changes can be studied independently of the subsidence or uplift of the coast. Besides, new constraints are brought on the vertical deformation of the coastal continental platforms due to various geodynamical processes. But, above all, ALTIGAPS constitutes a powerful tool to evaluate, understand and predict the natural hazards associated with changing sea levels in coastal areas.
Documentation:
Please cite our paper, if you find these results useful:
Pfeffer J. and P. Allemand, 2016, The key role of vertical land motions in coastal sea level variations: a global synthesis of multisatellite altimetry, tide gauge data and GPS measurements, Earth Planet. Sc. Lett., 439, 39-47, doi:10.1016/j.epsl.2016.01.027.
ALTIGAPS stands for ALtimetry, TIde GAuges and gPS. As the name implies, it is a global synthesis of multisatellite altimetry, tide gauge and GPS measurements acquired in coastal areas over the 20 past years. The data are processed to extract 20-years trends and their uncertainties in:
- Relative sea level changes (RSL): they are the changes in sea level with respect to the coast. They correspond to the sea level changes “felt” by coastal populations. They are measured at tide gauges and evaluated at GPS stations as the difference between altimetry and GPS measurements.
- Absolute sea level changes (ASL): they are the changes in sea level with respect to the center of mass of the Earth. They are measured by multisatellite radar altimetry over all the oceans except at very high latitudes. They are validated at tide gauges by the difference of tide gauge and GPS measurements.
- Vertical land motions (VLM): they are the vertical displacement of the coast itself observed with respect to the center of mass of the Earth. They are directly measured at (semi-)permanent GPS stations and can also be calculated as the difference between altimetry and tide gauge measurements.
You will find here the ALTIGAPS database in ASCII format, and here formated as a shapefile for GIS users.
Application:
ALTIGAPS offers the opportunity to look independently into the recent dynamic processes affecting the ocean and the interior of the Earth. Recent climatic processes responsible for the sea level changes can be studied independently of the subsidence or uplift of the coast. Besides, new constraints are brought on the vertical deformation of the coastal continental platforms due to various geodynamical processes. But, above all, ALTIGAPS constitutes a powerful tool to evaluate, understand and predict the natural hazards associated with changing sea levels in coastal areas.
Documentation:
Please cite our paper, if you find these results useful:
Pfeffer J. and P. Allemand, 2016, The key role of vertical land motions in coastal sea level variations: a global synthesis of multisatellite altimetry, tide gauge data and GPS measurements, Earth Planet. Sc. Lett., 439, 39-47, doi:10.1016/j.epsl.2016.01.027.
Low-water maps of the groundwater table in central Amazon
Content:
We provide here the first regional maps of the groundwater table in the central Amazon. The maps show the height of the aquifer during low water periods from 2003 to 2008. They are based on the minimum surface water levels derived from spatial altimetry over more than 500 rivers, lakes, and floodplains.
Find here the groundwater maps and here the minimum surface water levels derived from altimetry.
Application:
Our maps provide critical information about the spatial and temporal patterns of the groundwater table across the central Amazon region. They can be used to better represent groundwater in hydrological models and better understand hydrological processes at large scales. One should however keep in mind that the maps are only valid at regional scale, during low-water periods, in the alluvial plain of the central Amazon and for areas reasonably covered by virtual altimetry stations.
Documentation:
Please cite our paper, if you find these results usefull:
Pfeffer, J., F. Seyler, M.-P. Bonnet, S. Calmant, F. Frappart, F. Papa, R. C. D. Paiva, F. Satgé, and J. S. D. Silva (2014), Low-water maps of the groundwater table in the central Amazon by satellite altimetry, Geophys. Res. Lett., 41, 1981–1987, doi:10.1002/2013GL059134.
We provide here the first regional maps of the groundwater table in the central Amazon. The maps show the height of the aquifer during low water periods from 2003 to 2008. They are based on the minimum surface water levels derived from spatial altimetry over more than 500 rivers, lakes, and floodplains.
Find here the groundwater maps and here the minimum surface water levels derived from altimetry.
Application:
Our maps provide critical information about the spatial and temporal patterns of the groundwater table across the central Amazon region. They can be used to better represent groundwater in hydrological models and better understand hydrological processes at large scales. One should however keep in mind that the maps are only valid at regional scale, during low-water periods, in the alluvial plain of the central Amazon and for areas reasonably covered by virtual altimetry stations.
Documentation:
Please cite our paper, if you find these results usefull:
Pfeffer, J., F. Seyler, M.-P. Bonnet, S. Calmant, F. Frappart, F. Papa, R. C. D. Paiva, F. Satgé, and J. S. D. Silva (2014), Low-water maps of the groundwater table in the central Amazon by satellite altimetry, Geophys. Res. Lett., 41, 1981–1987, doi:10.1002/2013GL059134.