Monitoring of atmospheric compounds at high latitudes is a key factor for a better understanding of the processes driving
the chemical cycles of ozone and related chemical species. In this frame, the GASCOD (Gas Analizer Spectrometer
Correlating Optical Differences) equipment is installed at the Mario Zucchelli Station (MZS - 74.69S, 164.12E) since
December 1995, carrying out observations of nitrogen dioxide (NO<sub>2</sub>) and ozone (O<sub>3</sub>). The recent advances in sensor technologies and processor capabilities, suggested the setup of a new equipment, based on the same optical layout of the 'old' GASCOD , with enhanced performances and improved capabilities for the measurements of solar radiation in the
UV-visible spectral range (300-700nm). The efforts accomplished, allowed for the increase of the investigated tracers.
Actually, mainly due to the enlargement of the covered spectral range and to the adoption of a CCD sensor, in addition to
the NO<sub>2</sub> and O<sub>3</sub> compounds, others species can be monitored with the new instrumental setup such as bromine, chlorine and iodine oxides (BrO, OClO and IO). The innovative equipment called GASCODNG (GASCOD New Generation)
was installed at MZS during the 2012/2013 Italian Antarctic expedition, in the framework of the research projects
SAMOA (Automatic Station Monitoring Antarctic Ozonosphere) and MATAGRO (Monitoring Atmospheric Tracers in
Antarctica with Ground Based Observations) funded by the Italian and Portuguese Antarctic programs respectively. In
this paper a brief description of the new equipment is provided, highlighting the main improvements with regard to the
'old' one. Furthermore the full dataset (1996 - 2012) of NO<sub>2</sub> total columns, obtained with the GASCOD installed at MZS,
is compared with the data obtained with satellite borne equipments (GOME, SCIAMACHY, OMI and GOME2) and the
main statistical parameters are analyzed and discussed in detail.
The use of CFCs, which are the main responsible for the ozone depletion in the upper atmosphere and the formation of
the so-called “ozone hole” over Antarctic Region, was phase out by Montreal Protocol (1989). CFCs' concentration is
recently reported to decrease in the free atmosphere, but severe episodes of ozone depletion in both Arctic and Antarctic
regions are still occurring. Nevertheless the complete recovery of the Ozone layer is expected by about 2050.
Recent simulation of perturbations in stratospheric chemistry highlight that circulation, temperature and composition are
strictly correlated and they influence the global climate changes. Chemical composition plays an important role in the
thermodynamic of the atmosphere, as every gaseous species can absorb and emit in different wavelengths, so their
different concentration is responsible for the heating or cooling of the atmosphere.
Therefore long-term observations are required to monitor the evolution of the stratospheric ozone layer. Measurements
from satellite remote sensing instruments, which provide wide coverage, are supplementary to selective ground-based
observations which are usually better calibrated, more stable in time and cover a wider time span. The combination of
the data derived from different space-borne instruments calibrated with ground-based sensors is needed to produce
homogeneous and consistent long-term data records. These last are required for robust investigations and especially for
Here, we perform a review of the major remote-sensing techniques and of the principal datasets available to study the
evolution of ozone layer in the past decades and predict future behavio