The Southern Oceans, Widnes SciBar 11th February 2015

The challenge of observing the deep ocean: who cares and why is it so difficult?

Dr Matt Donnelly, British Oceanonographic Data Centre (BODC)

On the 11th February, we welcomed Matt Donnelly a data scientist who works at the British Oceanographic Data Centre who outlined the key physical characteristics of the oceans:

• water density, largely determined by temperature and salt content,
• wind patterns at different latitudes that cause ocean currents,
• temperature,
• current speed and direction.

The Southern Oceans

These are significant features of the Thermohaline Circulation (thermo - heat; haline - salt). With a transit time of around 1000 years, currents cause an extensive mixing between the ocean basins, reducing differences between them and making the Earth's oceans a global system. On their journey, the currents transport both energy (in the form of heat) and matter (solids, dissolved substances and gases) around the globe. Such circulation has a large impact on the climate of the Earth.

Southern Ocean Matt’s particular interest is in the Southern Ocean, the only ocean that stretches all around the globe, linking the Atlantic, Pacific and Indian Oceans. Unlike other oceans there is no north / south barrier to current flow; as a result, there is a current around the Antarctic continent (the Antarctic Circumpolar Current) that carries more water than any other current in the world. The sea water can be cooled to near freezing at -1.8°C and become highly saline - as a result it sinks to the ocean floor and spreads out over the global oceans as part of the Thermohaline Circulation. Using food dyes Matt demonstrated the how pure water, slightly saline water and highly saline water when introduced into a tank do not readily mix, with the highly saline layer being at the bottom.

Impact of Oceans on Climate The oceans are a massive heat store - the top 5m of oceans have the same heat capacity as the entire atmosphere above them. The ocean currents move cold and warm water around the globe. Heat and moisture are exchanged between the atmosphere and the ocean, effectively acting as one. Climate change theorists had predicted a steady increase in the average temperature across the world. However, for the last 10 years or more this increase hasn’t been as significant, as observed by the conventional methods of measurement - as the heat input continues, where is it going?  One possible explanation is that the heat added by human activity has been absorbed by the oceans and distributed by ocean currents.

Gathering Information about the Oceans Matt described several methods of making measurement - here are a selection.

Ships. Dedicated research ships are the traditional way of studying the oceans & one experienced by Matt in the Southern Ocean. However, this is an expensive way of gathering information and is limited to the route that the ship takes. XBTs (Expendable Bathythermographs) can be dropped from ships not specialising in research (e.g. cargo ships); as it sinks the measurement probe sends data to the ship by wire until  the wire runs out and breaks, and the XBT then sinks to the ocean floor. Seal Tags. A measurement device & transmitter are glued to the rear of a seals head and measurements are received according to the route & depth the seal takes. When the seal moults, the device is lost. Matt showed the trail a seal took circumventing the Antarctic continent.

International Argo project. Matt described this as ‘a game changer’. With international collaboration, large numbers of Argo floats which have controllable buoyancy are dropped into the sea where they are moved by the ocean currents. Powered by batteries, they are programmed to:-

- sink to a specified depth to gather information, e.g. salinity, temperature,

- float with the current for a specified period, still gathering data

- return to the surface and transmit the data they have collected to a satellite,

- repeat this cycle until the battery is exhausted, usually after about 4 years. 

Matt said there are currently 3290 floats in operation, one of which has been operating for 8 years. In his role as a data scientist, he is involved in making use of the vast amount of data received (e.g. reports from 300 floats a day). Part of the international agreement is that the data are freely available to everyone, without restrictions.

Future Methods of Measurement. The Argo floats currently in use are limited to a depth of 1000m. The floats typically park there for ~9 days, descend to 2000m, then record a profile on the way to the surface.  Matt's role is to help ensure access to the data is maintained at all times for the scientific community. However, as the current Argo floats can only reach less than half the average depth of the oceans, the next stage is to deploy floats able to cope with the high pressure of 6km down - little is known about the oceans at such depths. One possible explanation of why the world average temperature has not increased in recent years is that the excess heat has been taken up in the deeper ocean water.

British Oceanographic Data Centre The BODC is a national facility for looking after and distributing data concerning the marine environment. It is hosted by the National Oceanography Centre, at its Joseph Proudman site in Liverpool.

Joseph Proudman.  Joseph Proudman (1888 - 1975) was ‘a distinguished British mathematician and oceanographer of international repute. His theoretical studies into the oceanic tides not only "solved practically all the remaining tidal problems which are soluble within the framework of classical hydrodynamics and analytical mathematics" but laid the basis of tidal prediction service (developed with A. T. Doodson) of great international importance’(Wikipedia). Incidentally, in his pre-university days Joseph lived in Bold and was a teaching assistant at Farnworth, both only a short distance from the Hillcrest Hotel where the SciBar meets. (We'll add a photo of the grammar school when we establish the date!)

Thanks to Matt for a very interesting and enjoyable evening.

Bob Roach

24th Feb 2015 (modified 8th March 2015)

Teaching seminar etiquette as well as presentation skills

I went to my first academic seminar in 1980, since then I have been to one a week on average, which means I have sat through over 15 000 seminars! In fact I haven't included scientific meetings, so I reckon 20 000. It seems a high number, but I reckon many of my colleagues are veterans of many more seminars. Some have been more memorable than others, but I have no doubt that seminars and presentations have shaped my views on Science in a profound way. Hearing Fred Sanger (top left) explain the principles of DNA sequencing of the lambda genome in the early '80s, was a privilege, if not the most inspirational of talks. Being enthralled by Sydney Brenner with his two overhead presentation of the wider implications of puffer fish genomics in a filled lecture theatre where you could hear a pin drop. These are memories that will (hopefully) stay with me. Then there were the seminars that irritated, frustrated, infuriated me, or just simply sent me drifting into a daydream. The truth is presentations and their style and content combined with the personality in front of you is not always perfect. However, I have witnessed Kim Nasmyth stand up at a meeting in Oxford (I think) in the early 1980s and deliver an impromptu chalk and talk presentation on the molecular biology of mating type switching in yeast, "about the time the slide projector broke" (to steal from Bob Dylan). It was stunning, and at the time, I was deep into the steady state kinetics of enzymes! (It's true!) This also make a point that some of my most memorable seminar experiences  have been on topics I would not have thought (in a million years) would be of any interest! In fact I have a rule of thumb for seminar attendance that says: "Dull title:must go"!

So seminars have stimulated, irritated, informed and entertained me over many years. I really can't get enough of seminars. I have already written about the value of seminars in an earlier Blog, but here I want to discuss the importance of the audience, the listener and the chairperson or facilitator. Just consider a presentation from a visiting speaker to a mixed audience. Let's say the topic is "Behaviour and Patterning in East Asian Lepidoptera" (just in case, butterflies and moths). The audience comprises students, academics, interested enthusiast and the age range is 14 to 84. The speaker, Professor Linnaeus has travelled by car from a  University seventy miles away, and the seminar is scheduled for 4.30pm. It's November and it's cold and wet! The audience begins drifting in ten minutes early and by 4.35, the chairperson introduces the speaker, a few words of background and a general welcome. Three more people drift in and the speaker overcomes the challenges of lap-top and projector incompatibility and dims the lights to maximise the impact of his slideshow. The pressure is now on the speaker to deliver an engaging presentation, legible slides, attractive images, a logical flow, evidence-based information and sometimes a little speculation to stimulate discussion. The closing minutes are devoted to acknowledgements: the support of colleagues and funding bodies and, where appropriate, a mention of any commercial interests.

Now it is the turn of the audience to play their role in the seminar. Some are there to listen and expand their awareness of a topic they may be largely unfamiliar with: such participants may often ask for clarification, which in turn may help the understanding of others. Some will be experts, looking for insight that they may have missed, or they may be more predatory; challenging the speaker's confidence in a controversial view or data that may have alternative interpretations. The widely held view is that scientific seminars should promote exchange of ideas and that personal rivalries or grudges have no place in the lecture theatre. Of course, we do not live in an ideal world, and the best laid plans can go astray! However, it is the responsibility of the Chair to manage the transition from presentation to discussion and on to closure, or to welcome the next speaker. An experienced session chair should stimulate discussion, if the speaker has failed, or the audience are silent. Seminar etiquette is such that an audience should show engagement with the speaker and the presentation by asking one or two questions. However, it is also important in situations where several speakers are presenting, that the chair keeps the speakers and the audience in check to ensure speakers have approximately equal time to present. 

What is not acceptable is audience hectoring, where one or more individuals take against the speaker and repeatedly challenge a point, or in some cases take the discussion away from the main theme, in order to "steal the show". Here, whilst some speakers are able to "handle" such heckling, sometimes the chair has to intervene, but if this fails, the audience must make it clear that such outbursts are inappropriate and that (especially personal) disagreements should be taken "offline".

In conclusion, seminars from visiting speakers or at scientific symposia are a two way event and both speaker, audience (and chair) need to understand the rules of engagement! I feel that audiences should, on the one hand, be less passive in scientific seminars, but on the other, they should always be courteous, and should choose the most appropriate way of challenging a speaker. This will sometimes be during a talk, after a talk or sometimes in private. However, I do get irritated when audience members walk off down a corridor mumbling to colleagues that "Who on earth funded that project", or the evidence for that particular conclusion doesn't take into account any of my last two papers! So maybe we need to teach students how to participate in seminars, not just how to present one!