Speakers
Description
The formation of ice clouds (cirrus clouds) in the tropopause region
requires moderate or even high vertical velocities up to several m/s
when homogeneous freezing is involved. Such vertical velocities result
from convective updrafts, turbulence or gravity waves. However, all
those processes are only purely represented in the tropopause region
of climate models. This in turn leads to misrepresentation of the
temporal and spatial variability of cirrus clouds in climate models
and consequently to increased uncertainties in the radiative effect of
the clouds.
In a recent study the asymptotic analyses of the interactions between
gravity waves and cirrus clouds revealed simplified equations for the
description of ice formation and ice dynamics forced by gravity
waves. Based on this study, here we present an approach for the self
consistent coupling of an existing transient GW parameterization to
cirrus parameterization. Idealized experiments of wave packet
propagation within an ice supersaturated region show a high agreement
in the cirrus evolution between the wave-resolving and
wave-parameterized simulation. Implications of the above results for
the cirrus parameterization in climate models will be discussed.
