engleski

Cyclogenesis in the Lee of the Atlas Mountains : a factor separation numerical study

The initiation of a deep and severe impact Mediterranean cyclone in the lee of Atlas Mountains is investigated by a series of numerical experiments using the MM5 forecast model. The roles of orography, surface sensible heat flux and upper-level potential vorticity anomaly are identified using factor separation method. Results of model simulations show that orography blocking is responsible for the generation of the low-level shallow vortex in the first phase of lee development. Upper-level potential vorticity anomaly is a principal ingredient of this event, responsible for a dominant deepening effect in the later stage of lee formation. Analysis of cyclone paths shows that orography tends to keep the cyclone stationary, while upper-level dynamical factors are crucial for advection of the system to the Mediterranean Sea. The most noteworthy influence of surface sensible heat flux is identified as afternoon destruction of the surface baroclinic zone and associated weaker cyclogenesis.

cyclogenesis; factor separation method; Atlas mountains; upper-level PV; sensible heat flux

nije evidentirano