Detailed evolution of warm conveyor belt ascent and associated upper-level potential vorticity field in a convection-resolving simulation

• Main Author: Oertel, Annika
• Other Authors: Wernli, Heini
• Format: Moving Image (Video)
• Language: English
• Published: ETH Zurich 2020
• Subjects: North Atlantic
• Online Access: https://hdl.handle.net/20.500.11850/392157; https://doi.org/10.3929/ethz-b-000392157

Warm conveyor belts are typically described as coherent ensemble of slowly and slantwise ascending trajectories. However, rapid quasi-vertical convective ascent can be embedded within the region of larger-scale WCB ascent. This WCB-embedded convection can be represented by online trajectories in high-resolution convection-resolving simulations of the atmospheric flow. The strong diabatic processes associated with WCB ascent and its embedded convection strongly modify the potential vorticity (PV) distribution. The animations show the evolution of detailed WCB ascent and the according upper-level PV distribution. The animations are based on a 2-km convection-resolving COSMO simulation of a WCB case study in September 2016 in the North Atlantic and cover the time period from 16 UTC 22 Sep to 12 UTC 24 Sep (with a temporal resolution of 15 minutes for the individual frames). The first animation shows the locations of WCB air parcel ascent (circles; colors indicate the centered 2-h pressure change (Δp2h) along all ascending WCB trajectories, in hPa), sea level pressure (grey contours, in hPa) and 2-PVU at 320 K (red line). Pressure changes exceeding 320 hPa in 2 h can be considered as convective WCB ascent (orange and red circles). The second animations shows the according upper-level PV field at 320 K and sea level pressure (grey contours, in hPa) for the WCB ascent presented in the first animation. See https://doi.org/10.1002/qj.3500 and https://doi.org/10.5194/wcd-2019-3 for more information. convection-resolving 2-km COSMO simulation