Synoptic Climatologies

Extratropical cyclones (Heini Wernli)

Extratropical cyclones (EC) are meteorological key players in the midlatitudes. We developed a novel method to identify EC in gridded data sets and to compile long-term climatologies. Furthermore, the distinct EC are tracked along their lifecycle with a new tracking technique.

A climatology of Warm Conveyor Belts (Erica Madonna)

During their intensification and in the mature stage, extratropical cyclones are typically associated with three coherent major airstreams – the dry intrusion, the cold conveyor belt and the warm conveyor belt, respectively. These airstreams are important for the dynamics of the cyclone evolution, and potentially also for the rapid long-range transport of atmospheric constituents. They are key for the meridional and vertical transport of water vapor and heat, linking the atmospheric boundary layer and the tropopause region.

In this PhD project a detailed climatology of WCBs is compiled for the 21-year time period of the ERAinterim reanalysis data set (1989-2009). A central aspect of the study is the analysis of the typical evolution of key parameters along the WCB flows, including water vapor, cloud water content (liquid and ice), potential temperature, and potential vorticity.

Precursors of cyclogenesis (Michael Graf)

Many studies indicate a large variability of the relevant physical processes (so-called precursors) responsible for cyclogenesis. For these reason locations of initial cyclone development are objectively determined based upon operational analysis and deterministic forecast data from ECMWF. In the environment of these locations a set of more than 20 precursors is determined. Based on these parameters, determined for a multitude of cyclones, a clustering analysis is performed to categorize the different cyclogenesis events.