- honora on SnowSAR continues with successful flights in Canada
- Christian Mätzler on SnowSAR continues with successful flights in Canada
- Carl on Tales from a cherry picker
- Best of the Web 31/03/2012 - Ice Warrior on 100 years on … the spirit of international collaboration and our polar regions
- honora on A broken power inverter brings delays
Author Archives: honora
From Chris Derksen (Environment Canada) 22 April 2013
Following completion of the SnowSAR flights and ground measurements near Inuvik, the entire operation transferred to Alaska.
This included a rather complicated effort to ship the SnowSAR and aircraft installation (modified aft baggage doors for the Cessna-208 Grand Caravan) fromInuvik,Northwest Territoriesacross the border toFairbanks, Alaska.
Although these two communities are only separated by about 500 km by air, they are not efficiently connected either by air or ground. TheAlaskaand Environment Canada field crews made the nearly 3000 km road trip, starting with a southbound drive on the infamous Dempster highway to DawsonCity.
The Dempster, with its rough gravel surface, is known for eating tires, and the Environment Canada truck did not emerge unscathed.[caption id="attachment_1613" align="aligncenter" width="640"] Wrecked tire (Environment Canada)[/caption]
Nevertheless, three days after leaving Inuvik we crossed the Atigun Pass, through to the north slope ofAlaska, and arrived at theToolikLakefield station, operated by theUniversityofAlaska–Fairbanks.
Unfortunately, the shipping of the radar and aircraft doors toFairbanksdid not go smoothly. Owing to a series of missed steps beyond our control, the projected timeline for conducting the SnowSAR flights continued to slip.
Fortunately, our luck turned and thanks to some quick processing of our shipment by United States Customs. The SnowSAR instrumentation arrived safely inFairbanks, where the MetaSensing operator was waiting for the installation onboard a Cessna 208. The customised cargo doors for the SnowSAR antennas (X-band on the top window, and Ku-band on the bottom) can be readily interchanged among different C208 aircraft platforms, so we were ready for science flights on 18 and 19 April.[caption id="attachment_1614" align="aligncenter" width="640"] Customised doors (Environment Canada)[/caption]
The acquisition site was 600 km north ofFairbanks, and was reached with a 1.5 hour ferry flight. Before beginning the radar acquisitions, a short stop and go was performed at a small landing strip (nearGalbraithLake, at the north end of theBrooks Range) for coordination with the ground team.
The SnowSAR acquisitions began overToolikLake, where 12 corner reflectors were placed for radiometric calibration.[caption id="attachment_1616" align="aligncenter" width="427"] Caravan approach (Environment Canada)[/caption]
The tracks left by the snowmobiles reveal the locations of the targets in three parallel lines, one for the co-pol corners, one for the cross-pol at X band, and one for the cross-pol at Ku-band. The field station facilities can be seen in the bottom right of the aerial image.[caption id="attachment_1617" align="aligncenter" width="640"] Snow survey lines (Environment Canada)[/caption]
Our American colleagues had already started the snow measurements in the Imnaviat Creek watershed, which included an intensive 1 km by 1 km grid of snow survey lines.[caption id="attachment_1618" align="aligncenter" width="640"] ‘Crop circle’ patterns (Environment Canada)[/caption]
One unique aspect of these ground measurements was a FMCW radar (designed, built, and operated by Dr. H-P Marshall,BoiseStateUniversity) operating in the same frequencies as the SnowSAR. This instrument was also deployed during SnowSAR flights inAustriain February. In the photos below, you can see 1 km snow survey lines (separated by 100 m) and ‘crop circle’ patterns where the FMCW acquired measurements in a spiral pattern.
The snow cover properties at Imnaviat Creek inAlaskawere markedly different from Trail Valley Creek nearInuvik. Meteorological conditions combined to create a depth hoar layer at Imnaviat that was remarkable. These large faceted grains are found at the bottom of the snowpack, and form as a result of temperature-induced vapor pressure gradients in snow. In over 30 years of snow surveys at Imnaviat, our colleague Matthew Sturm noted that he had never seen depth hoar crystals as large as what we measured this year. The grid spacing in the photo below is 2 mm, so this depth hoar crystal was approximately 14 x 12 mm in size. The impact of these large crystals on the airborne SnowSAR measurements will be important to determine.[caption id="attachment_1619" align="aligncenter" width="640"] Depth hoar crystal (Environment Canada)[/caption]
Despite some stressful moments when our timeline was slipping, in the end we managed to acquire nearly coincident airborne SnowSAR and LiDAR measurements, with detailed ground-based surveys, in harsh Arctic environments, in two countries, separated by only 8 days. More than 15 hours of SnowSAR acquisition flights were achieved inAlaskaandCanadain the last two weeks, from which more than 250 SAR strip images will be obtained.
Over the coming months we will quality control all the ground measurements, and the final SnowSAR and LiDAR datasets will be processed. These various datasets will then be utilized to improve our knowledge of X- and Ku-band radar response to snow cover properties, and our ability to retrieve snow water equivalent (the amount of water stored in solid form by the snowpack) from these measurements.
Ultimately, we will combine our work with the analysis of SnowSAR data acquired inFinlandandAustria, to maintain the current momentum behind radar remote sensing of snow. Now that the melt season is imminent, the SnowSAR will take well deserved vacation…unti the next mission of course!
The success of this ambitious data acquisition plan (as well as the campaign periods in December and March) was due to the hard work of many people and organisations. A big thanks to:
- MetaSensing for the installation and operation of the SnowSAR, particularly Alex Coccia for his flexible travel schedule;
- Pilots and staff at North-Wright (Inuvik) and Wright’s Air Services (Fairbanks);
- Lake Central Aircraft Services for the development of a flexible aircraft installation for the SnowSAR;
- Staff at the Aurora Research Institute and Toolik Lake Field Station for their logistical support;
- The large group of participants who contributed to ground data collection, often under harsh Arctic conditions;
- EnvironmentCanada, the European Space Agency, and NASA Terrestrial Hydrology Program for financial and logistical support
From Chris Derksen (Environment Canada)12 April 2013
The final phase of the Canadian SnowSAR campaign is now complete, with successful flights conducted over the Trail Valley Creek study site on 8–9 April.
There was a major addition to the experiment – an airborne LiDAR system was also flown, onboard a turbo Otter aircraft on 6–7 April.
The same flight lines were covered by both the SnowSAR and the LiDAR. So, we will have 1 m resolution snow-depth estimates from the LiDAR to compare with the SnowSAR measurements and the blowing snow model simulations that will be conducted at Environment Canada.[caption id="attachment_1603" align="aligncenter" width="640"] Otter aircraft on approach. (Environment Canada)[/caption]
The LiDAR flights, funded by NASA, were coordinated by collaborators at theUniversityof Alaska Fairbanks. Four scientists made the long drive fromFairbankstoInuvikto participate in the snow sampling during the campaign period.[caption id="attachment_1604" align="aligncenter" width="640"] Ground sampling. (Environment Canada)[/caption]
Conditions were cold and windy during most of the ground sampling period. The focus was similar to the previous measurements made in December and March: long snow-depth transects along the flight lines, and snow stratigraphy measurements to understand the layered properties of the snowpack.[caption id="attachment_1605" align="aligncenter" width="640"] Snow trench. (Environment Canada)[/caption]
Ground penetrating radar measurements were also performed. It was quite the achievement to keep all the cables untangled![caption id="attachment_1606" align="aligncenter" width="640"] Ground-penetrating radar and cables. (Environment Canada)[/caption]
The Inuvik campaign is now complete and we are in the midst of transferring the SnowSAR toFairbanks,Alaska, after which flights will be conducted near theToolikLakeresearch station.
While the radar is on its way via air, the ground team is presently waiting out a blizzard in Inuvik before making the drive toAlaska. A final blog post will be provided fromAlaskain a few days.
The final photo for this post shows the tundra landscape of the western portion of the Trail Valley Creek watershed. TheMackenzie River, surrounded by forest, can be seen in the distance. If you look closely, you can see a wide path of trampled snow, left by a reindeer herd that recently moved through.[caption id="attachment_1607" align="aligncenter" width="640"] Tundra landscape of Trail Valley Creek. (Environment Canada)[/caption]
From Chris Derksen (Environment Canada), 26 March 2013
The field team has gone home for a short break before another round of SnowSAR flights in April. They will return to the same cabin in which they stayed in March, located on the shore of Husky Lake. In the meantime, here’s a short description of the work we did on the ground to support the SnowSAR flights.[caption id="attachment_1592" align="aligncenter" width="640"] Cabin and snowmobiles (Environment Canada)[/caption]
In addition to the main cabin, there is a small structure with room for two or three people to sleep. During the busiest time of the campaign, three people also slept in a tent behind the cabin.[caption id="attachment_1593" align="aligncenter" width="640"] Northern lights (Environment Canada)[/caption]
We are currently in a period of unusually intense solar activity, so during some nights the team was treated to northern lights. Another northern phenomena is a ‘Sun dog’ – the scientific name is ‘parhelia’. This is the appearance of two small rainbows on each side of the Sun. They are created by the refraction of light from the low angle of the Sun through clouds that have a high ice content.[caption id="attachment_1594" align="aligncenter" width="640"] ‘Sun dog’ (Environment Canada)[/caption]
It’s been a heavy snow season on the tundra, so the field team had lots of snow to work with. There is evidence that high winds and blowing snow events have been less frequent than normal over the tundra this year.
The snow is less dense than expected, the snow drifts are smaller than normal, and the small patches of trees are covered in snow and rime. Rime is formed by the deposition of water vapour in cold conditions, and gives vegetated landscapes a sepia-toned appearance.[caption id="attachment_1595" align="aligncenter" width="640"] Tundra (Environment Canada)[/caption]
The field team made approximately 15 000 snow-depth measurements for comparison with the airborne radar data. These depth measurements can be acquired very efficiently using automated snow-depth probes equipped with a GPS.[caption id="attachment_1596" align="aligncenter" width="864"] Snow-covered trees (Environment Canada)[/caption]
To help interpret the radar signal, it is also important to understand the vertical structure of the snowpack.
How many layers are there? How dense is each layer? What is the grain size of each layer? The traditional way to acquire these measurements is to excavate a snowpit, and make a vertical series of measurements in the pit face. This captures the snow stratigraphy at a point.[caption id="attachment_1597" align="aligncenter" width="864"] Taking measurements in a snowpit (Environment Canada)[/caption]
It’s also important to understand how the layers in the snowpack vary over the land surface because snow properties can be very heterogeneous due to interactions with vegetation and terrain (such as slopes).
To better understand this variability, some of the field team excavated a 50 m long trench across one of the radar flight lines (see earlier blog post for a photo of the trench from the aircraft).
They then used a near infrared (NIR) camera to take sequential photographs along the length of the trench. The NIR reflectance is sensitive to the snow grain size along the face of the trench, so these photos will be analyzed to provide precise information on how the snow layers vary both vertically and horizontally.[caption id="attachment_1598" align="aligncenter" width="864"] In the trench (Environment Canada)[/caption]
The field team returns to Inuvik next week. In addition to the SnowSAR, we also anticipate measurements from an airborne LiDAR system. We will post further updates from the field.
Chung-Chi Lin (ESA) & Dirk Schuettemeyer (ESA), 18 March 2013
At the end of February, teams from the Finnish Meteorological Institute (FMI), GAMMA Remote Sensing and the Swiss Avalanche Service (SLF) successfully carried out the SnowScat vertical profiling experiment in Sodankylä, Finland.
The experiment was conducted to gain deeper knowledge about the stratigraphy of snow. It is part of the activities of ESA’s CoReH2O (Cold Region Hydrology High-Resolution Observatory) candidate Earth Explorer 7 satellite.
The instrument worked perfectly during the experiment. The scientists were also happy since the data that were collected as they looked very representative.
Developed by GAMMA in Switzerland, the ‘SnowScat’ instrument is a fully polarimetric scatterometer, coherent stepped-frequency continuous wave radar that operates in the range of 9–18 GHz.
SnowScat has been used in the last four winters in Sodankylä and produced a wealth of data for analysing snow mass, snow structure and snow-pack morphology such as stratification, grain size and type.
Until this part of the campaign the instrument worked with a similar viewing geometry as a potential satellite. However, it was the time to change this to have a closer look at the layering of snow. This involved some basic construction to move the instrument around, as you can see below.[caption id="attachment_1573" align="aligncenter" width="480"] Preparing SnowScat as it snows. (ESA)[/caption]
The campaign had good start since the weather and snow conditions at the time were rather favourable. The temperature rose to above freezing in the days preceding the experiment, causing partial surface melt. During the experiment, temperatures remained around freezing, so the hope was that some nice layering could be observed.
On the first day of the actual experiment, it snowed from the early morning until just after the mid-afternoon. It took the team the whole morning to set up SnowScat in these challenging conditions. Initially, the team couldn’t mount a functioning laser pointer on SnowScat, which obtains a rough pointing knowledge of the instrument.
Nevertheless, the team used their creative skills to attached a string with a weight (actually it was a wrench) to determine the true vertical direction. The antennas of the instrument were then visually aligned with an accuracy of better than say half a degree.[caption id="attachment_1576" align="aligncenter" width="480"] SnowScat with wrench. (ESA)[/caption]
Owing to the heavy snowfall, there was a rapid accumulation of snow on the instrument. The meltwater dripped from SnowScat and created small indents in the surface of the snow on the ground. We don’t know yet what effect this will have on the SnowScat signatures.
On the second day, the sky was mostly clear, and it didn’t snow.
For the actual data acquisition, the extension beam was swung manually around a pivot point at back of the instrument. SnowScat was then operated at 11 different positions along an arc of approximately 2 m.
The geometry is determined by the marks on the front-side railing as seen below. This string with the weight, i.e. the wrench turned out to be very useful, as it could be extended so that the weight was lowered at the end of the experiment to mark the nadir points on the snow surface for the snow-pit characterisation.[caption id="attachment_1579" align="aligncenter" width="640"] Snowpit team in action. (ESA)[/caption]
At each horizontal position, SnowScat was operated at five elevation angles, from –2° to +2°. At each elevation angle, it swept the maximum frequency range (9.5–17.5 GHz). It was determined that the responses were not so sensitive with respect to the precise pointing around the vertical.
At ±2°, the first peak became noticeably reduced, whereas the ground return remained comparable, which confirmed the assumption on the dominance of specular reflections from the snow surface and internal layers.
The team had to climb up the tower every time the extension beam was swung horizontally, but this helped to keep them warm! The first set of measurements from all the horizontal positions was completed by the end of the first day.
The same measurements were repeated in the morning of the second day. So, we now have two complete sets of measurements with two slightly different snowpack conditions, one during snowfall on a partially melted/slightly refrozen surface and the other on fresh snow layered on refrozen snow.[caption id="attachment_1586" align="aligncenter" width="480"] SnowScat on tower with Sebastian (SLF) on left, Andreas (Gamma) in the middle, and Lin (ESA) on the right.[/caption]
This is already an unique dataset in itself. To be able to really analyse the radar data and also be able to validate the data, the SLF team carried out some extensive in situ data sampling in the field of view of the instrument after the radar data acquisitions.
The different teams have returned home and started to analyse the data and can hopefully report on these measurements in detail soon.
From Chris Derksen (Environment Canada), 14 March 2013
After a strong blowing snow event on 12 March, clear and calm conditions provided a great window for SnowSAR science flights out of Inuvik, Northwest Territories on 13 and 14 March. Both were ideal days for flying: –25°C, clear skies, and very calm. A photo from the Cessna-208 shows the stark beauty of this Arctic landscape.[caption id="attachment_1564" align="aligncenter" width="640"] Arctic landscape from Cessna-208 during the SnowSAR campaign in Canada. (Environment Canada)[/caption]
The calm conditions were also welcomed by the ground team making final adjustments to the 12 corner reflectors used to calibrate the airborne radar measurements.[caption id="attachment_1565" align="aligncenter" width="640"] One of the 12 corner reflectors. (Environment Canada)[/caption]
In addition to the flight activities, there are currently seven personnel based out of a small cabin approximately 70 km from the town of Inuvik. This may not sound far, but when pulling full loads this trip takes about four hours by snowmobile.
The cabin is about 10 km from the study site, so the scientists commute daily from there. The ground survey team are continuing to conduct snow-depth transects, make snowpit measurements, conduct a ground-based LiDAR survey, and deploy a sled-based ground penetrating radar.
In this photo taken from the aircraft, you can see two scientists excavating a 50 m snow trench to determine the spatial variability in individual layers within the snowpack.[caption id="attachment_1566" align="aligncenter" width="627"] As seen from the aircraft, two scientists excavating a 50 m snow trench. (Environment Canada)[/caption]
This is an international project, with participants from Canada, the United States, England, and Finland. They are reporting excellent progress on the ground, with the only issue that one of the areas sampled intensively during ground measurements in December was subsequently trampled by a herd of caribou!
The ground team will continue their measurements until Monday, before packing up and returning to town. There will be only a short pause, before a second set of flights in early April.
These flights are the culmination of many months of planning. The ground measurements will be used to interpret the radar signal over snow covered tundra. Snow water equivalent estimates produced from the airborne radar will be compared both to ground measurements, and a distributed hydrological model run over the study area by Environment Canada.
This is a busy time in the campaign – we will post more photos from the field camp in a few days!
From Alex Coccia (MetaSensing), 8 March 2013
In the last week of February, the final European SnowSAR campaign for this winter in was accomplished. The campaign falls within the AlpSAR project supporting the preparations for ESA’s CoReH2O (Cold Region Hydrology High-Resolution Observatory) candidate Earth Explorer 7 satellite.
This latest campaign follows two other SnowSAR experiments that took place in November 2012 and January 2013, all in the same area ofAustria.[caption id="attachment_1541" align="aligncenter" width="640"] One of the three sites used for SnowSAR acquisitions. The Mittelbergferner, glacier in the Ötztal Alps. (MetaSensing)[/caption]
The breathtaking landscape of the European Alps around the Austrian–Italian border was the setting for operations.Innsbruckairport is the base of operations for the MetaSensing team operating the SnowSAR instrument.
It’s not an easy life for the pilots of the Cessna 208 Grand Caravan though, which hosted the measuring system, as Innsbruckairport is renowned for having a difficult approach because of the surrounding high mountains.[caption id="attachment_1542" align="aligncenter" width="640"] Cessna 208 at Innsbruck airport, the base of operations for the MetaSensing team. (MetaSensing)[/caption]
Flying the tracks for the SnowSAR acquisition isn’t a trivial task either, especially when clouds tend to hide the mountain tops.[caption id="attachment_1543" align="aligncenter" width="640"] Aerial view of the Austrian Alps. (MetaSensing)[/caption]
Despite the challenges, the SnowSAR campaign was successful with data being acquired over each of the three chosen sites, from 1000 m up to and above 3000 m above ground.[caption id="attachment_1544" align="aligncenter" width="640"] SnowSAR point of view on the alpine panorama. Dual frequency, dual polarisation X- and Ku- band radar. (MetaSensing)[/caption]
The image below was acquired at Ku-band, VH pol, over the Leutasch site in November 2012. On the right, corner reflectors deployed for radiometric calibration purposes can be seen.[caption id="attachment_1554" align="aligncenter" width="640"] Example of SnowSAR image. (MetaSensing)[/caption]
Although the field campaign is over, there is no time to relax. The data recently acquired are now being checked and pre-processed. Preliminary SnowSAR images from the November and January campaigns are also being released.
And, the SnowSAR instrument is already on its way toCanadafor the next stage of the campaign. Stay tuned!
From Daniel Steinhage (AWI) and Steen Savstrup (DTU Space), Antarctica.[caption id="attachment_1531" align="aligncenter" width="640"] Packing up (D. Steinhage)[/caption]
On 22 January, the weather was on our side and we prepared for the last remaining flights, which we carried out in the afternoon.
It was a great feeling to have successfully finished all the flights within the time we had, with no major setbacks. We are very confident with the data we acquired and once we get back, we will start processing analysing the them.
Once our scientific work was completed, and after we’d had dinner, we had to pack the aircraft and start the first leg of our return flight towards South Pole.
Unfortunately, as we well know, the Antarctic weather is not always cooperative and after a few hours into the flight we received the news that we had to return to Concordia because of bad weather at the pole.
Following another warm welcome in Concordia and another night’s sleep, we then again repacked our plane and collected all the weather forecasts and once again begin our journey to the South Pole and then on to Kohnen Station. After flying for 12 long hours, we finally arrived at our destination.
The next day, we had an early breakfast and after refuelling we began the last leg of the transit flight back to NOVO.
Once there, we uninstalled all the scientific instruments from the aircraft and prepared them for shipping.
Today, is 25 January which officially marks the end of the DOMECair campaign, which we are very pleased to say has been a success.
We now have to wait three days for our flight to Cape Town and then home.
From Daniel Steinhage (AWI) and Steen Savstrup (DTU Space), Antarctica.
Daniel and Steen update us on their challenges of flying over Antarctica to get to the Concordia station and starting the DOMECair campaign. The aim of this novel campaign is to collect measurements that will validate ESA’s Earth observation SMOS water mission and GOCE gravity mission.
The overcast weather at Kohnen station finally cleared today so we were able to leave the Novo airbase, or Novo Runway as it’s commonly called, and head towards the South Pole. We had flown to Novo and met the AWI plane that we will use to take measurements for the campaign. The map below shows the distances involved!
The flight involved crossing the Wohlthat Mountains, a mountain range that stick out through the ice sheet in central Queen Maud Land. The photo below shows the Nunataks, which are small areas of rock emerging above ice sheets and glaciers, and the ice-free mountain summits. In 10 days, we pass over this region again.[caption id="attachment_1506" align="aligncenter" width="640"] Aerial view of the Nunataks. (D. Steinhage)[/caption]
After a short stop for fuel at Kohnen station we continued our transit flight and arrived at the Amundsen-Scott at the South Pole at lunchtime the following day. The station operates on New Zealand time, which is UTC+13.
Kohnen is a small summer station and at the time of our fuel stop it was occupied by 17 scientists and technicians from AWI. Amundsen-Scott at the South Pole, however, is a huge station, today housing 167 people. The station consists of a huge main building, garages under the surface and a large summer camp as well as several remote buildings dedicated to various fields of research such as atmospheric chemistry, astronomy and seismology.
Kohnen and Amundsen-Scott are both located on the East Antarctic plateau at heights of almost 3000 m above sea level. The temperature at Kohnen is slightly warmer, approximately –20°C, while at the Pole the temperature is –25°C.
At Concordia we expected even lower temperatures, so it is a major challenge to keep aircraft and scientific equipment warm enough to function properly.
We arrived at Amundsen-Scott just a few minutes before a C-130 cargo aircraft of the US National Science Foundation, so we could not refuel right away. This gave us enough time to grab some lunch and to settle into two temporary buildings used during the summer season. It had been a long trip and we had to struggle to stay awake until dinner. Straight after we’d eaten we went to bed – this was 19:00 local time, but being in UTC it was at 06:00.
Today we received two contradicting weather scenarios for Concordia. Since Concordia operates at UTC+8 we had to wait until lunchtime at to get a weather report directly from them. However, we couldn’t rule out the possibility of incoming low cloud at Concordia, so we decided to play it safe and postpone the flight to tomorrow.
Since we had to wait, we ran some tests on our equipment. We wanted to see how the systems were dealing with the cold – the outside temperature dropped to –29°C and inside the cabin we were down to –10°C.
We also did reference measurements with the portable gravity meter at the gravity reference point at the station. The point is in one of the tunnels, which connect the main station building with garages, power plant, and the sewage system. The absence of any wind and the solid foundation allows precise readings, only the bitter cold – about –45°C made the work difficult.[caption id="attachment_1508" align="aligncenter" width="640"] Gravity reference point at the Amundsen-Scott station. (D. Steinhage)[/caption]
We woke early at 05:00 o’clock to learn that the weather conditions were excellent. Forecasts from Amundsen-Scott and Concordia were similar so we packed and prepared the aircraft and instruments for an early start. By 09:00 we were airborne and on our last transit leg to Concordia.
Concordia is a station jointly operated by Italy and France. In winter, the station is occupied by about 15 scientists and technicians, but in the summer up to 65 people show up.
Before the station was established, the first of two deep ice cores of the European Project for Ice Coring in Antarctica (EPICA) were drilled at this site. This core holds ice oldest ice, dating back more than 840 000 years. The second EPICA ice core was drilled in Dronning Maud Land at the Kohnen station where we refuelled on our way from Novo Runway to Concordia.[caption id="attachment_1510" align="aligncenter" width="640"] Aerial view of Concordia station. (D. Steinhage)[/caption]
Because yearly accumulation on the polar plateau is extreme low, just a few centimetres of snow, the summer camp at Concordia is set up year round.[caption id="attachment_1511" align="aligncenter" width="640"] Sunny weather for our landing at Concordia. (D. Steinhage)[/caption]
After spending a night in a new time zone we woke up very early and were the first at breakfast. Nevertheless, it took a while to sort everything out so we could start to our first campaign flight.
We choose one of the two calibration flights to begin with, flying two sets of 10 circles. The second flight today is targeting two profiles of the planned 350 by 350 grid around Dome C. By mapping lines, which are not adjacent to each other we are aiming to cover the grid with a wide spacing first, then fill in the profiles.
Between the two flights we carried out the first calibration of EMIRAD-2 with liquid nitrogen, the nitrogen had been especially flown in for us from the Italian base Mario Zucchelli. Since it’s a dangerous substance, Concordia didn’t have enough for a complete calibration.[caption id="attachment_1512" align="aligncenter" width="640"] Liquid nitrogen calibration. (D. Steinhage)[/caption]
Today we finished two-thirds of our scheduled programme. Among the flights we carried out are the star patterns centred on the American tower where RADOMEX from the DOMEX-3 campaign is mounted and currently obtaining data, along with two more lines of the 350 by 350 large grid.
We are slowly getting used to the low temperatures and high altitude of Concordia. However, the cabin is preheated every morning with a hot air blower. The only difficulty with the simple blower is that its temperature range is only hot or very hot.
This is sometimes a problem for the EMIRAD system, since it should be at a stable internal temperature while it is calibrated before take-off and maintain that internal temperature during the flight. However, by opening the curtains in the back of the airplane letting in cold air, and having the pilots operating the cabin heat appropriately, a reasonably stable ambient temperature for EMIRAD has been achieved.[caption id="attachment_1513" align="aligncenter" width="640"] Heating the cabin. (D. Steinhage)[/caption]
Daily flight planning is based on the forecasts for the Dome C area that are received by email in the morning before breakfast. Later observations from Concordia station are also available from the radio office.
Owing to in-coming cloud around lunchtime, consistent with forecasts from both the US service in Charleston and the Italian meteorologist at Mario Zucchelli, and satellite pictures, we had to cancel today’s flight.
In the evening, we gave a presentation to the station personnel on our project. The lecture room was fully booked and many questions from the station personnel led to an interesting discussion.
From Daniel Steinhage (AWI) and Steen Savstrup (DTU Space), Antarctica, 13 January
Since we arrived in Antarctica we’ve been able to install the two instruments on the aircraft and do a calibration flight in preparation for the campaign. This was all done at the NOVO station where we met the AWI plane before our planned flight to the Concordia station.[caption id="attachment_1486" align="aligncenter" width="640"] Commercial plane on the left, which brought us to Antarctica and the AWI plane. (D. Steinhage)[/caption]
On 10 January we first removed various instruments from the plane that had been used for the previous geo-scientific mission. We kept the gravity meter, the basic data acquisition system and some auxiliary devices that were installed in the plane.
Immediately after lunch we started installing the EMIRAD-2 horn antennas and its rack, which will be used to validate the SMOS measurements.[caption id="attachment_1487" align="aligncenter" width="640"] Daniel and the equipment spread out on the ice. (S. Savstrup)[/caption]
We were lucky with the weather; it was nice and sunny with just a little wind so that we were able to spread out the transport boxes. This made packing the removed equipment and the installation of the new stuff very easy.[caption id="attachment_1488" align="aligncenter" width="640"] Installing the EMIRAD instrument in the plane. (D. Steinhage)[/caption]
We continued with this exercise the following day and managed to finish by the early evening. The alignment of the two horn antennas was measured and first tests were successfully carried out.[caption id="attachment_1489" align="aligncenter" width="640"] Steen checking the EMIRAD. (D. Steinhage)[/caption]
The ground test of EMIRAD in the morning of Saturday 12 January went well as did the short test and calibration flight which we finished in time for lunch. The calibration was carried out above the ocean just north of Novo runway.[caption id="attachment_1490" align="aligncenter" width="640"] Calibration flight over the ocean (D. Steinhage)[/caption]
In the afternoon we packed the POLAR 6 aircraft with our spare parts and all the remaining equipment into our container for storage. Also our own polar gear had to be checked and reduced, since the weight on the transit flight is limited.[caption id="attachment_1494" align="aligncenter" width="640"] Checking the instruments during the flight. (D. Steinhage)[/caption]
By then we were ready for the transit flight. Unfortunately the weather was overcast with light snow and drifting. This stopped us going on to the Kohnen German research station, which was to be our first stop on the way to the Concordia station.
The other stopover will be at Amundsen-Scott station, which is an US scientific station at the geographic South Pole and where we will refuel.
From Tȃnia (ESA-ESTEC), Noordwijk, the Netherlands
Over the next few weeks we will be carefully following two intrepid scientists as they carry out an extensive airborne campaign, called DOMECair, in the far reaches of Antarctica to support two ESA missions.
The reason why Steen Savstrup from the DTU National Space Institute and Daniel Steinhage from the Alfred Wegner Institute (AWI) have headed out to arguably the loneliest place on Earth is to collect measurements that will validate ESA’s SMOS and GOCE missions.[caption id="attachment_1472" align="aligncenter" width="616"] Concordia base is on East Antarctica’s polar plateau – about 3280 m above sea level and about 1000 km from the coast.[/caption]
Not only will the harsh environment of East Antarctica’s polar plateau where summer temperatures drop to –40°C be challenging, but also the long flights over the vast expanse of nothing but ice will undoubtedly be tough. The plan is to fly across an area of 350×350 km centred at the Dome-C Italian –French base at Concordia, which is highlighted in the map above.[caption id="attachment_1473" align="aligncenter" width="524"] Planned flights for the DOMECair campaign. (ESA)[/caption]
One of the photos that Daniel sent on his way out to Antarctica last week reminded me of just how far away and isolated Antarctica is, and made me smile at the same time. This photo of the boarding times at the airport in Cape Town lists Antarctica – the continent – as the destination, sitting rather oddly between the highly-populated cities of London–Heathrow and Amsterdam![caption id="attachment_1474" align="aligncenter" width="640"] Outward bound – Antarctica the continent! (D. Steinhage)[/caption]
Anyway, the guys have arrived safely and the plan is that they use two different instruments installed in the AWI’s Polar-6 airplane to take validation measurements. One instrument supports ESA’s Soil Moisture and Ocean Salinity (SMOS) mission. This is an instrument, called EMIRAD-2, is an L-band radiometer that is similar to that of SMOS, but from the aircraft gathers images at much higher resolution.
Measurements to support SMOS are already collected routinely from a tower at the station – previous entries on this blog describe its set up and purpose. However, since the instrument is fixed on a tower these measurements are taken of the same spot on the ice. Spatial variability of the L-band passive signal around DOME-C has not been measured to date so the impact of this variability on SMOS measurements cannot be properly assessed.
In addition, the spatial variability in L-band passive signals also impacts the cross-verification of SMOS measurements with parallel missions from other agencies such as the NASA AQUARIUS and SMAP missions over the same site. Quantifying and documenting the spatial variability is thus important to establish long-term cross-calibrated multi-mission L-band measurement timeseries.
The other instrument is the AWI Lacoste and Romberg air–sea gravimeter, which will take gravity gradient measurements over the ice to support ESA’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission. These airborne gravity measurements can be propagated to the GOCE flight altitude and used to independently verify the satellite measurements of the local gravity gradients as well as to improve global and regional solutions to the gravity field models generated by the mission.
For the DOME-C area, airborne gravity measurements are sparse or non-existent and thus represent a gap in the required reference high-quality gravity anomaly maps. Airborne gravity measurement such as those expected through DOMECAir will also contribute significantly to parallel initiatives by the science community such as AntGP to collect and generate a continent-wide high-resolution gravity reference map.
Importantly, this campaign will be the first time that measurements supporting two different missions will be collected at the same time.
The next blog entries will be from the team, but in the meantime we wish Daniel and Steen lots of luck as they start the campaign!