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About

I studied Astronomy in a 4-years 1st degree (FCUP-UP, 1998) followed by a master degree in computational methods (FEUP-UP, 2000) and a PhD in Surveying Engineering (UP, 2006) [Thesis: Sea level change in the North Atlantic from tide gauges and satellite altimetry]. After a postdoc in Israel where I worked on the analysis of radon time series I became interested on the use of radon gas as a geophysical proxy and as a tracer of dynamic processes in the Earth's system.

I edited a book on "Nonlinear Time Series Analysis in the Geosciences - Applications in Climatology, Geodynamics and Solar-Terrestrial Physics", and 3 topical volumes. I'm the author of 3 book chapters and 50 papers in international peer-reviewed journals.

 

My research is highly interdisciplinary, with a strong emphasis on data science, particularly time series analysis of environmental data. I have expertise on the analysis of climate records and satellite data, focusing on the assessment and quantification of climate change (trends, changes in seasonality, extremes). I have also experience on the field monitoring of environmental radioactivity (in soil, air and water) and on the analysis and interpretation of radiation variability in the context of Sun-Earth interactions as well as interactions between the different sub-components of the Earth's system.

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Publications

2018

Meteorological and soil surface effects in gamma radiation time series - Implications for assessment of earthquake precursors

Authors
Barbosa, S; Huisman, JA; Azevedo, EB;

Publication
Journal of Environmental Radioactivity

Abstract
Monitoring of environmental radioactivity for the purpose of earthquake prediction requires the discrimination of anomalies of non-tectonic origin from seismically-induced anomalies. This is a challenging task as time series of environmental radioactivity display a complex temporal pattern reflecting a wide range of different physical processes, including meteorological and surface effects. The present study is based on the detailed time series of gamma radiation from the Eastern North Atlantic (ENA) site in the Azores, and on very high resolution precipitation intensity and soil moisture time series. The results show that an abrupt shift in the average level of the gamma radiation time series previously reported as a potential earthquake precursor can also be explained by a corresponding abrupt change in soil moisture. It was concluded that the reduction of false positive earthquake precursors requires the detailed assessment of both precipitation and soil moisture conditions at high temporal resolution. © 2018 Elsevier Ltd

2018

Variabilidade de alta frequência do radão num ambiente interior estável

Authors
Barbosa, SM; et. al.,;

Publication
Proteção contra radiações na comunidade dos países de língua portuguesa

Abstract

2018

Development of a new system for real-time detection of radon using scintillating optical fibers

Authors
Monteiro, CS; Coelho, L; Barbosa, SM; Guimarães, D;

Publication
Optics InfoBase Conference Papers

Abstract
A remote sensor for radon continuous measurement using polymeric scintillation optical fibers was developed and evaluated. Successful preliminary results showed detection of natural occurring radon from a container with rocks rich in uranium oxides. © OSA 2018 © 2018 The Author(s)

2017

Vertical land motion and sea level change in Macaronesia

Authors
Mendes, VB; Barbosa, SM; Romero, I; Madeira, J; da Silveira, AB;

Publication
GEOPHYSICAL JOURNAL INTERNATIONAL

Abstract
This study addresses long-term sea level variability in Macaronesia from a holistic perspective using all available instrumental records in the region, including a dense network of GPS continuous stations, tide gauges and satellite observations. A detailed assessment of vertical movement from GPS time series underlines the influence of the complex volcano-tectonic setting of the Macaronesian islands in local uplift/subsidence. Relative sea level for the region is spatially highly variable, ranging from -1.1 to 5.1 mm yr(-1). Absolute sea level from satellite altimetry exhibits consistent trends in the Macaronesia, with a mean value of 3.0 +/- 0.5 mm yr(-1). Typically, sea level trends from tide gauge records corrected for vertical movement using the estimates from GPS time series are lower than uncorrected estimates. The agreement between satellite altimetry and tide gauge trends corrected for vertical land varies substantially from island to island. Trends derived from the combination of GPS and tide gauge observations differ by less than 1 mm yr(-1) with respect to absolute sea level trends from satellite altimetry for 56 per cent of the stations, despite the heterogeneity in length of both GPS and tide gauge series, and the influence of volcanic-tectonic processes affecting the position of some GPS stations.

2017

Short-term variability of gamma radiation at the ARM Eastern North Atlantic facility (Azores)

Authors
Barbosa, SM; Miranda, P; Azevedo, EB;

Publication
Journal of Environmental Radioactivity

Abstract
This work addresses the short-term variability of gamma radiation measured continuously at the Eastern North Atlantic (ENA) facility located in the Graciosa island (Azores, 39N; 28W), a fixed site of the Atmospheric Radiation Measurement programme (ARM). The temporal variability of gamma radiation is characterized by occasional anomalies over a slowly-varying signal. Sharp peaks lasting typically 2–4 h are coincident with heavy precipitation and result from the scavenging effect of precipitation bringing radon progeny from the upper levels to the ground surface. However the connection between gamma variability and precipitation is not straightforward as a result of the complex interplay of factors such as the precipitation intensity, the PBL height, the cloud's base height and thickness, or the air mass origin and atmospheric concentration of sub-micron aerosols, which influence the scavenging processes and therefore the concentration of radon progeny. Convective precipitation associated with cumuliform clouds forming under conditions of warming of the ground relative to the air does not produce enhancements in gamma radiation, since the drop growing process is dominated by the fast accretion of liquid water, resulting in the reduction of the concentration of radionuclides by dilution. Events of convective precipitation further contribute to a reduction in gamma counts by inhibiting radon release from the soil surface and by attenuating gamma rays from all gamma-emitting elements on the ground. Anomalies occurring in the absence of precipitation are found to be associated with a diurnal cycle of maximum gamma counts before sunrise decreasing to a minimum in the evening, which are observed in conditions of thermal stability and very weak winds enabling the build-up of near surface radon progeny during the night. © 2017 Elsevier Ltd