by Martin Revis
IS THERE any certain way of knowing what tomorrow's weather will be like? The United Kingdom's Meteorological Office claims its service
has a success rate of 86 per cent for next-day forecasts within the
United Kingdom and expects to do better in 1998.
The reason for optimism is the service's new Cray T3E supercomputer, capable of carrying out 80 billion calculations per second. Five
times faster that its existing Cray model with which it is running in
tandem before assuming sole command by the end of the year, the T3E
will process information from thousands of worldwide automatic and
human operated weather stations, satellites, aircraft and ships.
In the UK alone, 8,500 weather observations are produced each day
from 3,000 sites. Even so, the fickle climate will still sometimes
defeat the most advanced numerical forecasting techniques because the
atmosphere is too large and complex to depict with total accuracy
despite continuing advances in computer modelling.
Numerical forecasting drawing upon the principles of physics was
first devised in the 1920s but proved of little use until the advent
of computers because, by the time lengthy calculations were
completed, the weather had already happened. Similarly, before Morse
telegraphy developed in the 1840s no forecasts, however accurate,
could be transmitted quickly enough to be of any use except in the
immediate vicinity. Successful numerical models of the atmosphere
require a vast number of calculations to be made in the very short
time that only a computer can accomplish.
A spokesman at the Meteorological Office (or Met Office, for short)
at Bracknell, 30 miles (48 kilometres) west of London, explained that
where predictions failed - currently about one in seven for next-day
forecasts in the UK - it was most often because an error in timing
outwitted the human-machine mix making the calculations.
The Met Office, which employs some 2,200 people in 80 locations,
issues nearly 3,000 tailored forecasts and briefings daily for major
customers, such the Ministry of Defence Ministry and the Civil
Aviation Authority, as well as commercial enterprises such as the
offshore industry and shipping. Internationally, it participates in
the voluntary cooperation programme of the World Meteorological
Organisation for providing equipment and training to developing
The service's first large commercial licensing and development deal
for another national service is the present contract with Thailand to
set up a supercomputing capability to begin forecasting by November
Bracknell's new supercomputer will also help research into the El
Nino weather pattern, named after the Christ child because its impact
is strongest around Christmas. It occurs when the trade winds that
usually blow from South America to Australia subside, causing the
warm waters of the Pacific to drift eastwards provoking worldwide
weather chaos from drought to hurricanes, flooding and the
destruction of crops, most seriously in the developing countries of
Latin America, Africa, India and South-East Asia.
An alternative approach to forecasting has been developed by Weather
Action, a company founded by Piers Corbyn, an astro-physicist who
lectures in computing and mathematics at the South Bank University in
London. A staff of only 11 full-timers in this competitor to the
public sector Met Office, produce
forecasts on premium telephone and fax lines for the public and more
tailored predictions for insurance companies, power generators and
retailers in the UK. Swedish firms in the petro-chemical and energy
sectors have been among the first large overseas customers.
Mr Corbyn's system is described as enhancing the traditional methods
that involve forecasting the present atmosphere forward in time by
additionally identifying key changes in weather types that he sees as
being caused by solar activity. Information on solar activity is
collected from satellites and scientific sources, and forecasting -
particularly long term - is largely based upon the effect it is
believed to have on the distribution of high and low pressure areas
that control weather types worldwide. The precise method of
calculation is a trade secret, although it is intended to make it
Mr Corbyn claims that his company's long-term forecasts far surpass
in accuracy those of forward projection models by supercomputers,
which he views as having a reliable time horizon of only three or
four days. An independent study by the University of Sunderland,
north-east England, took one aspect - Weather Action's gale
forecasting data - and concluded that the possibility of the success
rate being due to chance was one in a thousand.
The Met Office maintains that it keeps an open mind but that at
present it does not feed solar activity into its calculations as it
has not found any correlation that would affect forecasts.
Competitive prediction claims are hard to evaluate because the basic
rules are so difficult to define. One national newspaper lets it
readers decide by printing Weather Action's forecasts alongside those
of the Met Office.
Mr Corbyn, who is sceptical of the Met Office's claim of
open-mindedness, makes no claim for infallibility. In his October
1997 long-range forecasting bulletin he explains that although
Hurricane Erika's crossing of the Atlantic in September 1997 was
correctly predicted by his service months ahead, the arrival of
tropical storm remnants in Britain in the form of heavy rain had been
lighter than expected.
Weather forecasting is likely to remain a British preoccupation.
Public tours of the Met Office are fully booked until early 1999 and
the topic remains as pervasive as when Dr Samuel Johnson wrote, more
than two centuries ago, that "when two Englishmen meet, their first
talk is of the weather".