What am I doing here anyway?
In short, I found out in 2011 that the water amount in the Arctic Ocean goes up and down a lot and quite rapidly – read below to learn what I mean by “a lot” and “quite rapidly”. Now I am back in the area to find out what exactly happens with the water coming in and out, specifically how cold and fresh the water coming out is. All this matters because the amount of volume, salt and temperature of the water entering and exiting the Arctic strongly affects sea ice thickness, and sea ice extent, nutrients distribution, ecosystems, ocean circulation and climate.
Let me explain with a little more detail…
Fram Strait is the deepest of the gateways that connect the Arctic ocean with lower latitude oceans. I made the map above to guide you through this post. The map shows the ocean’s depth in the vicinity of Greenland, Norway, Iceland, and of part of the Arctic Ocean proper. It also shows where Tromsø (in the main-land of Norway) and Longyearbyen (in Svalbard archipelago of Norway) are: the two primary locations during my stay in Norway. Fram Strait is right between Svalbard and northeast Greenland.
Generally, the warm and salty water from the North Atlantic enters the Arctic Ocean partly through the Barents Sea Opening (which is between Norway mainland and Svalbard), but most of it continues its way north to enter through Fram Strait. This warm and salty water (shown in orange arrows on the map) enters on the eastern side of Fram Strait and most of it continues to circulate around the Arctic Ocean, while a relatively small part of it recirculates right in the strait to return back south (which I call RAC, or Recirculating Atlantic Water in the map). On the western side of Fram Strait, we have cold and fresh water (shown in blue arrows) that exits the Arctic flowing southward into the North Atlantic.
Now, we would expect the volume of water entering the Arctic to mostly balance the volume exiting the Arctic, at least over time. But this equilibrium is not perfectly reached: sometimes there is more volume of water inside the Arctic, and sometimes there is less volume of water, relative to some time-average. Overall, there is a lot of variability in the amount of water in the Arctic Ocean, and this is true whether we think of timescales of days, months, years or decades. As part of my doctoral work, I found that about every 15-25 days, the amount of water in the Arctic changes a lot too. I found this by looking at data from bottom pressure sensors that my PhD advisor (Jamie Morison) and I installed. We collected data for 10 years (see the map for location). Bottom pressure sensors provide data of the variability in ocean mass or ocean weight – basically, at relatively short timescales (few days to few months), the changes in ocean weight in polar regions are equal to changes in ocean volume or sea level. Looking at similar data available from other locations inside the Arctic, I found that the variability of volume shown by my pressure sensors was also consistent with the variability observed in all other pressure sensors, and that these changes in volume were driven by the winds blowing between Greenland and Norway. So the whole volume of the Arctic goes up and down in less than a month because of the wind. This work was published in 2011 (click here to find the details, or please contact me and I will happily send you a PDF version of it).
Alright – but what happens with all this water going in and out very “rapidly”? When Arctic ocean volume or sea level goes up, it mostly brings up a lot of warm/salty water from the Atlantic. When it goes down, however, is it flushing out only colder and fresher water from the Arctic? Or is it flushing out mostly Atlantic water as part of the “recirculating water” shown in the map? This is what I am going to find out, using the observations that researchers at the Norwegian Polar Institute (NPI) have been taking in western Fram Strait since the 1990s (locations of NPI bottom-moored instruments are shown in the map), in combination with my eastern Fram Strait (green x in the map) and North Pole (purple x in the map) pressure sensor data.
In addition to this work, I will do a couple of 5-day trips to Longyearbyen, Svalbard, during which, hosted by Dr. Frank Nilsen, and in collaboration with other UNIS (University Centre in Svalbard) colleagues, I will contribute to the analysis of the in situ ocean bottom pressure records obtained by the UNIS team as part of their Remote Sensing of Ocean Circulation and Environmental Mass Change (REOCIRC) program. The REOCIRC program aims to track changes in the circulation of both the warm and salty West Spitsbergen Current entering the Arctic, and the cold and fresh Coastal Current (purple arrow in the map), also flowing northward but on the continental shelf west of Svalbard. I will combine satellite observations of ocean bottom pressure from GRACE (Gravity Recovery and Climate Experiment) with data from the REOCIRC program to try to isolate ocean vs glacier signals in Western Svalbard. I bring my over 10-year of experience in using GRACE data to UNIS, and I am confident our collaboration will bring exciting results.