Arctic Synoptic Basin-wide Oceanography.

Lead Research Organisation: Scottish Association For Marine Science
Department Name: Scottish Association For Marine Science

Abstract

Look at a map of the world and find the Shetland Islands. Follow the 60 degrees north latitude circle eastwards. You pass through St. Petersburg, the Ural Mountains, Siberia, the Bering Sea, Alaska, northern Canada, the southern tip of Greenland, then back to the Shetlands. All these places are cold, harsh environments, particularly in winter, except the Shetlands, which is wet and windy but quite mild all year. This is because in the UK we benefit from heat brought northwards by the Atlantic Ocean in a current called the Conveyor Belt. This current is driven by surface water being made to sink by the extreme cold in and around the Arctic. It returns southwards through the Atlantic at great depths. Scientists think it is possible that the Conveyor Belt could slow down or stop, and if it did, the UK would get much colder. We know the planet has been warming for the last century or more, and we think this is due to the Greenhouse Effect. Burning fossil fuels puts a lot of carbon dioxide into the atmosphere, which stops heat from leaving the Earth, like the glass in a greenhouse. In a warming world, ice melts faster, and there is a lot of ice on the Earth: ice caps on Greenland and Antarctica, sea ice in the Arctic and Antarctic Oceans, glaciers in high mountains. This causes extra amounts of fresh water to flow into the oceans. Now this fresh water can affect the Conveyor Belt by acting like a lid of water too light to sink, so the Conveyor Belt stops. What is the chance of this happening? We do not know, because there is much we do not understand about how the Arctic Ocean works. You need a powerful icebreaker to get into the Arctic Ocean, and that's only really possible in the summer, because in winter the sea ice thickens and the weather is bad. Scientists all over the world agree that the Arctic Ocean is important because it contains a lot of freshwater, which is why, although it is difficult to make measurements in the Arctic, they have decided to join their efforts during the International Polar Year. Fresh water in the Arctic Ocean is either (nearly) pure fresh water in the form of sea ice, or as diluted sea water in the top 200 metres (roughly) of the ocean. The sea water in the Arctic is diluted because many large rivers flow into it. In Russia, the three largest are the Yenisei, the Lena and the Ob; in Alaska, the MacKenzie; and there are many smaller rivers. Fresh water arrives in the Arctic Ocean from other sources as well: more diluted sea water flows through the Bering Strait, between Russia and Alaska; in summer, ice caps melt a little and some of the melt water runs into the ocean; some of the sea ice melts straight into the ocean; and (of course) it snows. We plan to conduct a set of measurements around the Arctic Ocean, with help from many international partners. We want to know how much fresh water is in the Arctic Ocean now. We will use an ice breaker to enter the Arctic Ocean and will make measurements of water properties. We will also deploy instruments onto the ice cover that will provide data once we've gone and will analyse satellite imagery. All of this data will help us understand the current state of the Arctic Ocean and we will use mathematical models of the ocean, ice cover, and atmosphere to predict conditions before, during, and after the cruise. By measuring small quantities of chemicals dissolved in the ocean waters, we can work out where the ocean water came from. We want to know how this fresh water might travel from the Arctic Ocean southwards into the Atlantic. What route might it take? How does the ocean respond to the atmosphere, to river flows and to sea ice? We aim to answer these questions so that other scientists who try to forecast the Earth's climate in the coming years and decades will know how to represent the Arctic Ocean in their forecast models. And with good forecasts, we can plan for the future.

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