Revisiting Tropical Instability Wave Variability in the Atlantic Ocean using SODA reanalysis
Hatsue Takanaca de Decco1, Audalio Rebelo Torres Junior2, Luciano Ponzi Pezzi3, and Luiz Landau11Laboratório de Métodos Computacionais em Engenharia (LAMCE) , Instituto Alberto Luiz Coimbra de Pós - Graduação e Pesquisa em Engenharia , Universidade Federal do Rio de Janeiro , Postal Code 68.55, Rio de Janeiro – RJ, Brazil , 21941-972 2Laboratório de Modelagem de processos Marinhos e Atmosféricos (LAMMA) , Departamento de Meteorologia, Universidade Federal do Rio de Janeiro , Rio de Janeiro, Brazil , ZIP Code: 21949 - 900 3nstituto Nacional de Pesquisas Espaciais (INPE) , SERE II – OBT , Instituto Nacion al de Pesquisas Espaciais – INPE , Av. dos Astronautas, 1758 , São José dos Campos – SP , ZIP Code: 12227-010
Received: 12 Oct 2016 – Accepted for review: 08 Nov 2016 – Discussion started: 15 Nov 2016
Abstract. The spatial and temporal variability of energy exchange in Tropical Instability Waves (TIWs) in the Atlantic Ocean were investigated. A spectral analysis was used to filter the 5-day mean results from Simple Ocean Data Assimilation reanalysis spanning from 1958 to 2008. TIWs were filtered over periods of 15 to 60 days and between wavelengths of 4 and 20 longitude degrees. The main approach of this study was the use of bidirectionally filtered TIW time series as the perturbation fields, and the difference in these time series from the SODA total results was considered to be the basic state for energetics analysis. The main result was that the annual cycle (period of ~ 360 days) was the main source of variability of the waves, and the semi-annual cycle (period of ~ 180 days) was a secondary variation, which indicated that TIWs occurred throughout the year but with intensity that varies seasonally. Barotropic instability acts as the mechanism that feeds and extracts energy to/from TIWs as alternate zonal bands at equatorial Atlantic. Baroclinic instability is the main mechanism that extracts energy from TIWs to the equatorial circulation north of Equator. All TIW patterns of variability were observed at west of ~ 10º W. The present study reveals new evidences regarding TIW variability and suggests that future investigations should include a detailed description of TIW dynamics as part of Atlantic Ocean equatorial circulation
Takanaca de Decco, H., Rebelo Torres Junior, A., Ponzi Pezzi, L., and Landau, L.: Revisiting Tropical Instability Wave Variability in the Atlantic Ocean using SODA reanalysis, Ocean Sci. Discuss., doi:10.5194/os-2016-84, 2016.