Title: Impact of diabatic processes across scales

Speaker: Thomas Spengler (University of Bergen)

Time: February 4^th, 9:30 am (Beijing Time)

Location: 13rd floor meeting room, Haozhiying Technology Tower

Contact: Xiaolin Zhang (zhangxiaolin@dlmu.edu.cn)

Meeting ID: 591 502 518

Abstract: The midlatitudes are characterised by baroclinic regions with high occurrence of jet streams and extratropical cyclones, referred to as storm tracks. Despite the progress in reducing storm track biases over the recent decades, current weather and climate models still suffer from significant biases in the representation of zonal asymmetries, latitudinal positioning, and overall intensity of these features. Given that diabatic processes significantly influence the evolution of storms, it is not surprising that the inadequate representation of moist processes on smaller scales has been identified as a potential key source for these biases. Yet, we still lack a fundamental understanding of the role of moist diabatic processes on storm tracks and jet dynamics.

We will present recent advances in our understanding of how diabatic processes influence the evolution of both storms and the baroclinic zone in the midlatitudes. The impact of diabatic processes is shown to significantly contribute to pulsations in the storm track, which are often associated with clusters of cyclones and extremes. Furthermore, I will elucidate how synoptic jet streams are intensified by diabatic heating, while the commonly accepted time-zonal-mean paradigm indicates a detrimental effect of diabatic heating on jet stream strength. These conflicting views demand a revised dynamical understanding reconciling these contradicting views to bridge between synoptic and climate perspectives.

Bio:

Thomas Spengler is a meteorologist focusing on the combination of theory, observations, and modelling, specialising on scales ranging from meso and synoptic to large-scales. From 2015-2024 he was the director of the Norwegian Research School on Changing Climates in the Coupled Earth System (CHESS). He is currently leading research projects focusing on atmosphere-ocean-ice interactions at higher latitudes as well as air-sea interactions and cyclone development in the midlatitude storm tracks. In 2012 he was elected into the International Commission for Dynamic Meteorology (ICDM) and has been elected President of ICDM since 2019. Since 2022 he is the elected Leader of the Norwegian Geophysical Society. He was awarded the prize for best lecturer of the academic year 2012/2013 at the Faculty for Mathematics and Natural Sciences at the University of Bergen and nominated for the IAMAS early career scientist medal in 2013. He lead a science outreach project together with the Bergen Philharmonic Orchestra, featuring four concerts with themes on Space, Ocean, Climate, and Humankind. He is a member of the Scientific Advisory Committee for the European Centre for Medium-Range Weather Forecasts as well as a member of the Mission Advisory Group for the European Space Agency Earth Explorer 11 mission WIVERN.