What Is a Friction Pump?

What is frictional convergence?

Pumpiman Friction is the buildup in the cyclone planetary boundary layer (low pressure system) that arises due to surface friction during which the wind component cuts isobars from high pressure to low pressure; in an anticyclone (high pressure system) the events that arise are called frictional scattering; friction pump is a type of secondary flow; see Eckman gyre.

Source: Terms in Transportation Meteorology