Changing Weather, Climate, and Drifting Arctic Ocean Sensors

Three people died in Buffalo, New York yesterday shoveling snow that arrived from the Arctic north. The snow was caused by a southward swing of air from the polar vortex that is all wobbly with large meanders extending far south over eastern North-America where I live. Physics deep below the thinly ice-covered Arctic Ocean hold a key on why we experience the Arctic cold from 2000 km north and not the Atlantic warmth from 100 km east.

A wobbly jet stream that separates cold Arctic air from warmer mid-latitude air. Note the strong gradients over eastern North America. [From wxmaps.org]

A wobbly jet stream on Nov.-19, 2014 that separates cold Arctic air from warmer mid-latitude air. Note the strong differences over eastern North America and how balmy Europe, Russia, and Alaska are. [From wxmaps.org]

The Arctic Ocean holds so much heat that it can melt all the ice within days. The heat arrives from the Atlantic Ocean that moves warm water along northern Norway and western Spitsbergen where the ocean is ice-free despite freezing air temperatures even during the months of total darkness during the polar night. As this heat moves counter-clockwise around the Arctic Ocean to the north of Siberia and Alaska, it subducts, that is, it is covered by cold water that floats above the warm Atlantic water.

North-Atlantic Drift Current turning into the Norwegian Current that brigs warm Atlantic waters into the Arctic Ocean to the north of Norway and Spitsbergen. [Credits: Ruther Curry of WHOI and Cecilie Mauritzen of Norwegian] Meteorological Institute]

North-Atlantic Drift Current turning into the Norwegian Current that brigs warm Atlantic waters into the Arctic Ocean to the north of Norway and Spitsbergen. [Credits: Ruther Curry of WHOI and Cecilie Mauritzen of Norwegian] Meteorological Institute]

But wait a minute, how can this be? We all learn in school that warm air rises because it is less dense. We all know that oil floats on water, because it is less dense. Well, the warm Atlantic water is also salty, very salty, while the colder waters that cover it up are fresher, because many larger Siberian rivers enter the Arctic Ocean, ice melted the previous summer, and fresher Pacific waters enter also via Bering Strait. So, the saltier and more dense Atlantic water sinks below the surface and a colder fresher layer of water above it acts as a insolation blanket that limits the amount of ocean heat in contact with the ice above. Without this blanket, there would be no ice in the Arctic Ocean and the climate everywhere on earth would change because the ocean circulation would change also in an ice-free Arctic Ocean, but this is unlikely to happen anytime soon.

A single profile of temperature and salinity from an ice-tethered profile (ITP-74) off Siberia in July 2014. Note the warm Atlantic water below 150 meter depth.

A single profile of temperature and salinity from an ice-tethered profile (ITP-74) off Siberia in July 2014. Note the warm Atlantic water below 150 meter depth.

Some wonderful and new science and engineering gives us a new instant perspective on how temperature and salinity change over the top 700 meters of the Arctic Ocean every 6 hours. Scientists and engineers at the Woods Hole Oceanographic Institution with much support from American tax-payers keep up many buoys that float with the ice, measure the oceans below, and send data back via satellites overhead to be posted for all to see on the internet. Over the last 10 years these buoys provide in stunning detail how the Arctic Ocean has changed at some locations and has been the same at other locations. I used these data in an experimental class for both undergraduate and graduate students to supplement often dry lecture material with more lively and noisy workshops where both I and the students learn in new ways as the data are new … every day.

For well over 50 years the Soviet Union maintained stations on drifting Arctic sea ice that stopped when its empire fell apart in 1991. Russia restarted this program in 2003, but unlike the US-funded automated buoys, the Russian-funded manned stations do not share their data openly. No climate change here …

2 responses to “Changing Weather, Climate, and Drifting Arctic Ocean Sensors

  1. It was always my understanding that the mechanism driving the Planets ocean circulation was the freezing of the surface waters of the Arctic Ocean, where ice forms as less saline ice; driving the circulation via the resulting slightly more saline solution colder water, cooled by the creatioin of the ice above, forming a vast stream, ~200Kms wide, 200 feet deep, that runs down between Iceland and Greenland at ~1.4 metres per sec. If that is correct; at what point does the temperature invert, as that cooler water must have to drive through the warmer mid layer to reach the abyss?

    Looking at the first illustration, it would seem that the warmer water circulation is acting to squeeze the central Arctic Ocean region from each side of the region; forcing the colder air down over the US; in turn creating what seems to be a classic convergence along the US East coast. Here in the UK we seem to have been under such in earlier years, so this event, when repeated, will turn in whatever direction suits. In which case, there must be something else; not described herein; driving the rotation of the squeezed bubble around the globe. Has anyone got an handle on what that mechanism might be?

    Again, if the extended bubble is now to be seen as a permanent feature of the system; has anyone modeled it to see where these events take us in the future? Has anyone created a sequential image showing the movement of the feature for the last five years or so?

    • Chris:

      The wobbly jet stream separating cold from warm air at our mid-latitude is very well predicted in our daily weather forecasts. On TV we only see our own little “local” piece, while I here tried to show this “local” piece as part of a larger global pattern. You can see animations of how the “polar vortex” evolves over time (as it always does) at the web-site

      http://wxmaps.org/pix/NHanim.html

      There are many drivers of the general ocean circulation. Winds, differential heating, density differences, turbulence, waves, as well as ice formation all contribute. I don’t think it is possible to come up with just one mechanism that nails it all down in one swoop. Ice formation is important, but so are the monsoon cycles and the wind-stress curl over the subtropical Pacific and Atlantic Oceans that give us the Kuroshio off Japan and Gulfstream off the USA. On both physical and philosophical levels we are all connected in ways that we do not yet fully understand. There is still much to discover which is very much part of the fun, I feel.

      Andreas

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