Uncertainties of the relationship between the equatorial quasi-biennial oscillation, the Arctic stratosphere and solar forcing

Two different equatorial quasi-biennial oscillation (QBO) indices, two reanalyses and radiosonde observations are used to analyze the Arctic stratospheric temperature and height. This analysis was used to assess the uncertainties in the connection of solar forcing, QBO and the Arctic variability. The results show that (1) the frequency of the westerly/easterly phases of the QBO over the stratospheric equator has a significant multiple peak seasonal variation. The primary seasonal peaks occur in February, March and April for the westerly phase of the QBO and the easterly phase peaks in June, July and August. (2) The correlation of stratospheric Arctic temperature and height with the solar radio flux shows statistical significance in February or July/August even if there is no stratified phase of QBO (easterly and westerly phases) involved. However, when the correlation was computed according to the stratified phase of QBO, the solar signals in both temperature and height fields are remarkably amplified in February and November under the westerly phase, but the signal in the height field is most significant only in August under the easterly phase. (3) The impact of the QBO and solar forcing on the stratospheric temperature and heights in the Arctic varies depending on the season. The impacts are also sensitive to the specific height of the QBO-defined level that is used, the specific period of the analysis and the dataset used.

Research Highlights
► The uncertainties in the connection of solar forcing, QBO and the Arctic variability were assessed.
► The uncertainty is related to the stratified phase of the QBO.
► The uncertainty comes from the analysis period.
► The uncertainty is associated with the selected height of the QBO index.
► The uncertainty is due to data implementation.