Australia: The Land Where Time Began

A biography of the Australian continent 

Southern Ocean Eddies Imprint on Winds, Clouds and Rainfall

Mesoscale eddies are omnipresent because of the turbulent nature of the ocean, but the impact these transitory, approximately circular temperature fronts in the surface waters of the ocean have on the atmosphere above them is not well known. It has been reported that stationary fronts, such as the Gulf Stream, lead to pronounced changes to the atmosphere (1,2), though it has not been determined systematically what the impact of transient ocean eddies on the atmosphere is, apart from winds, and clouds to some extent (3-6). In this paper the authors examine what the atmospheric conditions are that are associated with more than 600,000 individual eddies in the Southern Ocean by the use of satellite data. Their results show that near-surface wind, the properties of clouds and rainfall are all locally affected by ocean eddies. According to the authors¹ the pattern of atmospheric change that is observed is consistent with a mechanism in which the atmospheric boundary layer turbulence is modified by sea surface temperature anomalies associated with oceanic eddies. In cases involving cyclonic eddies near surface winds are caused to slacken by this modification, and the cloud fraction and water content declines, and rainfall is reduced. It was concluded by the authors¹ that much larger atmospheric low-pressure systems that pass rapidly by at the latitudes the authors¹ were studying can be affected significantly by these transient mesoscale ocean structures.

Sources & Further reading

Frenger, I., N. Gruber, R. Knutti, and M. Munnich. "Imprint of Southern Ocean Eddies on Winds, Clouds and Rainfall." Nature Geosci 6, no. 8 (08//print 2013): 608-12.