Science Update: ENSO influence on QBO modulations of the tropical tropopause

W. Yuan and co-authors investigate the influence of the El Niño/Southern Oscillation (ENSO) on the quasi-biennial oscillation (QBO) modulation of cold-point tropopause (CPT) temperatures. Using almost five decades of radiosonde data from eleven near-equatorial stations, they show that the ENSO influence on the QBO is quite zonally symmetric. The data indicate that the QBO has larger amplitude and longer period during La Niña conditions than during El Niño. Their results also indicate that the warmer CPT temperatures during QBO westerly shear conditions and colder temperatures during QBO easterly shear conditions, are larger during La Niña than during El Niño. This strengthens earlier findings that the greatest dehydration of air entering the stratosphere from the troposphere occurs during the winter under La Niña and easterly QBO conditions. The full abstract can be found here.