A spectral climatology of planetary-scale disturbances in the southern and northern hemispheres: present and future climate scenarios

Planetary-scale disturbances are known to significantly affect the stratospheric and tropospheric circulations through wave interaction with the zonal mean flow. For this reason, it is important to better characterize planetary-scale wave activity to assess how it can affect the current and future climate. In order to better characterize wave activity, we present a climatology based on the longitudinal Fourier decomposition of atmospheric variables such as the height, wind and PV fields. This decomposition technique provides more information than the typical Eulerian average of atmospheric fields. For example, the amplitude, the phase, the phase speed and the vertical and meridional tilt of the planetary-scale disturbances can be derived at each latitude and vertical level. We present a thorough climatology of planetary-scale disturbances in both Southern and Northern hemispheres for the current climate using ERA-Interim and future climate scenarios using CMIP5.