Preprints
https://doi.org/10.5194/egusphere-2025-1790
https://doi.org/10.5194/egusphere-2025-1790
11 Aug 2025
 | 11 Aug 2025
Status: this preprint is open for discussion and under review for Atmospheric Measurement Techniques (AMT).

Studying anomalous propagation over marine areas using an experimental AIS receiver set-up

Laura Rautiainen, Milla Johansson, Mikko Lensu, Jani Tyynelä, Jukka-Pekka Jalkanen, Ken Stenbäck, Harry Lonka, and Lauri Laakso

Abstract. Automatic Identification System (AIS) is a wireless communication system used by vessels to exchange real-time information with each other and with coastal authorities, enhancing situational awareness and maritime safety. Consequently, safety at sea depends on reliable signal transmission, which can be disrupted by anomalous signal propagation. In particular, tropospheric ducting can extend the AIS antenna horizon, allowing messages to be received over greater distances than under standard conditions. To study the behaviour of the AIS signal under standard and anomalous propagation conditions, 1-year of AIS-observations were collected from two antennae at 7 m and 30 m heights above the mean sea level on the Utö Island in the Baltic Sea. The AIS antennae were co-located with mast-mounted measurements of temperature and humidity. This allows for studying the AIS signal propagation alongside observed refractivity profiles. The AIS over-the-horizon observations occurred 59 % of the time for the 30 m antenna and 34 % of the time for the 7 m antenna, mainly during the spring and summer months. A strong diurnal cycle was observed in the Archipelago Sea, north of Utö, while no diurnal cycle was observed in the open sea region south of Utö. During periods of anomalous signal propagation, the AIS messages were received from farther away, from up to 600 km from Utö and the observed received signal strength decayed slower with distance, indicating reductions in propagation losses due to ducting. The anomalous AIS observations were also found to coincide with the stronger and higher observed ducts.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
Share
Laura Rautiainen, Milla Johansson, Mikko Lensu, Jani Tyynelä, Jukka-Pekka Jalkanen, Ken Stenbäck, Harry Lonka, and Lauri Laakso

Status: open (until 23 Sep 2025)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-1790', Alex Chartier, 11 Aug 2025 reply
Laura Rautiainen, Milla Johansson, Mikko Lensu, Jani Tyynelä, Jukka-Pekka Jalkanen, Ken Stenbäck, Harry Lonka, and Lauri Laakso
Laura Rautiainen, Milla Johansson, Mikko Lensu, Jani Tyynelä, Jukka-Pekka Jalkanen, Ken Stenbäck, Harry Lonka, and Lauri Laakso

Viewed

Total article views: 512 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
498 9 5 512 13 15
  • HTML: 498
  • PDF: 9
  • XML: 5
  • Total: 512
  • BibTeX: 13
  • EndNote: 15
Views and downloads (calculated since 11 Aug 2025)
Cumulative views and downloads (calculated since 11 Aug 2025)

Viewed (geographical distribution)

Total article views: 506 (including HTML, PDF, and XML) Thereof 506 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 30 Aug 2025
Download
Short summary
We present an experimental Automatic Identification System (AIS) receiver set-up to study anomalous signal propagation over coastal and marine waters in the northern Baltic Sea. Anomalous atmospheric conditions can allow for the AIS messages to be received from farther distances than under normal conditions. The results show that under anomalous conditions, the messages can be received up to 600 km away and have both diurnal and seasonal cycles.
Share