Prof. Stéphane Vannitsem 

Royal Meteorological Institute of Belgium

 

邀请人 ： 段晚锁 研究员

 

2024年6月13日（周四）15:00

3号楼二层第四会议室 

 

报告摘要:

Low-frequency variability in the atmosphere at mid-latitudes is covering a wide range of time scales from seasons to millennia. An example of such variability is the North Atlantic Oscillation which reveals predominant weather patterns in the course of the years over the Atlantic and Western Europe. The source of variability is, however, controversial and several possibilities have been envisaged, including coupled ocean-atmosphere variability; stratospheric influence, possibly related to ENSO in the tropical Pacific; and an even more controversial source, namely the solar activity, as discussed in Smith et al (2014). These sources of low-frequency variability (LFV) provide some hope for extended-range forecasts, but a more complete understanding of the impact of these different sources is still missing. The difficulty in understanding and assigning the proper role to the various sources is also due to the difficulties of global climate models to reproduce this natural LFV and the teleconnection patterns it gives rise to, due to substantial model biases. Understanding the role of the ocean on the development of the LFV and of teleconnections is a central topic of current research. 

In the present seminar, we will review our recent works on the analysis of the development of LFV in reduced-order models that we have developed along the years. In particular, we will show how genuinely coupled LFV can emerge in a very simple reduced-order coupled ocean-atmosphere model (Vannitsem, 2015; Vannitsem et al., 2015). We will then discuss the impact of the potential influence of the Tropical Pacific on the extratropics using techniques coming from the theory of Pullback Attractors (Vannitsem et al, 2021). Finally, we will discuss the problem of predictability associated with the presence of initial condition errors in such mid-latitude coupled ocean-atmosphere models, together with the impact of boundary error forcing associated with the influence of the Tropical Pacific (Vannitsem, 2017; Vannitsem, 2023). 

 

报告人简介:

Stéphane Vannitsem is head of the Meteorological and Climatological Information Service of the Royal Meteorological Institute of Belgium. He is also part-time lecturer at the Université Libre de Bruxelles (Belgium) and editor (former executive-editor) of the journal “Nonlinear processes in Geophysics” of the European Geophysical Union. He is currently managing the RMI nodes of several European projects: (i) the postprocessing module of the programme EUMETNET-Weather Forecasting of the European Meteorological Network (EUMETNET) for the period 2024-2028, (ii)  two ITN Marie-Curie projects named CriticalEarth (2021-2024) and EDIPI (2021-2024), and (iii) a JPI-Oceans-Climate project on the interaction between the ocean and the atmosphere (ROADMAP, just ended this year). He is also coordinating several projects at national levels. He published over 100 peer-reviewed publications and an edited book on statistical postprocessing. His main research interest lies in the understanding of (and the development of theories on) the dynamics of the atmosphere and of the climate system, using advanced tools of nonlinear science, in particular based on stochastic processes and chaos theories. Recently, his interest turned on addressing the question of causality in climate dynamics using the Liang-Kleeman theory.