Virtual Workshop: Warm Conveyor Belts – a challenge to forecasting

This presentation summarizes the key findings using airborne observations with active remote-sensing instruments that were applied to observe WCBs. A focus is put on observations that were made during the North Atlantic Waveguide and Downstream impact EXperiment (NAWDEX) that was conducted in autumn 2016 with the aim to examine the structure of the jet stream, the impact of diabatic processes...

The strong diabatic processes during warm conveyor belt (WCB) ascent modify the potential vorticity (PV) distribution, which can subsequently influence the large-scale flow evolution. According to the classical concept, WCBs rise continuously from the boundary layer to the upper troposphere with ascent rates of less than 50 hPa/h and thereby predominantly form stratiform clouds. Recent studies...

This presentation introduces a quantitative potential-vorticity (PV) framework to quantify the processes governing the amplification of forecast errors and forecast uncertainty. The framework is based on the well-established PV perspective of midlatitude dynamics. A tendency equation is derived for error-potential enstrophy and applied to a series of numerical upscale error-growth experiments,...