EGU2020-10398
https://doi.org/10.5194/egusphere-egu2020-10398
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

A more complete Rossby wave source

Wolfgang Wicker1 and Richard Greatbatch1,2
Wolfgang Wicker and Richard Greatbatch
  • 1GEOMAR Helmholtz Centre for Ocean Research Kiel, Ocean Circulation and Climate Dynamics, Germany
  • 2Faculty of Mathematics and Natural Sciences, Kiel University, Germany

Tropical convection drives extratropical variability on subseasonal to interannual time-scales by exciting Rossby wave trains in the upper troposphere. Traditionally the relevant Rossby wave source is considered to be the sum of vortex stretching and vorticity advection by the divergent horizontal flow ( - ∇·uχ (ζ+f) - uχ·∇ (ζ+f)). Since absolute vorticity is very small at the equator, the equatorward flanks of the upper tropospheric jets have been regarded the source region of Rossby wave trains. In these considerations vertical momentum advection is neglected, although, it is an important source for westerly momentum at the equator. The curl of vertical momentum advection is the sum of vertical vorticity advection and vortex tilting ( -  ω ζp - ωx vp + ωy up). These contributions are smaller than the traditional Rossby wave source in midlatidues by about one order of magnitude but they are of similar size in the tropics.

How to cite: Wicker, W. and Greatbatch, R.: A more complete Rossby wave source, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10398, https://doi.org/10.5194/egusphere-egu2020-10398, 2020