Professor Brian Golding of the Met. Office gave this year’s Christmas talk. This is traditionally a ‘family’ event and indeed attracted seven or so younger listeners and no doubt a good few more member’s spouses than usual.
Prof. Golding suggested that Noah and Aristotle were famous forecasters from history, Noah getting a special mention for actually acting on his forecast, (something not always practised nowadays?). Early forecasting was based on observing local patterns of weather and nature. He gave us a range of cryptic West Country sayings, (perhaps hoping for an interpretation of the more obscure?).
The introduction of the telegraph in 1840 brought a major change in forecasting as observations could be now received from all over the country. Vice-Admiral FitzRoy set up the original meteorological office in 1854 and began what became known as synoptic forecasting, the production of a synopsis or general description of the weather system on the scale of the UK. Prof. Golding thought that the forecast for the D-Day operations was probably the most momentous use of this method, where the observation of a weakness in an Atlantic front was matched with a depression in the North Sea and used to predict a relative lull in stormy conditions.
New technology in the form of the computer began to make practical the fulfilment of 19th century dreams of solving the Newtonian and gas equations, i.e. numerical forecasting. Early attempts in the 1950’s using ENIAC took two weeks to produce a daily forecast. In the UK the Met. Office were able to begin experiments using the first LEO computers, performing 100 decimal calculations per second. The latest computer is expected to be capable of 23 x 1015 decimal calculations per second. (The growth of computing power is remarkably constant, about an order of magnitude every 5 years).
The next new technology was the use of satellites, the first weather satellite being launched in 1962. Now cloud patterns over Europe can be mapped at five-minute intervals and supplemented by a whole host of measurements by other satellites throughout the day.
New measurement sources and increasing computing power has allowed the development of models using cells 25 km x 25 km on the base and with 70 levels up to 80 km in altitude. For the UK it is necessary to model on a 1.5 km grid in order to obtain the resolution needed to get sufficient accuracy for a 30 km x 30 km area, ‘city-level resolution’. During the Olympics the Weymouth area was modelled on a 330m grid to cope with local geographical features. The importance of having sufficient resolution was also demonstrated by showing how what was adequate for some areas could result in the Lake District being reduced to a single hill. These models are used to produce ‘ensemble’ forecasts, a set of forecasts using slightly different initial conditions and allowances for uncertainties. In this way it is possible to produce a measure of confidence in the certainty of each forecast. The trend was for numerical forecasting to get better over the years; the accuracy of longer term forecasts becoming comparable to those of shorter term forecasts of only a decade or so ago.
Prof. Golding went on to describe the various services that the Met. Office offered ranging from the ‘weather where you are’ on the public website through to informing government and public utilities about risks from severe wind, flooding and temperatures. Early and accurate warnings, for example, had been able to prevent damage to power infrastructure and ensure that the sick had been supplied with essential medication.
The Met. Office was no longer just concerned with weather prediction. The experience of Chernobyl had shown the need to map and predict the spread of airborne pollutants, smog and even disease carrying insects! Work was taking place to predict ‘space weather’, solar storms, which can disrupt communication and power systems. It was expected that ultimately the ‘ground’ models would need be extended upwards to link with the ‘space models’.
Prof. Golding took more than the usual number of questions from the audience with good grace, a fair few relating to past ‘failures’! Some of the more interesting questions produced an explanation of the various methods of measuring rainfall, (gauges, balances, droplets and radar) and a method for the public to contribute data via WOW.
Overall this was a very interesting talk though perhaps not directed as much to a younger audience as usual for these events, (but don’t underestimate an enthusiastic youngster!). From an engineering point of view it was a demonstration yet again how technology, (i.e. telegraph, computers, satellites and the internet), enhances other fields, something that we must keep reminding politicians, the media and our young.
Prof. Golding said that the over-40’s get their ‘weather’ from the TV; below that age it is via smartphone or Facebook. Notwithstanding the fact that other people are looking out on my behalf, from retailers to road gritters, it occurs to me that I’m not really bothered, if I hear or see a weather forecast it goes in one ear and out the other. Is that just me or is it a ‘British’ thing? Perhaps to some extent we are all ‘not bothered’, the UK climate being relatively benign. However it is no bad thing to be reminded of some of what goes on in the background to ensure that for most of us the weather remains just a topic of conversation and not a crisis.