Impact of sub-synoptic scale processes in the upper troposphere on Rossby wave evolution
Peter Spichtinger, Universität Mainz
High impact weather situations as long living blocking events or severe storms over the North Atlantic sector and Europe are strongly related to the life cycle of Rossby waves. Although there is consensus that baroclinic life cycles are usually dominated by dry adiabatic processes, in the recent years the impact of diabatic processes associated with clouds in the lower and middle troposphere was investigated intensively. However, effects in the upper troposphere as well as sub-synoptic processes were not taken into account, although it is well known that changes in the upper-level potential vorticity (PV) strongly impact the Rossby wave propagation. It is hypothesized that cirrus clouds in the tropopause region could influence upper-level PV, e.g. via radiative feedbacks, turbulence and/or latent heat release. It is unknown how these processes on sub-synoptic scales will feed back to upper-level PV distribution and erosion. Here, we propose to investigate the impact of sub-synoptic scale processes in the tropopause region. The potential impact of the associated PV anomalies on forecast errors for numerical weather predictions will be quantified. Our main methodologies will be investigations of meteorological data as well as idealized and near-realistic highresolution numerical modelling.