Friday, 20 November 2015

Team about to leave Belgium for Antarctica

This Saturday, Quentin Laffineur  (RMI) and Christian Hermans (Institute for Space Aeronomy) will start their journey from Belgium to Princess Elisabeth station Antarctica. As mentioned before, they will take care of all measurements and instrumentation for the AEROCLOUDproject. The scientific activities will take place in the framework of this year’s scientifc  Belgian Antarctic expedition  (BELARE 2015-2016), which is organised by the Polar Secretariat and the Belgian Federal Science Policy (BELSPO). The expedition is supported by the Belgian Secretary of State for the federal science policy, Ms Elke Sleurs, and is also supported by the Ministry of Defense (logistic support and personnel).
After arrival, Quentin and Christian will check several instruments for detecting clouds and precipitation, and properties of ambient aerosol particles. For the first time, all these instruments have been operational whole year-round. This means, also during the time when the station is uninhabited and the instruments rely on remote control. They will also re-install several instruments which cannot operate for several reasons during Antarctic winter (Cimel sunphotometer, Brewer ozone spectrophotometer), or which have been in Belgium for repair. In addition, there are again some newcomer-instruments.  In total, Quentin and Christian will have to deal with 13 instruments, plus the automatic weather station and weather balloon launches, and this within just tight 4 weeks. I wish them all the best and good luck for their work.

Tuesday, 10 November 2015

Instruments still operational and station is about to be opened again for the summer

The first Belare (Belgian Antarctic Research Expedition) team for this austral summer is about to arrive at Princess Elisabeth station. Their flight from Cape Town to Antarctica is scheduled for tomorrow. After arrival at the station they will be busy to prepare the station for austral summer operation. This means to clear the accumulated snow, check the IT- and power generation system, setting up again the water procurement system, and everything else what is needed for daily life at the station. Further teams will arrive one week and two weeks later. With that third team, also a first group of scientists will arrive. From our institute, it will be Quentin Laffineur who will join the Belare team. It will be his second stay in Antarctica. Last season he has been there together with me. This time, our colleage Christian Hermans from the Belgian Institute for Space Aeronomy will also join. It will be his first time in Antarctica. Quentin and Christian will take care of all instrumentation for atmospheric composition and cloud, precipitation detection, the automatic weather station, and they will also be responsible for regular launches of weather balloons. In addition, there will be some new instruments to be installed. Quite a lot of work. I will describe these instruments later in more detail and, as usual, we will also tell how life is about at Princess Elisabeth station.

monthly values of the particle number concentration (in cm3) from Nov-2014 ('1') to Oct-2015 ('12')

Another very important point is that our instruments are still in operation,without any break. We are very near to a complete year of data, two weeks missing yet. This is a great succes - having these kind of instruments in operation, only by remote control, without human direct maintenance, in these harsh environmental conditions and mainly sustained by renewable energies, is quite unique. This also means that we have already a very nice data set for our main scientific project AEROCLOUD at the station. The graphic above shows the monthly means of total particle concentration (in number per cm3) for November 2014 ('1') to October 2015 ('12'). The blue bars are the medians and blue and red together give the average value. Also the error bars are given. As already told in my last post, a nice seasonal cycle can be seen, also the influence of some events during which the number concentration increased distinctly (what causes that the median and average values differ markedly). The increase from August to October is very steep and the concentration for October is relatively high, especially when comparing with the concentrations during the summer months December to March. There have been several events during which the concentrations increased to some thousands of particles per cm3. There is a lot of promising information to be exploited scientifically. So, as the season is about to start, I will try to update this blog regularly.

Thursday, 3 September 2015

Record for duration of data time series

We are now in September, this means deep winter in Antarctica is over and more and more sunshine is coming back. There is already more than 10 hours sunlight per day at Utsteinen. And the instruments are still operational, without any break since the last team left Utsteinen in February !! This means a new record. The longest period for continuous aerosol data until now has been from November 2013 until the morning hours of 1 September 2014. This is great news and many thanks have to go to the team members who prepared the station’s energy system for the uninhabited period (and who are supervising it remotely from Belgium). But it also means that our own precautionary measures for unattended instrument operation are paying out. Now let’s hope that it keeps going until another BELARE expedition team arrives at Princess Elisabeth station.
Particle number per cm3 at Utsteinen from November 2014 to August 2015
The figure shows the time series of the particle number concentration from November 2014 until end of August 2015. The data are cleared of any contamination. It can be seen that from November to March the mean concentration was around some hundreds of particles per cm3, with a peak around end of February/beginning of March. The mean number concentration decreased afterwards to reach a minimum in June, July. In August, number concentrations started to increase again. During June and July, the number concentration fell to some tens of particles per cm3. During austral winter, the Antarctic vortex, the atmospheric circulation, forms a quasi-barrier for air masses from lower latitudes. Also during winter, there is hardly any sunlight for driving photooxidative aerosol chemistry and there is a general lack of precursor gases for new particle formation and condensational growth of particles. However, over the whole time period, there were several events, when the number concentration increased distinctly over very short periods of time, often to some thousand particles per cm3. Most probably, these periods reflect the influence of air masses transported to Princess Elisabeth station via synoptic scale events (cyclones, transporting air masses from easterly directions, including maritime origin), indicate entrainment of air masses from the higher troposphere, or indicate periods when new particle formation could be detected at PE.

Friday, 27 February 2015

All under remote control

Time has been flying and in the meantime it is end of February 2015. Princess Elisabeth station is uninhabited since two days. During the past two months, Johnny, the station’s main engineer, took care of our instruments and also of the balloon radio soundings. All instruments have been operating fine, including the sunphotometer. At the very last days of Quentin’s and my stay we managed to get the sunphotometer operational. It appeared to be an ordinary power issue – a loose contact at the battery. It is very good that this instrument has done measurements now for two months – for the vast Antarctic continent there are very few of its kind installed, although its main output, the aerosol optical depth (AOD) is a widely used parameter in global chemical transport models. Our other problem child, the size distribution instrument, had itself no failure. But, unluckily, during a storm in mid-January very little snow intruded into the aerosol measurement container, however, exactly onto the laptop which was used for that instrument. Snow smelts and thus the laptop broke… Nevertheless, help arrived with a feeder flight beginning of February. That flight brought in Stephan Bracke from RMI’s department in Dourbes. He came for installing new instrumentation for Geomagneticobservations. But he also brought with him a new laptop for running the aerosol size distribution instrument. So, we were lucky to have at least a total of 6 weeks of data from this instrument. At the end of the season, Johnny dismounted it and it will be repaired and calibrated in order to be re-installed during summer season 2015-2016. Like this instrument, also the Cloud Condensation Nuclei counter (CCNc) of TROPOS (Leipzig, Germany) and the sunphotometer will be shipped back. The sunphotometer will undergo its yearly calibration (in addition, there is hardly enough sun for it during winter) and the CCNc will be used for other measurement campaigns (and hopefully will be back next season). The Brewer ozone spectrophotometer also has been dismounted. It could continue with its measurements automatically, however, its mechanics and optics are very sensitive. If anything happens during the winter months – there is nobody to quickly stop it or repair it – and the risk is too high that this very expensive instrument encounters serious damage. It is stored safely in PE until next season. The ground equipment and antennas for the radio soundings are also shipped back to Brussels. We want to compare some of these radio sondes with the radio sondes type we are using operationally in Brussels. This will help to raise the confidence and accuracy of the radio sondes’ data. Altogether, this meant a lot of dismounting and packing work for Johnny. And a lot of cargo-customs-paper work for me. Now, there remain four aerosol instruments operational – the TEOM-FDSM, the aethalometer, the nephelometer and the condensation particle counter. At this place I want to express my gratefulness to Johnny who took great care of all the instrumentation! Now lets keep fingers crossed that everything goes well down there in the Antarctic.

Monday, 15 December 2014

Works are going on

We are not only busy with instruments directly at the station. We also went to the automatic weather station a few hundred meters to the East of the station in order to maintain it. Its data logger was partly damaged in mid-June during heavy winds (up to 26 m/s). We had a new one with us and replaced the old one with the new one. Parts of the measurements of that automatic weather station are temperature sensors in the ice for a vertical temperature profile. As there is every year some snow accumulation (some years more, some less, with a high variability), these sensors are not anymore at their original depth and therefore new ones are placed. If possible, the old ones can stay connected to the data logger. Another important piece of information for the interpretation of snow accumulation comes from snow profiles, i.e., the digging of a pit/hole of around 1.5m depth. One determines the different layers of snow (e.g., hardness, crystal size, form), measures temperature, ice crystal habits, and takes measures for deriving the water equivalent in mm of the different layers. Quentin and I went to dig such a snow pit on a calm sunny day and the views one has are really beautiful. The snow knife is necessary to cut out the cylinder for the water equivalent measures out of the surrounding ice.
We also continued the trials and repairs to get the laser instrument for measuring the size distribution of particles and the sunphotometer back to operation. Very likely, the sunphotometer has an issue with its motorized robot system and somehow the delicate system of gears and pins to detect zero and other pre-defined positions has been de-routed. It is still not working and we get a bit desperate on it. On the other side, we managed finally to get the laser instrument back to work. It took quite a few emails with the manufacturer and trials/repairs on the internal cabling of the electronic steering boards. It appeared that its internal pc was broken. We had to connect an external pc via a serial cable to the electronics of the instruments, got the software from the company, and after some typical trial and error work on the serial connection, the instrument measures since Sunday noon again. This is very good news. The data of this instrument are also very important for interpretation of the cloud condensation nuclei counter. So, in the evening we granted ourselves one or two glasses of fine whiskey.
In addition to this and the routine work on the other 10 instruments we launched every day a radiosonde with a balloon. If there is not much wind, it is no problem to hold the Helium-filled balloon until the radiosonde is ready (i.e. until the receiving signal of the GPS is stable). But during stronger winds, the balloon is bouncing in every direction behind our place of a container and it looks like a fight man against balloon :-)
Now we are already in our last week at Princess Elisabeth station. The schedule foresees that we leave the station on Friday or Saturday, probably Friday. This means to prepare all instruments in a way that the engineers and technicians remaining at the station can easily handle or check them.

Sunday, 7 December 2014

There is something in the air

Today on 7 December we have launched our 10th balloon with the new system and we got as usual good data on the vertical distribution of temperature, humidity, wind and pressure up to 32 km altitude (however, it needs to be said that humidity is only reliable up to around 10 km). All launches have been good until now and we are happy that we are able to create a database of the meteorological and dynamic conditions in the higher atmosphere around Princess Elisabeth station. To launch such a weather balloon it is necessary to be with two. One prepares the radiosonde which measures and transmits the data and the other holds the with Helium filled balloon until launch. At some days the wind has been very strong and it was not always easy to hold the balloon until the sonde is ready and is fixed to the balloon. During strong winds at launch time, the balloon bounces back and forth and tries to escape …
All the instruments we have set up are used to follow the evolution of aerosol (particle) properties around Princess Elisabeth station. Most of the time the conditions are relatively constant and not much special is happening. But, yesterday – we went to check routinely our instruments – we saw that the particle concentration was increasing. From the normal baseline of 200-300 particles/cm3 during summer it went suddenly up to 6000 / cm3. It happened during strong winds from eastern directions and contamination by the station can surely be ruled out. It is more probable that this was linked to the approaching of a major cloud system. The lower cloud level was decreasing when the particle concentration went up. When the concentration reached maximum and thereafter, the cloud level was increasing and the clouds even move away. The instrument from Leipzig told us that the concentration of particles being able to form clouds has not much increased during this event. So, there are some questions for us to be answered, how clouds, the whole lot of particles and particles, which can form clouds, are linked. That’s why we are here. This morning the concentration of particles was again at the usual level around 300 / cm3. And no strong winds anymore.

And, yes, also in the far region of Antarctica, St Nicolas does not forget the well-behaved.