International Workshop on Atmospheric Blocking

Atmospheric blocking describes a flow situation characterized by quasi-stationary and persistent high-pressure systems. These high-pressure systems block the usual mid-latitude westerlies so that low pressure systems embedded therein can be held stationary at the flanks. Blocking events are associated with regional extreme weather events such as heatwaves and cold spells, and flooding. Physical processes involved in blocking are not yet fully understood, and skillful predictions of the formation and maintenance of blocking anticyclones remain a challenge for numerical weather prediction and climate models.

A virtual workshop on the dynamics of atmospheric blocking, co-organized by researchers from IMK-TRO, was held from 27-29 September 2021 [1]. Following the first successful Blocking Workshop in Reading in 2016 [2], this event offered a platform to bring together experts in the field of atmospheric and climate science during the Covid-19 pandemic, to review the current state of research, and to discuss the most important open questions regarding blocking. The idea of organizing this workshop was initiated by “Waves to Weather” scientists Franziska Teubler (at Johannes Gutenberg University, Mainz) and Seraphine Hauser at the Karlsruhe Institute of Technology, Karlsruhe (KIT), in early 2021 with the aim of scientific exchange on atmospheric blocking during the ongoing Covid-19 pandemic. The Transregional Collaborative Research Center “Waves to Weather” [3] volunteered to sponsor and host the workshop and was highly involved in the organization and planning of the event. The organizing committee that additionally consisted of Volkmar Wirth (at Johannes Gutenberg University, Mainz) and Daniel Steinfeld (at University of Bern, Switzerland), was supported by a scientific committee led by Dr. Christian Grams (KIT, IMK-TRO).

The focus of this online workshop was set on the understanding of dynamics and physical processes in atmospheric blocking, with special focus on (i) the role of dry and moist dynamics in the formation, maintenance, and decay of blocking, (ii) teleconnections and external forcing modulating the occurrence of blocking, and (iii) model representation and predictability of blocking dynamics and physical processes. With nearly 60 contributions by scientists from all parts of the world and with more than 170 participants, the workshop attracted a lot of international attention. The 3-day program of the workshop consisted of seven oral sessions, introduced by renowned keynote speakers, two poster sessions and two breakout group discussions dedicated to the topics mentioned above. We were particularly happy about an honorary lecture by Sir Brian Hoskins, who gave an overview of the history of research on blocking. Overall, the workshop went smoothly without technical difficulties, and although the program was very dense, there was enough time for further exchange during the coffee breaks.

Regarding the content of the discussions and breakout sessions, the major takeaway is that blocking still is a very complex phenomenon with processes on different spatial and temporal scales involved. There is not one process dominating, but mutual interactions and case-to-case variability in pathways to blocking. Recent studies, which were presented at the workshop, contribute to an improved understanding of the dynamics of blocking. It remains our duty as a community to map out the variability of pathways that lead to the formation and maintenance of blocking and to further raise awareness of its complexity in the more general science community.

More information on the workshop, the detailed program, the keynote speakers, and the organizing and scientific committee can be found on the official Blocking Workshop 2021 website [1].

References:

[1] Official Website of Atmospheric Blocking Workshop 2021: https://blocking-workshop-2021.wavestoweather.de/index.html

[2] Webpage of Atmospheric Blocking Workshop in 2016: http://www.met.reading.ac.uk/~ben/blocking2016/

[3] Waves To Weather: https://www.wavestoweather.de/

Seraphine Hauser, Young Investigator Group: Large-scale Dynamics and Predictability

LINK: https://www.imk-tro.kit.edu/english/7425.php