MMM SEMINAR NCAR
Boundary Layer Friction
in Mid-Latitude Cyclones: More than Ekman Pumping!
Department of Meteorology
How does the atmospheric boundary change the development of synoptic systems? Ekman demonstrated that friction in the atmospheric
boundary layer leads to a vertical motion that reduces the vorticity
of a barotropic vortex. It has often been assumed, at
least implicitly, that this is the mechanism that operates in baroclinic mid-latitude weather systems. In this talk it
will be demonstrated, using a potential vorticity
framework, that Ekman pumping is not the dominant
mechanism. Instead, the dominant effect is through a distinct, baroclinic, generation of potential vorticity
in the boundary layer. This potential vorticity is advected into the troposphere, where it increases the
stability, thus reducing baroclinic growth.
Refreshments 10:15 AM
NCAR-Foothills Laboratory
Bldg 2 Auditorium (Rm.1022)