By Alessa J. Geiger & Max Zundel
As autumn commences in the southern hemisphere it seems the low-pressure cells are keen to share their full monty with us. This has led to the total cessation of decks and laboratory work with waves of up to 8 meters and winds of up to 10 Beaufort (see weekly report 6). Faint hints of high pressure have been experienced since returning to the Chilean continental margin, hence the most has to be made out of the short period they last. Hence having a direct line to our “Weather Max” is of advantage. Officially Polarstern hosts two employees of the German weather service on board, with Max Miller as our Meteorologist and Hartmut Sonnabend as technician. Routinely the weather briefing is scheduled for 8:15 am every morning, unless an earlier fieldwork start is anticipated to exploit a good weather window, in which case it usually takes place at 7 am.
Max usually provides an overview of the current weather situation at the position of Polarstern and toward the desired destinations for the day. He includes information on type of system (i.e. high or low pressure), expected wind strengths and direction, the associated sea state (i.e. average wave heights) information on possible showers and minimum cloud elevations. Typically we look at the 24h projections, emphasis on projection, in detail but we also need to keep an eye out on the 2-3 day forecasts for deck and land work. Following his weather assessment and forecast, direct discussion between the chief scientist Frank Lamy, the captain Stefan Schwarze and Max Miller takes place. Based on the forecast it is discussed whether Polarstern can go to the
desired locations and what work can or cannot be performed at said location. Sometimes this means that initial work plans have to be adjusted, canceled or swapped. After that, interaction between Max and the Helicopter team takes place . Here weather conditions are specifically discussed from a flying perspective.
The helicopter operations on board follow visual flight rules. This means if fog, showers, clouds or anything else obscure sight, flights cannot take place. Similarly the strength of the wind is not allowed to exceed a certain speed. If the wind speed is too high, the flights are cancelled or postponed for safety reasons. Lastly the sea state influences whether the helicopter can be made flight-ready on the landing deck and also if it can land safely.
Lars Vaupel and Harold de Jager are the land geologists direct point of contact for helicopter flights. Depending on how many land groups need to get ashore, all people involved discuss the best way to meet all needs, with the chief scientist and captain making the final calls. In some cases this means, that one group gets flown out to one site, taking a survival kit with them, whilst the helicopter returns to Polarstern to fly out the second group, etc.
Our fieldwork depends on good communication lines between all parties involved. So far the land geology groups have managed to set up three geodetic stations, have sampled for thermochronology and/or cosmogenic nuclide dating on three sub-Antarctic islands, the Antarctic peninsula and on Isla Londonderry, southern Chile and have managed to take lake cores from Cape Horn Island and Noir Island, southern Chile (including over-night stays). Though we all had many more sites we wanted to sample, the present exploit is surprisingly good given the mostly difficult weather we had to deal with. This attests to everyone contributing towards marking it work. Special thank goes out to the logistical people behind making our science work possible!
best wishes, Alessa J. Geiger & Max Zundel