How extratropical ocean-atmosphere interactions can contribute to the variability of jet streams in the Northern Hemisphere They found that extratropical ocean-atmosphere coupling enhances teleconnection patterns and causes more meandering westerly jet streams, which are linked to extreme weather events.
Ocean-atmosphere coupling is most powerful in the tropics, where the coupling is responsible for the well-known"El Niño-Southern Oscillation" in the equatorial Pacific Ocean. The El Niño-Southern Oscillation, in turn, remotely leads to a meandering jet stream in the mid-latitudes through the formation of large-scale atmospheric circulation patterns, i.e., teleconnection patterns.
To investigate the role of the extratropical ocean-atmosphere coupling, the researchers conducted two simulations: a coupled run, which considered the interaction between the extratropical ocean and the atmosphere, and an uncoupled run, which neglected the interaction between the two components. The simulations examined the impact of ocean-atmosphere coupling on teleconnection patterns during the Northern Hemisphere's wintertime: December to February.
In the coupled run, heat exchange between the ocean and the atmosphere reduced the air-sea thermal difference. As a result, less heat is released from the oceans and into the atmosphere, leading to increased kinetic energy and a more meandering jet stream. Conversely, when the oceans are uncoupled, the sea surface temperature does not respond to atmospheric fluctuations. The larger temperature differences cause more heat to be released, resulting in a less meandering jet stream.
Abrupt shifts of the Southern Hemisphere westerly winds, paced by subtle variations in Earth's orbit, lie at the heart of ice age cycles, according to an international research team. This 'Zealandia ...