Estudo de ocorrência de dutos de evaporação na região oceânica ao largo do Estado do Rio Grande do Sul


  • Flávia Rodrigues Pinheiro Centro de Hidrografia da Marinha, Rio de Janeiro, RJ
  • Ricardo Carvalho de Almeida Centro de Monitoramento de Derramamento de Óleo no Mar, Rio de Janeiro, RJ



The purpose of this study is to analyze the occurrence of anomalous electromagnetic propagation conditions near the sea surface, caused by the presence of evaporation ducts offshore the coast of the state of Rio Grande do Sul. Meteorological and oceanographic features typically associated to surface layer conditions favorable for the formation of evaporation ducts will be investigated, aiming at the development of conceptual models applicable to that ocean region. It will be used a surface layer model, based on the Monin-Obukhov similarity theory. Refractivity profiles will be retrieved by applying this model to a data set collected by a mooring buoy offshore Rio Grande harbor. The results of the case study show that the evaporation duct thickness is modulated by conditions associated to the presence of a cold front in the region. That frontal system caused significant changes in the profiles of specific humidity in the surface layer. The propagation of electromagnetic waves in the range of VHF, UHF and microwaves, are usually affected by those changes. Therefore, the performance of radars and communication equipments operating in those frequencies will be affected too.


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How to Cite

Pinheiro, F. R., & Almeida, R. C. de. (2002). Estudo de ocorrência de dutos de evaporação na região oceânica ao largo do Estado do Rio Grande do Sul. Ciência E Natura, 21–44.