Heat Waves


Heat waves have a significant impact on society and the natural ecosystem, as was clearly demonstrated recently by the European and the Russian cases of 2003 and 2010 respectively. They are regarded as extreme weather events and are associated with dynamical processes in the upper troposphere that are not very well understood and downward/upward multi-scale interactions that are hard to predict.

Therefore, the instensity and duration of heat waves pose a challenge for weather forecast models and their impact cannot be assessed several days in advance. In addition, there is increasing scientific evidence that the projected global warming can alter their frequency and intensity.

Mechanisms for the amplification of waves in the upper-troposphere and their connection to boreal summer temperature extremes (with a focus on heat waves) constitute our main reasearch questions. The perspective we follow for the planetary-scale flow is that of localized maxima in Rossby wave amplitudes, or else Rossby wave packets. Apart from the good statistical correlation and the observed coincidence between amplified Rossby wave packets and heat waves, we examine the physical mechanisms behind this link. Multiple interactions, that involve linear or non-linear processes across spatiotemporal scales (from large-scale wave dynamics, to boundary layer effects and land-atmosphere feedbacks) have to be taken into account for a complete investigation of heat waves (and temperature extremes in general).

Temperature anomaly on Aug 8 2003
Hovmoeller diagram of meridional wind (color shades) and Rossby wave packet amplitude (black contours) anomalies during the European heat wave of August 2003.