The search for missing Malaysian Airways MH370 is becoming focused on a remote area of the southern Indian Ocean, famed for its turbulent weather patterns.
Satellite identification, and possible visual sightings of wreckage have concentrated search efforts in a region lying within the Roaring Forties. The Roaring Forties are so called because of the consistently strong winds which blow between 40 and 50 degrees latitude south. Average wind speeds are between 28 and 45 kph.
The difficulty in coordinating a search and, hopefully, rescue mission in an area which lies around 2,500km from Perth, Australia’s most westerly city, are obvious.
Unfortunately the weather likely to be encountered will do the reconnaissance mission no favours.
Preliminary searches by the Royal Australian Air Force were hampered by low clouds which extended from a height of 800 metres down to sea level. Further south, it is the strong winds and active weather fronts which sweep through the region which will hamper any visual sighting and tend to sweep any wreckage far from any initial identified location.
The strong winds in this region arise from the action of the Ferrell Cell which results from the interaction between the balmy weather of the sub-tropics to the north and the frigid polar vortex around Antarctica.
Between 40 and 50 deg S there is an absence of any landmass, save for the relatively narrow southern part of South America. This means there is little frictional force to slow the winds as they blow largely uninterrupted over the relatively smooth sea surface.
Historically, the region was welcomed by sailors during the Age of Sail. Then, the Forties could be counted on to speed the passage from Europe to Australasia via southern Africa. The same ships would then continue to make use of these winds before rounding Cape Horn, the most southerly point in South America before turning northwards back towards Europe.
The Roaring Forties also play their part in the development of ocean currents which can be expected to cause debris to drift in an easterly direction at approximately 0.7 kph. But this is complicated by disrupting eddies within the flow.
Inevitably, in a data-sparse, little used area of the globe, meteorological information is limited. Satellite data is the main source of information. Inevitably weather forecasts are less reliable than in more densely populated and used areas of the globe.
Nevertheless, it is expected that weather conditions will be reasonable in the next day or so before deteriorating as further weather fronts sweep through the region later in the week.