Marcel Van Triest, official meteorologist of the Barcelona World Race, explains the extraordinary technology behind the decision to include Gough Island as a waypoint and move the first Atlantic ice gate.
 
Whilst the competitors were sweating in the heat of the Equator, the atmosphere was definitely chillier at the race office this week as the first results of a large Ice Study commissioned by the FNOB came in.
 
Until recently the various round the world races were held in ‘ignorant bliss’. No one knew anything about the Southern Oceans until they got there: there was little conventional shipping going through the area to speak off and satellites of the time only made visible or infra-red “pictures”. Due to the dominant cloud in this part of the world the visible images were usually useless and the infra-red failed to distinguish frozen icebergs in freezing conditions.
 
As a result the competitors were blind to any potential dangers. Thankfully (almost) no one got hurt during the early races and in retrospect we have been lucky.
 
These days, however, some satellites carry powerful on-board radar. When this radar is switched on a powerful radar beam is directed to the earth’s surface. As this beam reflects from the surface the resulting “scatter” is captured by the antennas of the same satellite. These satellites are polar orbiting (meaning that they circle the earth many times a day via the poles) and therefore the captured scatter gets stored on-board the satellite and downloaded to the ground the next time the satellite flies over an earth station.

The enormous amount of binary data is then reconstructed into an image (see below for an example of a 5km iceberg) and analysed by a team of experts at C-Core in Canada. As you can see the image is fairly coarse. That is because the resolution with which this study has been done is for targets of at least 150 metres. The reason for this is that the area to research is huge (the whole Southern Ocean) and the radar on the satellite is limited by power consumption and on-board data storage capacity. Furthermore image acquisition has to be planned days, if not weeks, in advance. All the images are special requests as, apart from round the world sailors, few people care what happens down there. Nevertheless the study done for the Barcelona World Race was the largest single order for this kind of images received at the European Space Agency (ESA)

 

Fortunately the end product dealt with by Race Management is slightly simplified.

The arrows show Gough Island and the large concentration of targets that obliged race management to add Gough Island as a waypoint of the race.

The first analysis of the scatterdata by C-Core was already of a major concern, as Mike Lynch of C-Core commented: “We’ve never seen anything like it.”

 

The reflection of the target was extremely large and there were a great number of additional targets around it, all of which was in a very Northerly position.

 

To make absolutely sure a search was done for imagery in the visible spectrum of the various satellites around the same date. We were lucky to find the below image of the High Resolution Modis satellite, without the ever-present cloud cover, confirming what the Envisat radar had already indicated.

 
 

The conclusion was that we were looking at a very large iceberg that had just “broken-up” resulting in multiple icebergs of more than 4 kms, dozens of icebergs of ‘a few’ hundred metres, and hundreds if not thousands of smaller pieces that cannot be reliably identified with this technology.

The resulting ice field would have been almost certainly presented a great danger for the fleet of the Barcelona World Race.

Technology has come a long way and there is still a long road ahead, but the round the world skippers need no longer be sailing ‘blind’.