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- Title
Refratividade Atmosférica em Áreas Oceânicas Baseada em Dados de Sondagem Atmosférica na Região da Ilha de Trindade.
- Authors
Cremonini Baptista, Daniel; Neder Candella, Rogério; de Oliveira-Júnior, José Francisco; Ocimoto Oda, Tânia
- Abstract
The Brazilian coastal region has an intense maritime traffic, composed by several types of ships. The safety of navigation is important and therefore these ships are equipped with communication and detection equipment, and their performances are strongly influenced by the conditions of electromagnetic propagation in the atmosphere. Anomalous conditions in electromagnetic propagation are caused by sharp vertical gradients of atmospheric refractivity, which can be evaluated using the M index. Therefore, the main objective of this work is to evaluate atmospheric refractive conditions and estimate the heights of atmospheric ducts based on this index, using data from atmospheric soundings in the region of Trindade Island, from 2005 to 2016. The results showed the presence of 3348 surface ducts, being approximately 65% of the heights below 220 m. The highest averages of height were observed in the winter months, especially in June and July. The lowest values were observed in December. In the case studies, the evaluation of the thermodynamic profiles showed that on the days with ducts, unstable layers near the ocean surface are presented, and stable layers above them were observed. The synoptic conditions were characterized by the presence of a high pressure system or by the influence of the Subtropical South Atlantic High. In the episode without surface duct, the presence of a frontal system was verified, as well as a null vertical gradient of humidity and the presence of a stable boundary layer, and thus inhibits the formation of ducts.
- Subjects
ATMOSPHERIC acoustics; WEATHER; ATMOSPHERE; HUMIDITY; SHIPS; CONTAINER ships
- Publication
Anuario do Instituto de Geociencias, 2020, Vol 43, Issue 3, p444
- ISSN
0101-9759
- Publication type
Article
- DOI
10.11137/2020_3_444_454