Abstract
The Quasi-Biennal Oscillation (QBO) and the El Niño-Southern Oscillation (ENSO) largely modulate the zonal wind in the tropics. Previous studies showed that QBO phases produce changes in deep convection through an increase/decrease in the tropopause height over the tropics and subtropics. This study investigates the combined effects of QBO and ENSO on tropical cyclone activity by modulating tropopause height. We found that tropopause height increases over the Gulf of Mexico, the Caribbean region, and the Western North Atlantic Ocean during La Niña + QBOW, allowing deeper tropical convection to develop over those regions. As a consequence, TC activity over those regions is not only increased in number but also enhanced in intensity. Conversely, during El Niño + QBOE, most deep tropical convection is inhibited over those same regions due to the decrease in tropopause height over the subtropics. We conclude that QBO effects on TCs and deep convection should be studied in combination with ENSO. Additional comparative studies using long record data at high vertical resolution are needed to fully understand to what extent QBO interacts with ENSO in the lower tropical stratosphere and upper tropical troposphere.
Highlights
The Quasi-Biennial Oscillation (QBO) is a stratospheric oscillation of downward propagating wind regimes classified into the westerly phase (QBOW) and the easterly phase (QBOE), each phase lasting ~28 months on average [1]
Under La Niña + QBOW conditions (Figure 3e), tropical cyclone (TC) density is the highest compared to the other El Niño-Southern Oscillation (ENSO)-QBO combinations, while El Niño + QBOE (Figure 3b) is the least active
The largely modulate the zonal wind on the tropics
Summary
The Quasi-Biennial Oscillation (QBO) is a stratospheric oscillation of downward propagating wind regimes classified into the westerly phase (QBOW) and the easterly phase (QBOE), each phase lasting ~28 months on average [1]. Their study demonstrates that QBO modulates tropopause temperatures linked to deep tropical convection over the Atlantic and Indian Oceans, mainly in June-July-August [11] They show that QBO influences the Walker circulation, which is reduced during March–. It is worth mentioning that this study excluded ENSO signal from the analysis, and no significant influence of QBO on TCs over NA was found They suggest the use of longer datasets to provide a more robust physical explanation. Most studies isolate QBO modulation from the ENSO signal, but their interactions and combined influence on TCs have not been analyzed yet.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
