zum Thema: Impact of the Gulf Stream on the North Atlantic climate variability: new insights
Zeit: Montag, 3. November 2014, 12:00 Uhr (s.t.)
Ort: SR des Wegener Center im 1. Stock, Brandhofgasse 5
Moderation: Dr. Heimo Truhetz
Herzlich willkommen!
Abstract:
The coupled atmosphere-ocean system has been studied for a
long time by the climate community. In the last decade, high resolution
satellite observations and numerical simulations have brought new
insights by highlighting the unsuspected importance of mechanisms
related to sea surface temperature (SST) fronts. The classical basinscale
paradigm is that the SST is mostly passively driven by surface
winds through turbulent heat fluxes at mid-latitudes. However, there is
now compelling evidence that sharp SST gradients, as in western
boundary currents, drive wind convergence at surface that can create
deep vertical motion into the free troposphere.
Over the Gulf Stream, intense moisture and heat fluxes occur at the airsea
interface and are responsible for large energetics exchanges
between ocean and atmosphere. During my PhD I used a set of highresolution
(approx. 50 km at mid-latitudes) global atmospheric and
coupled simulations to study the sensitivity of the North Atlantic climate
variability to the spatial resolution of the Gulf Stream SST front.
In the first part of this presentation, I will review some recent studies on
the small-scale air-sea interaction at mid-latitudes. Then I will present
new insights on the mechanisms involved in the atmospheric boundary
layer response to the Gulf Stream SST front and how significant changes
in the extra-tropical storm track are induced over the North Atlantic and
Europe during winter. Finally, the effects of the atmospheric feedbacks
onto the ocean will be discussed in the context of fully coupled
simulations.