Royal Netherlands Institute for Sea Research
Royal Netherlands
Institute for Sea Research

Present-day sea-level change along the coast of Brazil

Sea-level change is not a spatially uniform process. On the contrary, regional differences from the global mean sea-level change (~3 mm/yr from 1993-2017), can be large, reaching up to 15 mm/yr depending on the study region. Thus, understanding sea-level change regionally is critical for adaptation policies.

Contrasting with the high number of studies focusing on European and North-American sea-level change, sea-level change at the coast of Brazil has been poorly investigated over the last decades. One of the reasons is the lack of data available in the region. Along the 7491 km of the Brazilian coast, there are only 12 tide gauges registered at the Permanent Service for Mean Sea Level (PSMSL), of which only two have been updated in the last 3 years. In face of this issue, several Brazilian universities set up SIMCosta1, a project that aims to improving coastal monitoring using oceanographic buoys and tide gauges. Currently, the project has installed 7 tide gauges (Figure 1), from which the data is freely available at the project website.

While these tide gauge time series are too short to describe the long term present-day sea-level change at the coast of Brazil (most of the records now cover 2 years), the satellite altimetry record (since 1993) is long enough to be used in such studies. However, sea-levels from satellite altimetry may be contaminated by the presence of land in the near-shore region, and thus are limited to 20-50km from the coast. Furthermore, the coastal ocean has a more complex dynamic than the open ocean, and the geophysical corrections (inverse barometer, sea state bias, wet and dry troposphere and ionosphere, wind and tides effect) normally applied to the altimetry record can be less accurate in shallow waters. However, recent efforts from the coastal altimetry community2 have shown that altimetry observations can be reprocessed for coastal regions. An example is the X-TRACK product from AVISO (Birol et al., 2017), which covers 24 coastal regions of the world and ranges from 1993-02 until 2019-05. Two of the defined regions by X-TRACK cover the Atlantic South-American coast (Figure 2).

The aim of this project is to characterize present-day sea-level change in the coast of Brazil, using the X-TRACK product in combination with the tide gauge data from SIMCosta. The student will process the altimetry dataset and validate it with the tide gauge data, obtaining a regional time-series of sea-level anomalies. The final time-series will be used to answer the question “How has sea level changed along the coast of Brazil in the last 28 years?” Other sub-questions, as “Do different regions present a different trends/behavior?”, can also be investigated.

While the X-TRACK processing has been validated in other regions (e.g. Birol et al., 2017), the altimetry product needs to be validated for the Brazilian and South American region. For this, we will use the tide gauge data from SIMCosta. To our knowledge, there is no study that describes present-day sea-level change in the coast of Brazil. Therefore, this study is innovative, and can bring a significant contribution to the scientific and policy-makers community.

Fig. 1. Location of the SIMCosta tide gauges, and a plot of the available time-series (© Carolina Camargo). Fig. 2. Coastal altimetry ground-tracks from X-TRACK product of the AMAZON (orange) and ASA (grey) regions (© Carolina Camargo).
Requirements

This is a project suited to a master student. The student should be familiar with some programming language (preferably Python, but also MatLab or R). Expected project duration is 6 - 9 months (e.g. for a master thesis). This project works with data that are available online (e.g. tide gauges and satellite altimetry). No field work or experimental work is foreseen, only computer work.

More information & contact

Daily supervisor of the project is Carolina Camargo, MSc (PhD candidate), with Dr. Aimée Slangen and Dr. Theo Gerkema as co-supervisors. The project is in collaboration with SIMCosta. For more information and to apply, please contact Carolina Camargo (carolina.camargo@nioz.nl).

References

Birol F., N. Fuller, F. Lyard, M. Cancet, F. Niño, C. Delebecque, S. Fleury, F. Toublanc, A. Melet and M. Saraceno, F. Leger, 2017. Coastal applications from nadir altimetry: example of the X-TRACK regional products. Advances in Space Research, https://doi.org/10.1016/j.asr.2016.11.005.

1 http://www.simcosta.furg.br/

2 https://www.coastalaltimetry.org/