Wave Breaking Events and Their Link to Rossby Wave Packets and Atmospheric Blockings During Southern Hemisphere Summer

Rossby Wave Packets (RWPs) are atmospheric perturbations located at upper levels in mid-latitudes which, in certain cases, terminate in Rossby Wave Breaking (RWB) events. When sufficiently persistent and spatially extended, these RWB events are synoptically identical to atmospheric blockings, which are linked to heatwaves and droughts. Thus, studying RWB events after RWPs propagation and their link with blocking is key to enhance extreme weather events detection 10-30 days in advance. Hence, here we assess (a) the occurrence of RWB events after the propagation of transient RWPs, (b) whether long-lived RWPs (RWPs with a lifespan above 8 days, or LLRWPs) are linked to large-scale RWB events that could form a blocking event, and (c) the proportion of blocking situations that occur near RWB events. To do so, we applied a tracking algorithm to detect transient RWPs in the southern hemisphere during summertime between 1979 and 2021, developed a wave breaking algorithm to identify RWB events, and searched for blocking events with different intensities. Results show that LLRWPs and the other RWPs displayed large-scale RWB events around 40% of the time, and most RWB events in both distributions last around 1-2 days, which is not long enough to identify them as blocking situations. Nearly 17% of blockings have a RWB event nearby, but barely 5% of blockings are linked to RWPs, suggesting that transient RWPs are not strongly linked to blocking development. Lastly, large-scale RWB events associated with RWPs that lasted less than 8 days are influenced by El Nino-Southern Oscillation. When an atmospheric wave breaks in the upper levels of the atmosphere, it modifies the wind flow in the upper atmosphere and can drastically change local weather conditions. If wave breaking events are sufficiently big and stable, they can produce atmospheric blocking events, which are linked to heatwaves and drought development. Here, we assess whether a link between wave breaking events caused by long-lived traveling atmospheric waves (waves that last more than 8 days in the atmosphere) and blocking event development exists during southern hemisphere summer. Independently of the duration of the wave packets, near 4 out of 10 times they cause very extensive wave breaking events, but do not last long enough time in the atmosphere to be considered an atmospheric blocking. Oppositely, nearly 20% of blocking events manifest nearby a wave breaking event independently of the strength of the block, but these wave breaking events do not seem to be linked to traveling wave packets. Therefore, this study suggests that traveling atmospheric waves are not directly related to the development of atmospheric blockings. Also, the occurrence of extensive wave breaking events caused by traveling atmospheric waves that last less than 8 days is influenced by El Nino-Southern Oscillation. Large-scale wave breaking events associated to transient long-lived Rossby waves occur more often in the middle-eastern Pacific basin Transient Rossby Wave Packets do not cause large-scale wave breaking events that last enough to develop into an atmospheric block Near 17% of blocking events appear preceded by a wave breaking event but most of them are not linked to transient Rossby Wave Packets