Joint Seminar: Bimodal Evolution of Vertical Motion in Tropical Precipitation Extremes
This study examines the evolution of “top-heaviness” in tropical convection during extreme precipitation events. Top-heaviness describes the extent to which ascent peaks in the upper (top-heavy) versus lower (bottom-heavy) troposphere. Reanalysis vertical velocity profiles are projected onto two sinusoidal basis functions, representing the first and second baroclinic modes, that together characterize top-heaviness. Two distinct modes are found following the peak in rainfall: stratiform decay and convective decay. Stratiform-decay events transition rapidly from bottom-heavy to top-heavy to stratiform-like ascent profiles and experience sharp reductions in instability, moisture and precipitation after the peak of the event. In contrast, convective-decay events sustain bottom-heavy ascent profiles with a gradual decline in instability and moisture and prolonged precipitation; they contribute over 55% of the rainfall during extreme events. These findings emphasize the significant role of convective decay in shaping extreme precipitation compared to conventional stratiform decay.
Datum
20.08.2025
Uhrzeit
13:30 h
Ort
- Bundesstr. 53, room 022/023
- Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg