Handout (2.6 MB)
Nevertheless, little is still known about the characteristics of synoptic-scale negative PV. How frequently is it observed? And what are its ‘typical’ impacts on the jet stream?
Focusing on North America where severe convection is frequent, we design an algorithm that tracks the temporal evolution of closed contours of upper-level, negative PV air using ERA5 data. We composites instances in which it is in close-proximity to (‘interacts with’) the jet stream and assess its dynamical response. The role of negative PV on jet evolution and its downstream response over the Atlantic is facilitated through a combination of lagged composite analysis and K-means clustering.
Our composite results in combination with preliminary high-resolution model simulations highlight the following conclusions. Synoptic-scale bands of negative PV frequently interact with the jet stream, intensify jet wind-speed maxima and can serve as an amplification source for Rossby Wave Packets.

