EGU General Assembly 2021
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Environmental radioactivity in the Atlantic marine boundary layer from the SAIL monitoring campaign  

Susana Barbosa1, Guiherme Amaral1, Carlos Almeida1, Nuno Dias1, António Ferreira1, Mauricio Camilo2, and Eduardo Silva1
Susana Barbosa et al.
  • 1INESC TEC, Porto, Portugal
  • 2Marinha, CINAV (Centro de Investigação Naval), Portugal

Ambient radioactivity reflects a wide range of physical processes, including atmospheric and geological processes, as well as space weather and solar conditions. Gamma radiation near the Earth’s surface comes from diverse sources, including space (cosmic radiation), the earth’s atmosphere, and solid earth. In addition to the terrestrial gamma radiation originating from the radioactive decay of primordial radionuclides present in every soil and rock, gamma radiation is also continuously produced in the atmosphere from the interaction of secondary cosmic rays and upper-atmosphere gases, as well as from the decay of airborne radon (Rn-222) progeny. Therefore the temporal variability of gamma radiation contains information on a wide range of physical processes and space-earth interactions, but disentangling the different contributions remains a challenging endeavor. Continuous monitoring of gamma radiation at sea enables to remove both the terrestrial and radon exhalation contributions, allowing to examine in detail the space and atmospheric sources of ambient gamma radiation.

Gamma radiation over the Atlantic Ocean was measured on board the ship-rigged sailing ship NRP Sagres in the framework of the SAIL (Space-Atmosphere-Ocean Interactions in the marine boundary Layer) project. The measurements were performed continuously (every 1-second) with a NaI(Tl) scintillator counting all the gamma rays from 475 keV to 3 MeV. The casing of the instrument was adapted in order to endure the harsh oceanic conditions and installed in the mizzen mast of the ship. The counts were linked to a rigorous temporal reference frame and precise positioning through GNSS.

Here preliminary results based on the gamma radiation measurements performed from January 5th to May 9th 2020 are presented, corresponding to the journey of the ship from Lisboa to Cabo Verde, Rio de Janeiro, Montevideu, Cape Town, and back to Lisboa. The data exhibit a clear transition from the coastal to the marine environment, enabling to study in detail the temporal variation of gamma radiation in the marine boundary layer, as well as the interface between land and marine conditions in terms of environmental radioactivity.

How to cite: Barbosa, S., Amaral, G., Almeida, C., Dias, N., Ferreira, A., Camilo, M., and Silva, E.: Environmental radioactivity in the Atlantic marine boundary layer from the SAIL monitoring campaign  , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1264,, 2021.

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