Modulation of the connection between boreal winter ENSO and the South Asian high in the following summer by the stratospheric quasi-biennial oscillation

• Published in: Journal of geophysical research. Atmospheres 2015-08, Vol.120 (15), p.7393-7411
• Main Authors: Xue, Xu, Chen, Wen, Chen, Shangfeng, Zhou, Dingwen
• Format: Article
• Language: English
• Subjects: Anomalies; El Nino; El Nino phenomena; El Nino-Southern Oscillation event; ENSO; Geophysics; Indian Ocean; Marine; Meteorology; Modulation; Ocean currents; Ocean temperature; Ocean-atmosphere interaction; Oceans; Phase transitions; QBO; Quasi-biennial oscillation; Sea surface; Sea surface temperature; South Asian High; Southern Oscillation; SST; Stratosphere; Summer; Surface temperature; Titanium dioxide; Tropical circulation; Tropical climate; tropical Indian Ocean; Variability; Walker circulation; Weather forecasting; Winter
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1002/2015JD023260

This study investigated the modulation effect of boreal winter quasi‐biennial oscillation (QBO) on the connection between winter El Niño–Southern Oscillation (ENSO) events and the variability of the following summer's South Asian high (SAH) by using European Centre for Medium‐Range Weather Forecasts Interim Reanalysis data for the period of 1979–2013. The results suggest that the boreal summer SAH is more significantly influenced by preceding ENSO events in the easterly phase of the QBO than in the westerly phase. The change in the ENSO‐SAH relationship in the different QBO phases may be attributable to the change in the ENSO‐induced sea surface temperature (SST) anomalies over the tropical Indian Ocean (TIO). Specifically, ENSO's influence on the following summer's TIO SST is more significant when the QBO is in its easterly phase than westerly phase. Further analysis showed that the change in the connection between ENSO and the TIO SST in the different QBO phases may be attributable to change in the anomalous tropical Indian Ocean cell (IOC) associated with ENSO. In particular, the anomalous IOC induced by anomalous Walker circulation over the tropical Pacific is stronger and located further west in QBO easterly than westerly phase. This leads to stronger descending motion and larger SST anomalies over the TIO in the QBO easterly phase. These larger SST anomalies over the TIO in the QBO easterly phase could exert a more significant influence on the tropospheric temperature through moist adjustment, which subsequently results in stronger SAH variability. Key Points The ENSO‐SAH relationship is modulated by the QBO ENSO's influence on the TIO SST is more significant in QBO easterly phase The anomalous IOC associated with ENSO contributes to the QBO modulation