The QBO and interannual variability of stratospheric inertial instability

The quasi-biennial oscillation (QBO) affects a wide variety of weather and climate phenomena, from hurricanes to Northern Hemisphere winter surface temperatures. In our presentation we demonstrate a previously undiscovered connection between the QBO and stratospheric inertial instability.

Using a climatology of inertial instability based on United Kingdom Met Office (MetO) assimilated analyses from November 1991 through March 2004, we have identified channels of enhanced inertial instability frequency from the stratopause downward into the middle stratosphere.

These inertial instability channels exhibit a QBO signal, both in terms of frequency of inertial instability and in the spatial location of the channels. QBO easterlies tend to promote inertial instability farther poleward, presumably as a result of a poleward shift of the region of maximum anticyclonic shear due to the QBO.

We will discuss the implications of this QBO signal for the location and frequency of tropical-midlatitude transport throughout the middle and upper stratosphere.