Impact of ENSO on Variability of the Total Ozone Column Over the Northeast Region of Brazil - Part 2: La Niña Canonical and Modoki

Abstract

This study presents a second stage of the spatio-temporal assessment of long-term trends in ozone concentrations in Northeast Brazil (NEB) under the influence of the El Niño - South Oscillation (ENSO) with emphasis on the La Niña phase (Canonical and Modoki). The objective is to analyze the annual variation and the effects of this phenomenon in the Total Ozone Column (TOC) over the NEB, between 1997 and 2018. The data come from remote sensing, generated by the Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) sensors, made available by National Aeronautics and Space Administration (NASA), and analyzed using mean, anomaly values and hovmoller diagrams. It was found that La Niña events cause, predominantly, an increase in the concentration of ozone over the NEB. During periods of action of this mode of variability, the deceleration of Brewer-Dobson circulation (CBD) is caused by the intensification of trade winds, generating ozone accumulation in the tropical region. Between the two modalities, Modoki show this effect more intensified. The highest (+6.5) and lowest (-3.0) average monthly anomaly values obtained occurred during his performance, recorded in the northern region of NEB in July and September, respectively.

Keywords:
total ozone; stratosphere; northeastern Brazil