Guilherme de Melo, Federal University of Rio Grande do Norte, Natal, RN, Brazil, Ross Parnell-Turner, Scripps Institution of Oceanography, La Jolla, United States, Robert P Dziak, NOAA, Pacific Marine Environmental Laboratory, Newport, OR, United States, Deborah K Smith, National Science Foundation, Arlington, VA, United States and Aderson Farias do Nascimento, UFRN: Federal University of Rio Grande do Norte, DGEF: Geophysics Department, Natal, Brazil