Abstract
The quasi-geostrophic relation between the fluxes of momentum, potential vorticity and potential temperature is tested with atmospheric data by computing the convergence of momentum flux as a residual of of the potential temperature and potential vorticity flux and comparing it to the momentum flux convergence computed directly. It is shown that in the troposphere between 18 and 74°N the observed momentum flux convergence differs from the quasi-geostrophic convergence by 25–60% depending on tropospheric level and season.