Propagation Characteristics and Impacts of the Atmospheric Kelvin Wave during Qbo Anomaly

The Quasi-Biennial Oscillation (QBO) is a regular variation of the zonal wind that blows in the stratosphere above the equator. Strong eastward and westward winds in the region completely change direction alternatively. The full cycle takes roughly 28 months, making it the most regular slow variation in the atmosphere since 1953 when QBO has been constantly documented. Unexpectedly, the evolution of QBO during the Northern hemisphere winter of 2015-2016 shows different features. A band of the westward wind began to form above the eastward wind, as expected, at the end of 2015, but it was cut off by a new band of the eastward wind that appeared below it, keeping the QBO from completing a normal cycle. Propagation of planetary scale Rossby waves from the NH mid-latitudes into the tropical region and the strong 2015-2016 ENSO effects may be the clues to the causes of this QBO anomaly. Because the QBO is forced by the interaction of Kelvin waves and mixed Rossby-gravity waves with the zonal mean flow, we are going to study the propagation characteristics of the atmospheric Kelvin waves during this QBO anomaly. Moreover, propagation features of ultra-fast Kelvin waves that travel to the ionosphere will also be investigated to examine with more ionospheric disturbances. The whole research project contents three phases, and this is the third phase. In the first two phases, we have studied the properties of Kelvin waves and further their propagation in the stratosphere, mesosphere, and lower thermosphere. The interactions between Kelvin waves and the background zonal winds have also been investigated. Therefore, in this 3rd phase, we will use total electron content and ionosonde data to find out the impacts of ultra-fast Kelvin waves on the ionosphere. The results of this project will further promote the study on the atmosphere-ionosphere coupling.