European heatwave in July 2006: Observations and modeling showing how local processes amplify conducive large-scale conditions

International audienceJuly 2006 was particularly warm in Europe. The consistency of this kind of anomaly with large-scale circulation conditions or local processes is a key issue for regional climate evolution. Using observations from space and ground-based observatory, together with simulations from regional model, shows that two concomitant but disconnected drivers explain this heatwave. The first driver corresponds to large-scale conditions (specific atmospheric condition with advection of continental air favoring clear sky). The second condition relates to local processes (dry soil, amplifying surface temperature in heatwave first five days, and making this event warm enough to induce a monthly mean anomaly). This large-scale event is studied at a site in Northern France where comprehensive observation data carefully reanalyzed is available. A regional model is able to produce the amplitude of the event, for both temperature and cloud large-scale anomalies. Coupling model and observations allows discriminating the surface contribution to the temperature anomaly