03 Jan - 02 Feb
3rd January 2004 - 2nd February 2005
It's already a month since our first diary entry this season; time has definitely flown by since then. January was a busy month, but it can be summed up quite easily: it was either action-packed doing aerial photography or GPS, or we were on standby, doing office-based planning and post-processing work. Since we require totally clear skies to do the aerial photography sorties we inevitably have a substantial amount of waiting to do here, since the Antarctic is not renowned for its perfect weather! Despite this, we have managed to complete many of our target areas. When the weather allows us to fly over these areas for a few hours we have to get out to do it immediately and get as much done as we can before the cloud comes across again. On the days we couldn't go out flying we were often able to get out to collect more GPS positions in the local area, often by boat out onto the small islands in Ryder Bay. It's not like a normal office job here - when you wake up you could end up doing any number of different things that day!
Above: MAGIC with Geoff the pilot. Click image to enlarge.
The month began fairly slowly as we had a week of cloudy weather in all of the areas we wanted to photograph. In the meantime, we began a detailed survey of Rothera Point. The accurate GPS positions will be used to compile a new detailed contour map of the base, using the technique called photogrammetry. We will create the new topographic map using a pair of overlapping aerial photographs taken this season. The photos are positioned on a coordinate system using the GPS positions, which are always obvious features on the ground so they can be easily seen in the photographs. We are then able to generate lots of new height positions to create a 3D model of the landscape from the images seen in stereo. This will be converted into a contour model for the new map. We use a highly accurate GPS so that error is kept to a minimum from the start of the project. For the Rothera survey, we set up the GPS base station on a known survey point and then carried out a 'Fast-Static' Differential GPS survey, which means you take a second GPS receiver with you and an accurate position can be recorded in only 10-15 minutes for each of the ground control positions. When the results are post-processed the baseline between the two receivers is used to calculate the position of the unknown point to centimetre-level accuracy.
Each morning we have a look at the most recent meteorological satellite pictures to see whether any of our aerial photography target areas are clear. Dan, the Rothera weather forecaster, tells us what chance we have to do any flying that day. Our first aerial photography mission since the New Year was on 8th January, when we were able to complete a task on the east coast of the Antarctic Peninsula, on Foyn Coast.
Some of the biologists at BAS are interested in visiting this area next year so we needed to take photographs so that they can plan their field season and work out the best area to land a plane, set up camp and collect samples. The area was only an hour away from Rothera in the Twin Otter so we had completed the tasks in only 4 hours. Each time we return from doing a survey we need to sort out the film and prepare for the next sortie. The film is very large (9 inches wide and 80m long!) and it must be inserted into the film magazine in the dark room. We usually use black and white film but occasionally we use colour film for low-level missions such as penguin census photography. It is too large to develop by hand so we bring back the exposed film for developing in the UK.
Another two areas that we were able to complete on 14th and 15th January were large sections of the coast both to the north and south of Rothera. During each MAGIC field season we do a number of tasks for the UK Hydrographic Office. They are interested in having aerial photographs of the bays and coastal areas that are difficult to reach by HMS Endurance. This is often in areas with spectacular scenery and this time was no exception. Flying above glaciers that cascade down steep valleys into the sea from the high plateau or searching for islands amongst the sea-ice is certainly a unique experience.
Above: Airphoto sortie for the Hydrographic Office. Click image to enlarge.
On the 21st January it was clear in another area, in eastern Palmer Land at around 72° South. Our task here was to do reconnaissance photography for a planned Geology trip there in a future field season. This season, the camera has been updated and is now linked to a GPS so that the position of each frame is recorded when it is exposed. It uses Post-Processed Kinematic Positioning, which means a base station is set up on the ground and the GPS in the aircraft logs data from the satellites at the same rate. An 'event' is recorded in the data file each time the camera shutter is released. For the areas close to Rothera it is possible to set the base station up on the survey cairn at Rothera. For areas further afield, such as eastern Palmer Land, we choose another suitable spot, in this case Fossil Bluff. When we arrived at the survey area we found that low cloud had moved in from across the Weddell Sea, preventing us from being able to complete the photography. We did what we could in the cloud-free areas but eventually headed back to Rothera. We will have to complete this on another day.
Above: GPS on cairn at Rothera. Click image to enlarge.
Further areas completed so far are Ryder Bay and the area close to Rothera. The photography taken here will be used to compile a new map of the travel area close to the base, which includes the ski area up on the glacier and the islands out in the bay.
In the days that we couldn't get out to do aerial photography we were often able to go to some of the islands in Ryder Bay to do a GPS survey. The new positions collected will be used in compiling the new map of the area. Most of these are pre-existing survey points so it involves searching for the small cairn or survey nail, using the survey station descriptions. We can record the positions to a much higher degree of accuracy using the dual-frequency GPS receiver, which we use in Fast-Static survey mode, with the base station set up on the Rothera survey cairn. While looking for points we had to keep a careful eye on the local wildlife, such as skuas and elephant seals!
Above: Looking for a survey point (top left); a GPS survey at Donnelly Island (top right); getting picked up by Stella (bottom left) and an elephant seal (bottom right). Click images to enlarge.
Further tasks on or around Rothera have included making measurements for positioning new field equipment for some of the scientists on base. A new antenna is being installed here as part of the global programme called DORIS, which, among other things will allow precise measurements on the earth's size and shape to be made. A further project is the installation of masts for meteorological measurements, as part of the SKiYMET Meteor Radar programme. Since the position of these is important we were able to help out using a theodolite and GPS to measure distances and angles to stake out precise locations for these instruments.
Also this month another MAGIC member, Paul Cooper, arrived to spend a month here at Rothera, on a separate project. Paul has developed a Geographical Information System (GIS) to manage field equipment that is left out in the field, initially in the area surrounding Rothera. It will enable an accurate record to be kept of the location and description of equipment (or other material) and the person responsible for its removal. This will also help BAS to meet requirements of the Antarctic Treaty, which states that the environment must be kept clean and nothing must be left behind here. Paul has been installing this system and training staff on base in using this software.
Towards the end of January the JCR made its call in to Rothera. The sea-ice to the south of Adelaide Island had cleared enough to enable a smooth passage, which was a relief after the first attempt in early December when she was forced to turn back. There were many happy people on base when she arrived carrying the cargo such as equipment, food and personal items and we had a busy couple of days helping to unload everything. It was great to see the crew again who have had a very busy time since we last saw them (see JCR web diary entries).
Above: JCR finally makes it to Rothera. Click image to enlarge.
So it has been an eventful month for MAGIC. We still have much left to do here: 3 areas of aerial photography must be completed and we have a number of GPS tasks remaining. We hope to finish these before we fly home on 8th March. You can read about how we get on in our next diary entry in early March.