These giant 'whirlpools', called mesoscale eddies, were previously thought to
"hardly do anything to the climate. Now, for the first time, the amount of water and heat they carry has been measured and it turns out the eddies have a big effect after all."
"It's not clear what this means for the weather, but it is likely to be significant. Some of the world's biggest sources of climate variability, such as the El Niño Southern Oscillation, are powered by heat moving around the oceans, driven by wind and ocean currents. The eddies could have similar effects, says Qiu, and once we understand them it should help us create more accurate predictions of the regional effects of climate change.
"It's also unclear how the eddies will affect weather in the future. It will depend on how climate change affects them, which Qiu says they haven't looked at yet."
Amazing what climate scientists can discover about natural climate change by making measurements and observations instead of assuming what "the consensus" previously believed to be true. The junk output of climate models does not incorporate very important natural phenomena such as these newly discovered large eddies or ocean and atmospheric oscillations, which are the true drivers of weather and climate, not CO2.
Huge ‘whirlpools' in the ocean are driving the weather
11:08 27 June 2014 by Michael Slezak New Scientist
Giant "whirlpools" in the ocean, up to 500 kilometres across, are driving the world's climate on a scale previously unimagined. We just don't know exactly how yet.
The bodies of swirling water, called mesoscale eddies, are 100 km to 500 km in diameter. They form when patches of water are destabilised by obstacles like islands. The eddies carry huge volumes of water and heat across the oceans, until they slowly stop spinning over days or months and reintegrate with the surrounding water.
The assumption was that they gradually diffused the heat they carried in all directions as they travelled, which would hardly do anything to the climate. Now, for the first time, the amount of water and heat they carry has been measured and it turns out the eddies have a big effect after all.
Bo Qiu at the University of Hawaii in Honolulu and colleagues used satellite data from 1992 to 2010 to spot eddies, and floating sensors to map their shapes, volumes and temperatures.
The team found the eddies move as much water as the biggest ocean currents. They mostly move west, driven by the spinning of the Earth. As a result, over 30 million tonnes of water arrive on the east coasts of continents every second.
"The amount of water they can carry westward was a huge surprise," says Qiu.
It's not clear what this means for the weather, but it is likely to be significant. Some of the world's biggest sources of climate variability, such as the El Niño Southern Oscillation, are powered by heat moving around the oceans, driven by wind and ocean currents. The eddies could have similar effects, says Qiu, and once we understand them it should help us create more accurate predictions of the regional effects of climate change.
For instance, eddy-driven currents are probably exacerbating extreme weather around Japan, says Wenju Cai from CSIRO in Melbourne, Australia. Warm water carried by the giant Kuroshio current drives extreme weather, and the eddies carry even more warm water, making the weather worse.
It's also unclear how the eddies will affect weather in the future. It will depend on how climate change affects them, which Qiu says they haven't looked at yet.
It may be that the eddies get bigger and more common in a warmer world. They are the ocean equivalent of storms, and since storms and hurricanes are predicted to become more powerful due to the extra heat energy, the eddies might too. [It may also be that eddies get smaller and less common in a warmer world. Temperature differentials drive all weather, not absolute temperatures, and AGW theory predicts temperature differentials between the poles and equator will decrease. This is why climate models also predict a decrease of cyclones and storm activity over the 21st century:
- New paper projects a decrease of tropical cyclones over the 21st century
- Two new papers predict fewer Northern Hemisphere cyclones in future
- New paper predicts fewer cyclones in North Atlantic & Europe due to climate change
- New paper predicts a decrease in tropical cyclones in the future
- New paper predicts tropical cyclones will decrease 6%-40% over the 21st century
Journal reference: Science, DOI: 10.1126/science.1252418
Oceanic Mass Transport by Mesoscale Eddies
Zhengguang Zhang, Wei Wang, Bo Qiu
1Physical Oceanography Lab, Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, Qingdao, P. R. China.
2Department of Oceanography, University of Hawaii at Manoa, Honolulu, HI, USA
↵*Corresponding author. Physical Oceanography Lab, 5 Yushan Road, Qingdao 266003, P. R. China.
Oceanic transports of heat, salt, and fresh water, dissolved CO2 and other tracers regulate global climate change and distribution of natural marine resources. While the time-mean ocean circulation transports fluid as a conveyor belt, fluid parcels can also be trapped and transported discretely by migrating mesoscale eddies. By combining available satellite altimetry and Argo profiling float data, we show that the eddy-induced zonal mass transport can reach a total meridionally integrated value up to 30-40 Sv (1 Sv = 106 m3 s−1), and it occurs mainly in subtropical regions where the background flows are weak. This transport is comparable in magnitude with that of the large-scale, wind- and thermohaline-driven circulation.
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