Crossing the Antarctic Convergence Zone.
The great sailing conditions under good winds and nice weather experienced since we left behind the Beagle Channel and Cape Horn area, develop over the 450 nautical miles of open seas. That is the narrowest funnel of the Southern Ocean between Antarctica and the southernmost of the Americas. Here the Antarctic Circumpolar Current runs from the Pacific into the Atlantic. It is the most voluminous in the world, with an estimated flow rate between 950 to 1500 million cubic meters per second. The cyclonic systems formed in the Pacific Ocean traverse the passage in an easterly and southeasterly direction. A combination that makes the Drake Passage one of the most renown seas for its swells and tempestuous conditions. Characteristics that pay a good tribute to the temper of the man, sailor, explorer, privateer and pirate, already notable during his lifetime, considered a hero by the English during the Elizabethan Era, fighting the Queen’s enemy vessels over the known seas and seizing their riches. On the other hand, Sir Francis Drake was regarded as one of the most feared enemies by the Spanish. He dedicated his life balancing between the thin line between following the Queen’s orders during war state, but occasionally also targeting enemy ships when there was no war declared, falling into outlaw piracy. His adventures and journeys lead explorers who in the future would try their luck southwards until eventually reaching Antarctica. Trips where the first adventurers, whalers and sealers had to rely on the knowledge of their navigators to find their positions on the world using Dead Reckoning techniques and the sights and calculations of Celestial Navigation. Their readings and interpretations of the barometer, thermometers and the examination of the wind and cloud patterns were giving them an idea of how the oceanic conditions and winds would be in their near future. A task that nowadays sees itself being much easier by the use of the modern electronic equipment and communications installed aboard. Weather forecasting is crucial to plan itineraries, routes to follow and steering directions. This discipline was initiated by the same Captain Robert Fitz Roy who discovered and mapped the Beagle Channel. During his extensive naval career he developed great interest on the subject, knowing by own experience the value of advance warnings of storms at sea. Pioneer on that field, he designed and used the first weather-stations, creating a system of meteorological warnings including the first daily weather forecasts. From the 19th century, as the years passed, science progressed on some giant steps and his ideas germinate and grew on the computer simulations that we use nowadays, which give us pretty accurate information about the weather systems all over the world and their evolution, all ready available on-line.
These weather forecasts allow us to maximise the use of the winds for our progress to the planned destinations. And indeed good use of them our Captain and Mate do. So far, since the Europa left behind the coastal waters around the Beagle Channel, she has made a really good progress under sail. Strong Northerly winds made for a start of practically downwind sailing. Not the best for speed and steady steering. To try a faster progress and minimise a bit the rolling, during the late night and early morning hands are called on deck to gybe the sails a couple of times, to take the wind on a Broad reach and zig-zag our way southwards.
Later on, during the day, the winds from the North suddenly back to a more favourable Westerly and Northwesterly, the most typical winds to have across the Drake Passage. Yards and sails are adjusted to the 25 to 30 kn of those fair winds, a good situation that lasted for a few hours until it started veering again. All and all giving us the chance to keep the good sailing at speeds between 6 to 9kn. If we are able to keep them that will mean that tomorrow might be our last day in the Drake Passage. Approaching already the shores of the South Shetland Islands.
On that course this afternoon we all started to notice a cooling in the temperature, both of the air and the seawater.
The drop of several degrees on the oceanic surface tells us about entering the Antarctic system, leaving behind the more temperate Subantarctic waters.
Around the whole of the White Continent, this meeting area of both water masses is known as the Polar Front or Antarctic Convergence Area. Here the colder and denser waters from the South, sink under the lighter Sub Antarctic ones. This remarkable front was first measured in 1911 by the German scientific expedition led by Wilhelm Filchner on board the ship “Deutschland”. Those were the times where not much was known about Antartica, even though Scott and Amundsen were about to race to the South Pole itself. By then, Filchner organised a private enterprise to determine whether West and East Antarctic were connected by land or ice. They headed towards the virtually unknown coasts of the Weddell Sea on what ended up being an eventful and adventurous journey which lasted a couple of years, including an unplanned overwintering. They managed to sail further south than anyone else before, achieving important meteorological, geological and oceanographical observations. Brennecke, the ship’s Oceanographer, described the four isolated water masses in the Southern Ocean. Amongst his observations stand out his remarks of a sudden change in the salinity of surface waters flowing north, and an associated steep temperature plunge. He just had discovered the Antarctic Convergence, the oceanographic and biological boundary of the Antarctic Ecosystem.
The changes on temperature and weather also determine adjustments on the biodiversity, as we could also see on the differences on species and their abundance as trying to identify and count the seabirds that can be spotted from our decks. By doing that twice a day, Bark Europa collaborates with the collective called “Polar Citizen Science”, a community created to bring opportunities for research and public education by connecting researchers and research institutes with tour operators in the polar regions. Their aim is to meet the needs of the polar science community by engaging travellers in gathering data from remote locations. The seabird surveys are not the only project which we try to collaborate with, but also others like Whale photo identification, Seaweed and Kelp rafts in South Georgia and Secchi Disk to determine phytoplankton concentrations.