IN The Merchant of Venice, the bad news comes at the beginning of the Third Act. "Antonio hath a ship of rich lading wrecked on the narrow seas, says Salarino. "The Goodwins I think they call the place a very dangerous flat and fatal, where the carcasses of many a tall ship lie buried."
The Goodwin Sands, off the southeast coast of England, claim fewer shipwrecks nowadays but that is not because the region has become less stormy. Or is it? One of the things that meteorologists like to do is to analyse data they have collected over the years to see if any trends become apparent. This has been done recently in the case of storminess on the North Sea.
There are three common ways in which the speed of the wind at sea can be assessed. It can be estimated visually, by observing the state and behaviour of the sea; one can use an anemometer mounted near the coast or on a ship; or one can calculate the wind at a particular spot by deducing it from the characteristics of the pressure pattern on a weather chart. When it comes to assessing long term trends in storminess, however, data based on all three methods have their drawbacks.
The first technique is subjective. Instrumental readings, on the other hand, are, in general, reliable but as the number of instruments has increased in recent decades, so too has the probability of serving a high wind in a specified area in any particular interval of time, and this may lead to spurious conclusions when comparing modern data with the sparse information of, say, a century ago. And in the era before satellite pictures small depressions over the sea might well go undetected, leading to underestimates in local winds inferred from weather charts.
A fourth technique suffers from none of these inconvenient disadvantages. Accurate pressure readings from a number of coastal stations around the North Sea have been available for a century or more and at any particular time the difference in atmospheric pressure between any two is a measure of the average wind strength in the region in between.
Readings from three such stations were used to obtain a measure of North Sea storminess from 1880 to the present day and the pattern found is interesting. It suggests that the 1880s was a very stormy decade, after which windiness dropped gradually to reach a minimum in the 1940s; since then the average wind has been increasing, with the early 1990s being comparable in storminess to the corresponding decade 100 years ago. These findings are consistent with the fact that here, in Ireland, the winter of 1993/94 was the stormiest in 10 years.