The Intraseasonal and Interannual Variability of The Coupling Between the South Atlantic Convergence Zone and the Upper Tropospheric Cyclonic Vortex

Abstract

The relationship between the South Atlantic Convergence Zone (SACZ) and the Upper Tropospheric Cyclonic Vortex (UTCV) was analyzed over 34 summers, with positive, negative and neutral phases of El Niño Southern Oscillation. Zonal and meridional wind components anomalies, calculated based on climatology between 1979-2013 at the level of 200 hPa, were submitted to the Lanczos filter for 20-90 days and 200 days low pass bands, with the intention of highlighting intraseasonal and interannual variability, ensuring three mean compositions of SCAZ referring to the positive, negative and neutral phases of ENSO. The compositions for the intraseasonal and interannual band reveal the intensification of the UTCV for both SACZ-El Niño and SACZ-Neutral, while the interannual variability during SACZ events under La Niña activity inhibit the formation of the UTCV near the continent due to anticyclonic circulation in the area.

Keywords
SACZ; UTCV; La Niña