Influence of reduced winter land-sea contrast on the mid-latitude atmospheric circulation
A seminar organised by the geosciences department of the ENS with Alice Portal from the LMD-IPSL on the influence of reduced winter land-sea contrast on the mid-latitude atmospheric circulation.
Long-term projections of the NH winter mid-latitude climate predict a faster warming of the land-surface temperature compared to the sea-surface temperature, hence a reduced winter thermal contrast between the cold continents and the warm oceans. In this work we devise a set of idealised perpetual-winter experiments where the extratropical land-sea contrast (LSC) is strongly reduced in order to detect the mechanisms by which it may influence the mid-latitude circulation. Consistently with previous literature, the results indicate that winter extratropical LSC influences the position and strength of the Atlantic and Pacific jet stream, and the large-scale planetary waves. When we distinguish between Pacific and Atlantic LSC, we find that the former has a stronger impact on the global mid-latitude circulation and that the two have a nearly opposite effect on the strength of the stratospheric polar vortex, itself relevant for the mean state and variability of the mid-latitude troposphere. The results of this idealised study may come useful for extending our understanding of atmospheric-circulation changes in climate projections and of atmospheric variability at interannual time scales.
At the Ecole Normale Supérieure (ENS) : Salle serre – 24 rue Lhomond
Or join with Zoom: https://cnrs.zoom.us/j/94254752722?pwd=YlRXTndHT1oyWDl1NHR3UWtuMC9Bdz09