A new study has provided scientists with a global picture of how ocean activity influences the lower-level atmosphere and vice versa.
Scientists from the University of Maryland used statistical analysis to study the influence of the ocean on the atmosphere in the extratropics, the regions of Earth poleward of the tropics.
The researchers applied a statistical method for establishing causation known as the Granger Method, named after its creator, the Nobel-laureate mathematician Clive Granger.
“There are many physical processes that govern the interaction between the atmosphere and ocean,” lead author Eviatar Bach, a PhD student in the University of Maryland’s Department of Atmospheric and Oceanic Science, told Science Daily. “For example, wind blowing on the ocean surface creates currents, and the sea surface heats up the lower atmosphere. These interactions between the atmosphere and ocean play a major role in climate and our ability to predict it, so understanding their geographical structure is important.”
It has long been known that in the tropics the ocean is the predominant driver of atmospheric changes, while in the extratropics the process works in reverse, with the atmosphere driving the ocean. However, through this study scientists were able to demonstrate the ocean’s influence on climate in the extratropics.
“The most novel finding of this research is that the method of Granger causality found the ocean to influence the atmosphere almost everywhere in the extratropics,” Samantha Wills, a postdoctoral researcher at NOAA’s Pacific Marine Environmental Laboratory, told Science Daily.
“This can be a challenging task given that the atmosphere dominates air-sea interaction in the extratropics, and the influence of the ocean on the atmosphere is not much larger than internal variability,” added Wills, who was not a co-author of the report, which was published in the Journal of Climate.