[PAOCQ] Talia Tamarin-Brodsky (MIT)

“On atmospheric wave breaking, heatwaves, and everything in between (blocks)”

The atmospheric circulations involve interactions among many different spatial and time scales, and are often decomposed into ‘high’ and ‘low’ frequency variability. For example, the North Atlantic low-frequency variability includes slowly varyingweather regimes, such as the North Atlantic Oscillation or the Atlantic blocked regime, with timescales of days to weeks. The high-frequency variability includes the synoptic weather systems, which shape our daily weather fluctuations. The interaction between timescales is often mediated by Rossby wave breaking events, in which large amplitude waves irreversibly break and dissipate, while modifying the large-scale circulation. Breaking events are thus closely related to persistent blocking events, which in turn are often associated with extreme and persistent surface temperatures. What contributes to the persistence and termination of blocking events, and similarly for heatwaves, remains largely unknown. Here I will present initial attempts to address these questions.

We show that the slowly varying weather regimes influence the tracks of low-level cyclones and anticyclones, which in turn, depending on the position relative to the low-frequency background flow, determines if wave breaking is enhanced or suppressed. The slowly varying weather regimes exhibit clear positive feedback with the high frequency flow during breaking events. For heatwaves associated with persistent blocks, we examine which mechanisms, such as convective instability and precipitation, can ultimately lead to the termination of the heatwave and associated block.

PAOC Colloquium —

Interdisciplinary seminar series that brings together the whole PAOC (Program in Atmospheres, Oceans, and Climate) community. Seminar topics include all research concerning the physics, chemistry, and biology of the atmospheres, oceans and climate, as well as talks about societal impacts of climatic processes.

Contact: paoc-colloquium-comm@mit.edu