The Midlatitude Lower-Stratospheric Mountain Wave “Valve Layer”

Boundary-layer friction in midlatitude cyclone

Boundary-layer friction in midlatitude cyclones

Results from an idealized three-dimensional baroclinic life-cycle model are interpreted in a potential vorticity (PV) framework to identify the physical mechanisms by which frictional processes acting in the atmospheric boundary layer modify and reduce the baroclinic development of a midlatitude storm. Considering a life cycle where the only non-conservative process acting is boundary-layer fri...

Liquid particle composition and heterogeneous reactions in a mountain wave Polar Stratospheric Cloud

Mountain wave polar stratospheric clouds (PSCs) were detected on 8 February 2003 above the Scandinavian Mountains by in-situ instruments onboard the M55 Geophysica aircraft. PSC particle composition, backscatter and chlorine activation for this case are studied with a recently developed non-equilibrium microphysical box model for liquid aerosol. Results from the microphysical model, run on quas...

The relationship between tropospheric wave forcing and tropical lower stratospheric water vapor

Using water vapor data from HALOE and SAGE II, an anti-correlation between planetary wave driving (here expressed by the mid-latitude eddy heat flux at 50 hPa added from both hemispheres) and tropical lower stratospheric (TLS) water vapor has been obtained. This appears to be a manifestation of the inter-annual variability of the BrewerDobson (BD) circulation strength (the driving of which is g...

The Evolution of a Stratospheric Wave Packet

This work examines the extent to which a few basic concepts that apply to plane waves, for example, the refraction of waves up the gradient of the index of refraction, apply to stratospheric planetary waves. This is done by studying the relation between group velocity (Cg) and the wave activity velocity, which is defined as the Eliassen–Palm flux divided by the wave activity density (Va 5 F/A)....