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Details

Details

039
Publications

2023

Precipitation-Driven Gamma Radiation Enhancement Over the Atlantic Ocean

Authors
Barbosa, S; Dias, N; Almeida, C; Silva, G; Ferreira, A; Camilo, A; Silva, E;

Publication
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES

Abstract
Gamma radiation over the Atlantic Ocean was measured continuously from January to May 2020 by a NaI(Tl) detector installed on board the Portuguese navy's ship NRP Sagres. Enhancements in the gamma radiation values are identified automatically by an algorithm for detection of anomalies in mean and variance as well as by visual inspection. The anomalies are typically +50% above the background level and relatively rare events (similar to<10% of the days). All the detected anomalies are associated with simultaneous precipitation events, consistent with the wet deposition of scavenged radionuclides. The enhancements are detected in the open ocean even at large distances (+500 km) from the nearest coastline. Back trajectories reveal that half of these events are associated with air masses experiencing continental land influences, but the other half do not display evidence of recent land contact. The enhancements in gamma radiation very far from land and with no evidence of continental fetch from back trajectories are difficult to explain as resulting only from radionuclides with a terrestrial source such as radon and its progeny. Further investigation and additional measurements are needed to improve understanding on the sources of ambient radioactivity in the open ocean and assess whether gamma radiation in the marine environment is influenced not only by radionuclides of terrestrial origin, but also cosmogenic radionuclides, like Beryllium-7, formed in the upper atmosphere but with the ability to be transported downward and serve as a tracer of the aerosols to which it attaches. Plain Language Summary Radioactive elements such as the noble gas radon and those produced by its radioactive decay are naturally present in the environment and used as tracers of atmospheric transport and composition. In particular, the noble gas radon, being inert and of predominantly terrestrial origin, is used to identify pristine marine air masses with no land contamination. Precipitation over land typically brings radon from the atmosphere to the surface, enhancing gamma radiation on the ground, but such enhancements have not been identified before nor expected over the ocean due to the low amount of radon typical of marine air masses. Here we report, for the first time, gamma radiation enhancements associated with precipitation in the oceanic environment, using measurements performed over the Atlantic Ocean in a campaign onboard the Portuguese navy ship NRP Sagres.

2023

GeoTec: A System for 3D Reconstruction in Underground Environment (Aveleiras Mine, Monastery of Tibães, NW Portugal)

Authors
Pires, A; Dias, A; Rodrigues, P; Silva, P; Santos, T; Oliveira, A; Ferreira, A; Almeida, J; Martins, A; Chaminé, I; Silva, E;

Publication
Advances in Science, Technology and Innovation

Abstract

2022

3DupIC: An Underwater Scan Matching Method for Three-Dimensional Sonar Registration

Authors
Ferreira, A; Almeida, J; Martins, A; Matos, A; Silva, E;

Publication
SENSORS

Abstract
This work presents a six degrees of freedom probabilistic scan matching method for registration of 3D underwater sonar scans. Unlike previous works, where local submaps are built to overcome measurement sparsity, our solution develops scan matching directly from the raw sonar data. Our method, based on the probabilistic Iterative Correspondence (pIC), takes measurement uncertainty into consideration while developing the registration procedure. A new probabilistic sensor model was developed to compute the uncertainty of each scan measurement individually. Initial displacement guesses are obtained from a probabilistic dead reckoning approach, also detailed in this document. Experiments, based on real data, demonstrate superior robustness and accuracy of our method with respect to the popular ICP algorithm. An improved trajectory is obtained by integration of scan matching updates in the localization data fusion algorithm, resulting in a substantial reduction of the original dead reckoning drift.

2022

Microplastics Contamination of Large Pelagic Fish in the Open Atlantic Ocean

Authors
Pereira, R; Rodrigues, SM; Silva, D; Freitas, V; Almeida, CMR; Camilo, A; Barbosa, S; Silva, E; Ramos, S;

Publication
SIBIC 2022

Abstract

2022

An holistic monitoring system for measurement of the atmospheric electric field over the ocean - the SAIL campaign

Authors
Barbosa, S; Dias, N; Almeida, C; Amaral, G; Ferreira, A; Lima, L; Silva, I; Martins, A; Almeida, J; Camilo, M; Silva, E;

Publication
OCEANS 2022

Abstract
The atmospheric electric field is a key characteristic of the Earth system. Despite its relevance, oceanic measurements of the atmospheric electric field are scarce, as typically oceanic measurements tend to be focused on ocean properties rather than on the atmosphere above. This motivated the set-up of an innovative campaign on board the sail ship NRP Sagres focused on the measurement of the atmospheric electric field in the marine boundary layer. This paper describes the monitoring system that was developed to measure the atmospheric electric field during the planned circumnavigation expedition of the sail ship NRP Sagres.

Supervised
thesis

2022

Coordination Control of a Robotic Lander

Author
DAVID EMANUEL PRAZERES CARVALHO

Institution
IPP-ISEP

2021

Sistema de localização relativa de um sistema robótico subaquático

Author
JOSÉ PEDRO ALMEIDA MARQUES DE OLIVEIRA

Institution
IPP-ISEP

2021

Estudo e desenvolvimento de protótipos para estimação da velocidade de veículos autónomos submarinos

Author
MURILLO PRESTES VILLA

Institution
IPP-ISEP

2021

Study and development of prototypes for velocity estimation of autonomous underwater vehicles

Author
MURILLO PRESTES VILLA

Institution
IPP-ISEP

2020

Object Detection and Tracking for ASV

Author
DIMPI RAJUBHAI PATEL

Institution
IPP-ISEP