I'm reading articles about climate models for possible exoplanets, and I'm confused as to what the "strength" of a Hadley or Ferrell cell refers to. Does it refer to wind speed? Wind force?
If I recall correctly from my bachelor lectures the strength of the Hadley or Ferrell cells are often described in terms of kg/s (or sverdrup, so 109 kg/s), so i.e. mass flow of air.
I am not sure if this is also used for exoplanets but it is used for the Earth.
Source: Fig. 7.19 on page 159 in https://archive.org/details/peixoto-j.-p.-oort-a.-h.-physics-of-climate-1992/page/159/mode/2up