The most fun you can have with 31 small pieces of paper?

Every week this term I am taking a couple of one hour sessions with first year students that are designed to improve their understanding of basic statistical concepts – you might know this already because you might be one of those students (or you might be saying to yourself  “so that’s what it’s all about”). This week’s session (Number 5 in a series of 9) is all about exploring the difference between population statistics (i.e. statistics obtained when the whole population has been measured – such as the mean height of all students at the university) and sample statistics (statistics obtained when it is only possible or practical to measure a subset of the whole population – such as the mean height of 100 randomly chosen students at the university). Usually it is only possible to measure sample statistics but what we really want to know are the corresponding population statistics.

So, the session involved taking an entire  population of measurements (the 31 maximum daily August temperatures in Plymouth in 2003 as it happens) and calculating the mean and standard deviation for this population. Then small samples of varying size (2, 4, 8 and 16 values) were selected randomly from the population and the sample mean and standard deviation for the sample were calculated in each case. When you do this lots of times you find that the statistics obtained with the small sample sizes vary a lot and can be a long way off the population statistics but when the sample sizes are larger there is less variation and the values are close to the population values (which is a fairly obvious result but still a nice one to demonstrate). Anyway, the fun part revolved around how the students obtained their random samples from the population. To do this I gave small groups of students a strip of printed numbers (1 through to 31) which they ripped up into 31 small pieces of paper (each with one number on) then folded (to obscure the numbers) and then randomly picked however many numbers they needed. It is such a simple process but at the end of a busy day (for them) it was a joy to watch them all merrily ripping up their paper strips, mixing up the numbers, drawing them out and then doing the calculations. They were smiling and laughing and joking when they messed things up and I was instantly struck by the thought that this must undoubtedly be the most fun you can have with 31 small pieces of paper. Unless that is, you know otherwise…

Ocean Gliders

Way back when I was a PhD student one of the big fusses in oceanographic circles was an autonomous instrument platform that was under development called Autosub. Autosub is a fairly large autonomous submarine capable of powering its way through the oceans whilst carrying a payload of oceanographic instrumentation. Everyone was excited about the possibilities that Autosub would provide but it was some time before the plans came fully to fruition (the first science missions were carried out in 1998).

Without wishing to do anyone a dis-service, the story that I heard was that the original calculations of the weight of the required battery packs were wrong and so when the first attempts to build Autosub took place it was impossible to get the whole package to float… only when battery technology had advanced several steps was Autosub able to get back on track. I’ve no idea whether this story is true, but if it isn’t it should be because it is a much better excuse than simply saying that these things take time. Anyway, following six science mission campaigns funded by the Natural Environmental Research Council, Autosub moved onto its full-on wow-factor missions, Autosub-Under-Ice although an Autosub did become trapped beneath Antarctica on only its second mission under ice mission. There is a BBC Radio 4 “The Material World” programme on Autosub that was broadcast just before this incident.

More recently, there have been a number of other developments using autonomous underwater vehicles to measure oceanographic parameters. One such involves a trio of robot gliders that are being used to profile the top 1000m of the Atlantic Ocean between the Canary Islands and west Africa. The measurements are being made as part of the Rapid-WATCH programme (Rapid Climate Change – Will the Atlantic Thermohaline Circulation Halt?) and help to fill gaps in data coverage that resulted from traditional moorings being damaged by trawlers. The gliders, which are under 2m long use a pair of floatation bladders within which oil is pumped to vary the buoyancy and thus cause upward or downward movement of the glider. There are also now plans to use the gliders in the waters off Antarctica and also for a new generation of gliders, so it seems as though the early work, and the excitement this generated back in the late 1980s and early 1990s is finally paying off. There is a New Scientist article (Issue 2684, 29 November 2009) on the gliders being used within the Rapid-WATCH programme.

Energy from the depths

When I started my career as a lecturer in Ocean Science way back in 1993 one of the topics that students often wanted to research for their final year project was Ocean Thermal Energy Conversion (OTEC). This is the name give to the potential to utilise the routine difference in temperature between warm surface ocean waters and the colder water found at depth. The basic idea is to use the warm surface water to heat a specially selected low boiling point fluid (such as ammonia) until it boils and then use the resulting high pressure gas to drive a turbine to generate electric power. The gas is then cooled using cold water pumped up from the deep ocean (at least one kilometre down) to turn it back into a liquid before repeating the whole process all over again (and again, and again…). The principal barriers to generating power in this way are the enormous technical difficulties involved in pumping the cold water up to the surface, building a robust and stable platform to complete the whole process at sea and transmitting the power from the point of generation to the point of use. After a few years in my job OTEC seemed to disappear off the radar as oil prices fell and I haven’t encountered it for 15 years or so. It was interesting then, to read a recent article in New Scientist about the latest attempts to use OTEC. These are based around US military bases in Hawaii and Diego Garcia along with several pilot projects in the far east (e.g. India and Indonesia). The technology still has a long way to go before it realises the kind of potential that its proponents claim it has, but the threat of rising oil prices and a drive for energy independence seems likely to sustain recent interest in OTEC over the coming years. The full New Scientist article appeared in Issue 2683 (22 November 2008).

Snow? What snow?

So is the city of Plymouth sitting inside a sealed bubble, cut-off from the rest of the world, or what? Once again I have woken up to reports of huge (for the southern part of the UK) snowfalls, with the area just north and east of Plymouth being particularly badly hit. Last night, hundreds of motorists were trapped on Haldon Hill just west of Exeter and other routes across and into the south-west are also closed. Walking into work I have seen parked cars with a few centimetres of snow perched incongruously on the roof and I can go online (here for example) and see photographic proof that there really is snow and disruption out there.

But what of Plymouth? Can I see a single flake of snow in the sky? Can I see a single flake of snow on the ground? The short answer is “no”. Whilst the rest of the country has being struggling away with people grumbling about our inability to cope with the extreme weather, Plymouth has just carried on with no snow, no days off school for children,  no snowmen, no snowball fights. It’s actually hard to believe the news reports and hard not to feel that we’re living in a bubble here.

BBC Radio 4 – The Material World

As a child I grew up in a BBC Radio 4 household. People who know me well might say that this explains a lot, certainly it is probably responsible for the way I talk… Nowadays, with a busy life and a home life that seems to generally involve people rushing about here and there, I never seem to find the time to listen to Radio 4 and this is something that I often wish was not the case because Radio 4 is the home of a huge amount of interesting, funny and informative material. One particularly good programme is “The Material World”, a weekly half-hour offering on science. The format is generally the same – there are two items each getting roughly half of the air-time during which the presenter, usually Quentin Cooper, talks to one or more scientists, engineers or similar beings about a topical issue or piece of work.

Fortunately for people like me who never manage to listen to the radio at home, “The Material World” has its own web-page from which it is possible to listen online to past episodes. It is also possible to download episodes as podcasts (e.g. via iTunes). This is great because not only can you listen to past episodes that look interesting, but you can do so whenever you want! Now that I have set this web-site up I will write about episodes that I think are of particular relevance to oceanography and meteorology as and when they occur, but to start things off I thought I would provide a list of some of the past episodes that I might have included in this way if this site was already up and running. I don’ty pretend to have listened to all of these but they are all episodes that judging by the blurb should be of interest to anyone interested in marine and atmsopheric science. Please be aware that each time you click on one of the links the page for that episode will open in a new window. You can then listen to the episode by clicking on the Listen Again link provided. If any of the links are incorrect or broken please let me know so that I can correct or remove them.

From 2005: air pollution – trees and climate change – coastal wind jets

From 2006: ghost ship – Thames barrier – artifical gills – deep sea fish – gas hydrates – mega plumes – forecasting evolving coastlines(1) – Antarctic Science – solar energy – stratospheric broadband – a new look at the sun – sediment analysis and charting the ocean’s organisms – data logging animals

From 2007: the Thames whale – Scapa Flow – international polar year – El Nino – managing uncertainty in complex models – flood warning – seaside bouquet – Sumatran earthquakes – Arctic sea ice – fish stock extinction – algae(2)

From 2008: deep tropical ocean kelvin waves(3) – plate tectonics – Severn barrage – predicting natural disasters – seaweed and iodine – ocean acidification(4) – the secret seeds of clouds – subglacial lakes – seawater greenhouses – lobster hotels – the deep carbon cycle

(1) featuring my PhD supervisor Professor Alan Davies from Bangor University
(2) featuring Professor Peter Liss from the University of East Anglia, former President and current fellow-Council member of the Challenger Society for Marine Science
(3) featuring Professor Karen Heywood from the University of East Anglia, a postdoctoral researcher at Bangor University when I was taking my MSc and PhD there
(4) featuring Dr Jason Hall-Spencer from the University of Plymouth

CO2 rising

On my walk into work this morning I listened to last week’s Scientific American podcast (something that I thoroughly recommend to anyone who has a general interest in science). The bulk of the episode comprised an interview with Tyler Volk  from New York University discussing his recently published book called “CO2 Rising: The World’s Greatest Environmental Challenge”. The interview provides a useful introduction to the problems posed by increasing levels of carbon dioxide on Earth and the book is certainly one that I will put on my list of future reads (at present it is only available in hardback, published by MIT Press). One of the things he does in the book is to track various carbon molecules on their different routes around the Earth’s carbon cycle , giving each molecule a name and a personality. That might sound a bit “cheesy” but judging from the interview it probably works.

Google Oceans

Google Earth has been around a few years now and many people are familiar with it as a tool that “lets you fly anywhere on Earth to view satellite imagery, maps, terrain, 3D buildings, from galaxies in outer space to the canyons of the ocean. You can explore rich geographical content, save your toured places, and share with others” (Google Earth website). Now Google Earth has been upgraded to allow users to view large parts of the ocean floor. Given that oceans cover over 70% of the Earth’s surface, the existing Google Earth had to be upgraded at some point but the addition of ocean seafloor has meant a change from the satellite sensors used to provide mapping information for the land surface to the acoustic sensors that are used by marine surveyors to map the seafloor. Much of the seafloor data has come from the US Navy and this means that there are blank regions in sensitive areas. Google Oceans can be obtained by downloading (for free) the latest version of Google Earth. You can read more about this new facility on the BBC website and at New Scientist magazine.

Collapse

Well, it took me the best part of a month and in the end I was quite relieved to get to the end but I have just finished reading an excellent book called “Collapse: How Societies Choose to Fail or Survive” by Jared Diamond (Penguin Books website entry). It presents detailed analysis of the probable reasons why past human societies such as Easter Island, the Greenland Norse and the Mayans collapsed, considers collapsed or collapsing modern societies such as Rwanda and Haiti and then examines what these collapses can tell us about the possible future of present societies. It considers the problems facing societies such as modern-day Australia and China and examines the way that our continuing, non-sustainable use of the Earth’s resources, population growth and globalisation impact on the future prospects for human civilisation. It is a huge book with many interesting and challenging components but also one of those books that becomes something of a blur by the time you have finished it. However, I certainly found that it challenged the way that I think about our future and reminded me that significant changes will occur in my lifetime and will impact dramatically on the world that my children will live in as adults. It is not a book that offers no hope, in fact it is one that helped to re-energise me to continue with the small changes that I am making in my own life that may help in some small way to preserve future human societies.

Mamma Mia! What an experience…

I think I should start this entry by making the statement that I am a 43 year old man with an all female family – one wife and two daughters – it’s quite important that I get this point straight at the outset.

On Christmas Day our family acquired DVDs of various films. Since then, we have been working our way through the titles and, so far, we have watched four titles together. This probably sounds innocuous enough, but let me tell you the titles of the films first before you make a judgement  – in watched order:

  1. Angus, Thongs and Perfect Snogging
  2. Wild Child
  3. Mamma Mia!
  4. The Bee Movie

The first two titles were the selections of my daughters who had seen both films in the cinema with my wife a few months ago. They were adamant that I would hate them because they are basically films about teenage girls having crushes on teenage boys or running wild at boarding school. Consequently, there was much merriment at home as we settled down to watch the films and there were lots of sideways glances at me to try to gauge my reaction. The third title was a big favourite of my wife when it came out in the cinema and had been viewed at least once by everyone else in the family on the big screen but which I had somehow avoided at the time. Still, as the fastest selling DVD of all time (apparently) it is obviously a much loved viewing experience for many people. I was told that the film “would make me want to go on holiday to Greece” (where it is set), “would bring a smile to my face”, “would make me feel good” etc. The fourth title is an animation based around the premise that bees are being ripped off by humans, with the latter taking the bee-manufactured resource (honey) without compensating the bees for their hard-work. The main bee character talks, and falls in love with, to a human woman and leads a successful legal case against the major honey companies but the result is that the bees are then all put out of work, there is no pollination of plants and flowers and everything starts to die. Fortunately, it is realised just in time what is happening and the bess fly to the rescue and save the world. Wow.

So what did I think. Well, The Bee Movie was good in an “another clever animated film even it is rather contrived” kind of way but I have to say that apart from “Soccer Dog”, “Mamma Mia” was probably the worst film I have ever seen. My words at the end when asked what I thought were ” It was an experience” (with an accompanying muttered “dreadful” and private and prolonged shake of the head). Actually “Soccer Dog” (which is about a dog belonging to an american boy that joins a boy’s football team in Scotland and helps them beat an all-star team of professionals in a specially arranged match) was rather good fun because it was so bad that it was good (you can see the string that controls the ball in some of the action shots…). But “Mamma Mia”…? Truly dreadful, with almost no redeeming features. Even “Wild Child” had its merits – a plot and some dialogue for example. Better than either of the these two though, and actually quite good, was “Angus, Thongs and Perfect Snogging”, a film which made Eastbourne look like the sort of place it would be nice to live. The one real negative point of “A, T and P S” though, was that it gave a glimpse of what it might be like to live in a house with teenage daughters, something which will begin to happen in less than one month’s time. Save me.