Friday, January 15, 2016

A message from the abyss

Float #9749, the first SOCCOM float launched from the RV Investigator (yes!, the one that carries Jose' as name :-) ) has spoken!! The first profiles have been sent via satellite to the Monterey Bay Aquarium Research Institute (MBARI) lab, where they have been interpreted and plotted. And here is what they look like:


The plot shows depth profiles (depth is on the x-axis) of pH, oxygen, temperature and nitrate. Look at that peak in oxygen (red curve) at about 100 m: that's due to phytoplankton using CO2 and releasing oxygen. pH is also indicative of the biological activity. Temperature and high values of oxygen in the first 400 m are indication of a water mass called "Mode Water". While below that depth, we have the Antarctic Intermediate Water, with a minimum in oxygen. 

What an exciting moment!! Yesterday I received this plot on my email and I almost (well.. I actually did) screamed for joy! :-). I was so nervous, waiting for the first sign from the float. "What if the sensors did not work? What if the float has hit something?".. that kind of stress. You feel responsible, you have a mission to accomplish, that you've been planning long in advance.. everything must be perfect! We want data, we need them. We wanna know what's happening below the surface of the ocean, understand what the occurring physical, biological and chemical mechanisms are, how the oceans are changing. Especially here, in the Southern Ocean. Due to many reasons (one for sure is the brutality of the weather and ocean conditions, that make any operation very very difficult), observations have been minimal here compared to other parts in the world. But we are getting more and more of them, as the scientific community has recognised the importance of the Southern Ocean for the whole climate system.

What's so special about the Southern Ocean? This ocean, located south of, let's say 30 deg S, connects the Indian, Pacific and Atlantic oceans, stirring their waters and mixing their properties. It also serves as link between the surface and deep waters (note that, the circulation of the oceans around the globe is very complicated: waters that flow at the surface can sink in different locations, which are then transported at depth to different parts of the world and finally rise again to the surface, somewhere else.. after a time scale of up to thousand years!). While transporting waters up and down in the water column, different dissolved gases are exchanged and transported too. For example, in the Southern Ocean there are places where the water sinks and, by doing so, transports down to depth the atmospheric gases that the ocean has been in contact with, through the ocean surface. For example, carbon dioxide. But there are other locations where the waters are upwelled, and those dissolved gases brought back to the atmosphere. Recent studies found that, of the total amount of carbon dioxide due to human activity absorbed by the global oceans since 1750, the Southern Ocean alone may have absorbed up to a half. Carbon dioxide can enter the ocean also via another process, which is due to the enhanced solubility of carbon dioxide in cold water, rather than warm: so, surface waters flowing towards Antarctica get colder and uptake carbon dioxide; while waters going towards the warmer tropical waters release it. We also need to add the role of biology in the Southern Ocean, which I talked about in a previous post, to this picture, as it's a fundamental process in the uptake of carbon dioxide. Adding carbon dioxide into the ocean cools the atmosphere, while releasing it into the atmosphere warms up our climate. So, to wrap it up, because of the physical circulation, the biological activity and the solubility in the Southern Ocean, it comes that this ocean has a pivotal role in the climate system. Any changes to either the physical or the biological or the chemical world in the Southern Ocean can have a dramatic impact in the global climate system. 

That's why it's so important to improve our knowledge of the Southern Ocean!

I have other 6 floats to deploy on this voyage and the next one will soon be prepared, as it will be launched 24 hours from now! Fantastic!! The weather has also been nicer today and someone spotted some pilot whales (I was at the gym, so no whales for me :-( ). Tomorrow is gonna be very intense, as we'll have many many activities to do (I'll show you in few days what we've been up to). But, before that, I gotta prepare my talk for tomorrow! Talks on a ship are a really good way to get to know each other's interests and learn something new.. For example, do you know that if a ship sails over a gas leak, because the ship becomes less buoyant than the surrounding water, the ship could sink? That makes me think.. We are looking for an underwater volcanic field.. which releases gas. uhm… just saying… O.o 


No comments:

Post a Comment