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.
