Saturday, 18 November 2017

Cape Town

I arrived in Cape Town on Tuesday 22:30 local time (GMT+2). With me there are Nadine from ULB and Christophe from UGent for our CHASE project; Frank and Jean-Louis of ULB, Stef of TU Delft, TJ of Taiwan and Emmanuel and Etienne from Canada, all six for the Mass2Ant project; Henri our bird expert (Natural Sciences Institute/museum); Jacques the station’s doctor and Daniel (field guide) from Switzerland; and finally Baptiste, Olivier (BE) and Jacques (CAN) completing the station’s staff. 

Unfortunately, our flight to Antarctica is delayed. Mainly due to bad weather in Antarctica, also the planned flights before us encountered delay and this delay has to be recovered to bring in all the waiting teams of the different research stations. The unfavourable weather will persist at least until Tuesday. So, we will fly only by Wednesday to Antarctica. Hopefully. Almost one week of delay will put pressure on our and the station’s staff time schedule at Princess Elisabeth station. 

view southwards from Cape of Good Hope
Meantime, we are preparing what could nevertheless be done from here – collecting the polar clothing from IPF and checking that we do not forget any small item for the equipment and project. But of course we are also enjoying Cape Town, its pleasant weather and the surroundings. Yesterday, on Friday, we hired a car and drove to the Cape of Good Hope (the most south-westerly point of Africa). On the way there, we stopped at Boulders Beach were a colony of around 2000 African Penguins (Sphenicus demersus) lives. It is the only species breeding in Africa and it is listed as an endangered species. 

 Scientists at Cape of Good Hope
 African Penguins

Sunday, 22 October 2017

New research season ahead

This winter – or better summer in the Southern Hemisphere – our research at Princess Elisabeth station will restart. Besides the AEROCLOUD project, for which I will leave to Antarctica, there are three more scientific projects, in which colleagues of the Royal Meteorological Institute (RMI) are involved: CHASE, GEOMAG and MASS2ANT. The expedition is organized by the Belgian Polar Secretariat and its operator, the International Polar Foundation.

As described before, within the AEROCLOUD project (financed by the Belgian Science Policy Office programme BrainBe), the RMI collaborates with the Catholic University of Leuven and the Belgian Space Aeronomy Institute in order to investigate relationships between aerosol, clouds, precipitation and climate in Antarctica. Aerosol particles are necessary for the formation of clouds, which transport the necessary humidity to Antarctica for precipitation, which in turn is the only way how the Antarctic ice sheet is gaining mass. Our range of up to 15 scientific instruments is quite unique in Antarctica and the gained data will serve to improve regional climate models in order to better understand how the Antarctic ice sheet will behave in a changing future climate. This season, I will leave Belgium mid-November and I will stay until 20 December at Princess Elisabeth station.

The almost five weeks will be filled with the maintenance and calibration of the aerosol, cloud and precipitation instruments. The instruments could in general operate whole-year round, but they have been without power since my last post. Therefore, I will be busy with a lot of checks if the instruments are working properly and I hope that not too many repairs will be necessary and that there will be no serious damages. In addition, I will re-install the Brewer ozone spectrophotometer and the Cimel Sun photometer on the roof of the station. The Brewer is important to monitor the evolution of the total atmospheric ozone column (this year’s ozone hole appears to be a relatively ‘smaller’ one; link) and the incident UV-A and UV-B radiation. The Cimel measures the extinction of the solar radiation by particles. Further, I will restart together with colleagues and the station staff the weather balloon launches in order to derive vertical profiles of temperature, humidity and wind by radio soundings.

AEROCLOUD is not the only project I will be working on. There is also the CHASE project (financed by the Belgian Science Policy Office programme BrainBe), in which my institute and I are collaborating with the University of Ghent (UGent), the Université Libre de Bruxelles (ULB) and with the Vrije Universiteit Brussel (VUB). Two colleagues, one of UGent and one of ULB will stay during the same period as I at Princess Elisabeth station. Within CHASE we face the challenge to study the chemical composition of atmospheric particles, collected on filters and within surface snow. We want to analyse both the organic and inorganic composition as well as conducting isotopic analyses on the samples. Because the overall aerosol amount in the Antarctic atmosphere is very low, we will apply pumps which generate a very high air flow rate (more than 300 L/min) which will be maintained over several days for one single filter sample. This is in order to gather enough mass on the filters to guarantee a sufficient signal-to-noise ratio in the analyses. With the results we will get more insight on the relative importance of, e.g., trace elements, (persistent) pollutants or micro-nutrients like iron. The chemical signature of the collected aerosol will help us also to identify the potential source regions (e.g., Southern Ocean, South Africa or South America) and the relative importance of natural against anthropogenic sources.

Further, there is another scientific project of RMI going on at Princess Elisabeth: GEOMAG. Within this project (financed by the Magnetic Valley initiative of the Belgian state), the RMI is installing a 100-% automatic ‘magnetic’ observatory in Antarctica, complementing an international network of respective observatories (INTERMAGNET). It will be the first complete observatory in an uninhabited environment. The infrastructure and two instruments have already been installed in February 2015. In February 2018, two colleagues of RMI (from our department in Dourbes) will install the ‘GyroDIF’, which measures automatically the absolute magnetic field, the reference value for the more routine measurements of the variations of the magnetic field.

Finally, there is the project MASS2ANT (financed by the Belgian Science Policy Office programme BrainBe), in which the Universit√© Catholique de Louvain, the Universit√© Libre de Bruxelles and RMI are working together. MASS2ANT aims to investigate the local processes responsible for the variation of the surface mass balance in the Princess Ragnhild coastal region and also to document the changes during the last 300 years by drilling ice cores. Furthermore, the project wants to establish links between local processes and processes at larger scale with the help of combining and linking models of different scales (both in temporal and spatial resolution). This will enable to get a better understanding of the surface mass balance variation at larger scale. 

Friday, 1 July 2016

In freezing mode

Finally, we have not been lucky this austral winter. On 21 May, there was a huge storm, with hourly averages of wind speed up to 27 m/s and 6-min-peaks up to 38 m/s. In the course of this storm, the communication link to the stationwas interrupted and could not be restored (if the storm has been the cause can’t be confirmed, however). Also other satellite communication means did not work anymore, indicating that the station had also lost power. The reasons are not clear (as there is no communication link to explore…). So, this means that everything is now in ‘freezing’ mode. Inside the station and in the scientific shelters, there should be no issue for the instruments – it should be dry and relatively ‘warm’. However, the power outage means also that there is quite a lot of maintenance work to be done when the next BELARE campaign starts in November this year. In particular, the instruments which are installed on the roof of PE station have to be checked in detail. Last year, when everything operated without interruption during winter, it was much less maintenance work. We also hope that the instruments have not encountered damage during that huge storm, and also that the long time they will be now outside without being powered will not lead to damage. Only by mid-November, when the first team arrives at PE, we will know more details. Until then, we hope the best.

In the meantime, there is some time to go ahead with some data analysis. Below, a graph for the monthly means of the total particle number concentration is given, for all years/months available up to now. There are several striking points : a) there is a clear yearly cycle, with relatively high numbers  during summer and lower particle numbers during winter, b) winter numbers (May, June, July) are extremely low (down to some tens of particles per cm3), c) as soon as sunlight returns in spring (Sep, Oct), numbers go up distinctly, d) monthly numbers are well repeated each year, however with some annual variation, e) especially from November throughout March, the statistical means come with very high standard deviations. Some  explanations : during the summer months, transport of air masses from lower latitudes or the coast to PE station is more often than during winter when the strong atmospheric circular circulation around Antarctica (polar vortex) is forming a quasi- barrier for this kind of transport. In addition, there is also (almost) no sunlight which could trigger particle formation processes by atmospheric photochemistry. In September, October, sunlight returns, and also the polar vortex is becoming less stable, setting the scene for atmospheric particle formation and transport. The high standard deviations were caused by short-termed events (some hours to one day), during which the particle number increased from 200/300 per cm3 up to 6000 per cm3. Such events can be linked to either entrainment from the free troposphere and/or the passage of clouds with or without precipitation.

Wednesday, 6 April 2016

Successful season behind and promising winter season ahead

In the meantime we are already in April. High time to post something on the blog. The BELARE 2015-2016 expedition at Utsteinen has been finished end of February when the last team left Princess Elisabeth station. The expedition season has been successful for our project. All instruments for year-round operation have been maintained and are still operational.This means that now an un-interrupted time series exists from November 2014 to present for four aerosol instruments (aethalometer, nephelometer, TEOM-FDMS, U-CPC). The laser aerosol spectrometer has been re-installed after its repair and has been operational since December 2015 – and is still running. The Brewer ozone spectrophotometer could measure the whole austral summer season until mid-February when it had to be dismounted as usual. Below there is a graph showing the time series of total atmospheric column ozone from end of November to end of December 2015. It illustrates nicely the period until mid-December when ozone hole conditons (i.e. total ozone below 220 DU) persisted over the region of Utsteinen. Normally, such conditions persist only until end of November, beginning of December. The ozone hole of 2015 was indeed one of the most stable one on record. 
time series of total ozone end of Nov-2015 to end of Dec-2015

the MAX-DOAS (left) and the sunphotometer (right) instruments on the roof of PE station

The next image shows the sunphotometer (to the right) and the new-comer instrument ‘MAX-DOAS’ (to the left). The MAX-DOAS (Multi-AXis Differential Optical Absorption Spectroscopy) system is part of the BIRA contribution to the AEROCLOUD project. This instrument will monitor the vertical distribution of aerosols as well as several trace gases present in the atmosphere above the station. Like the Brewer, the MAX-DOAS measures the spectrum of solar light attenuated and scattered by atmospheric particles and molecules, in the wavelenght region of 300 to 550 nm, where a number of atmospheric molecules such as ozone and other compounds (NO2, BrO, OClO, H2O, O4) can be detected. By scanning the sky from the horizon to the zenith, the instrument provides information on the vertical profile of these molecules, as well as on aerosols which affect the measured trace gas absorption. First measurements are very promising and comparisons with the Brewer instrument (total ozone) and the sunphotometer (aerosol optical depth) show good agreement. In particular interesting is , that the instrument will continue its monitoring throughout the year. Therefore (if it keeps on running), it will be possible to observe the onset of the ozone hole as soon as the light starts to illuminate the polar stratosphere in early austral spring.. In addition, the concentration of several ozone related species (NO2, BrO and OClO) will be simultaneously measured providing an ensemble of data to characterize the chemical evolution of the polar stratosphere during the spring period. 

 the new instrument 'Snowflake Video Imager' on the roof of PE station

Our partners from the KU Leuven installed in January 2016 also a new instrument on the roof of the station, the ‘SnowflakeVideo Imager’ (see third image), designed by NASA. It contains a high-speed camera with sufficient frame rate, pixels, and shutter speed to record thousands of snowflake images in an undisturbed flow. These images are used to derive information on precipitating and blowing snow particle size distribution, as well as information about particle shape. This information on snow particles is important for correct estimation of snowfall amounts based on the radar measurements. A nice test for the instruments has been an impressive storm on 29 and 30 March 2016, with wind speeds around 20 m/s, peaking up to 26 m/s and after which the automatic weather station detected a snow accumulation around 20 cm. When writing this post, just another storm is active in the area of Utsteinen. So far, the instruments cope well with these conditions and the aerosol instruments are well in their cosy shelter (fourth image) – outside storm and very low temperatures, inside around 20 °C. 

inside the aerosol instrument shelter during winter season

Thursday, 3 December 2015

Aerocloud Teamhas arrived at Princess Elisabeth station

Quentin and Christian arrived safely last week Friday, early in the morning at 1am, at Utsteinen. Unfortunately, our air cargo boxes carrying several scientific instruments  (like the new MAX-DOAS, the radiosounding equipment or the Laser Aerosol Spectrometer) have not been with them for their flight to Antarctica. The boxes were still in Amsterdam for for us unknown reasons, although they were picked up in time in Belgium. Finally, they arrived end of November in Cape Town, South Africa, and will be flown in by the next Ilyushin cargo flight, scheduled for today. After their arrival, Quentin and Christian checked that the already installed scientific instrumentation worked well, and  that all necessary accessories were there. 

 Measured effective UV Index at Princess Elisabeth station on 30 November 2015
As the weather conditions have been very good the last days, they have already been able to re-install the Brewer ozone spectrophotometer, which measures the total atmospheric column amount of ozone. This year’s ozone hole over Antarctica is one of the largest and total ozone amounts over Dronning Maud Land, the region where also Princess Elisabeth station is located, are still extremely low, between 150 and 200 Dobson units. As ozone protects us against the harmful UV radiation, lower total ozone values mean higher values of the UV index, which reached values up to 12 (!) during the last days. A value above 10 means that unprotected human skin will get sunburned within 10 minutes. At the station, the team members can follow the local UV index evolution in real-time and can thus protect their skin and eyes accordingly. The link to the near-real time UV index at Utsteinen can be found here (if there is no image, then the satellite link to the station is down at that moment). 

 The special cloud bringing very light snowfall and white frost to Utsteinen
But we are not only interested in atmospheric gases, also particles and particularly clouds interest us. A very special one occurred on Saturday, 28 November. In the evening, a close-to-the-ground stratus, resembling to fog, was advected from NE. During the time of its passage, visibility was significantly reduced, light snowfall was present and there was white frost formation. Such white frost formation we have never before experienced at the station, very special thus. The event lasted bit more than 3 hours, and afterwards the white frost sublimated rapidly. The next days, Quentin and Christian will do some necessary calibration and maintenance work of the scientific instrumentation and will welcome the boxes with the other instruments and equipment.