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 (NO2) and ozone (O3). 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 NO2 and O3 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 NO2 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.
Since the recognition during the seventies of the importance played by the minor atmospheric compounds in the climate
system (gases and aerosols), the studies regarding the chemistry and dynamical processes of Ozone (O3) and of nitrogen
dioxide (NO2) at high and mid-latitudes, became a fruitful field of research.
This work deals mainly with the retrieval and analysis of O3 and NO2 total columns and vertical profiles over the Evora
Observatory (South of Portugal) for the period 2007-2008. The products presented in this paper are obtained from
spectral measurements carried out with the UV-Vis. Spectrometer for Atmospheric Tracers Monitoring - SPATRAM,
installed at the Observatory of the Geophysics Centre of Evora (CGE) since 2004. The application of the Differential
Optical Absorption Spectroscopy (DOAS) algorithms to the spectral zenith-sky measurements is presented and
discussed. The inversion technique applied to the output of the DOAS procedures (the trace gases content along the
optical path of measurements: the slant column densities -SCD- of the analyzed absorber) are examined. The first
observations obtained with the SPATRAM instrument regarding stratospheric bromine oxide (BrO) are shown. In
addition, the comparison of the ground-based measurements with data derived from satellite equipments (OMI and
SCIAMACHY), are discussed.
The multi purpose UV-Vis. Spectrometer for Atmospheric Tracers Measurement (SPATRAM) is installed at the
Observatory of the Geophysics Centre of Evora (38.5º N, 7.9º W) - Portugal, since 2004, measuring the zenith scattered
radiation in the 300-550 nm spectral range. The main products are the total column and the vertical profiles of NO2 and
O3 obtained with the application of the Differential Optical Absorption Spectroscopy (DOAS) algorithms and with
inversion schemes based on the Optimal Estimation methods respectively. Recently (February 2009), the MIGE
(Multiple Input Geometry Equipment) was coupled to the SPATRAM instrument allowing for the measurements of the
diffused radiation in directions away from the zenith one (Off-Axis). MIGE is an alt-azimuth platform based on a very
simple optical layout, using an optical fibre to transmit the radiation inside the monochromator of the SPATRAM
equipment. Thanks to the solution adopted in the developing phase, MIGE is able to scan the whole hemisphere. In this
work, after a brief description of the MIGE, the first and preliminary results for vertical profiles of NO2 in the Planetary
Boundary Layer (PBL), and the values of Slant Column Densities (SCD) of O3 and SO2 measured in Off-Axis
configuration at Evora Station, are presented and discussed.
The recent increase in the ultraviolet radiation that reaches the ground, mainly due to the decrease in stratospheric ozone, demands high quality measurements over the world. For this goal the use of broadband instruments to measure erythemal-weighted irradiance is widely extended due to their low cost and easy maintenance and use. Nevertheless considerable efforts in quality assurance and quality control (QA/QC) are requiredin order to obtain a homogenised eryhtemal radiation from different regional and national networks over whole Europe. The laboratories that provide the calibration to these networks must guarantee reliable methodologies. For this purpose, the WG4 (Quality Control) within the COST-726 European action (Long-term changes and climatology of the UV radiation over Europe) is promoting the inter-laboratory intercomparison and the adoption of common procedures. In this work the procedures for calibrating broadband radiometers adopted by the laboratory "El Arenosillo" in Huelva, Spain, are presented. The methodology used at INTA has been intercompared with the UV laboratory at PMOD/WRC (World Radiaton Centre) in Davos (Switzerland) and results are presented in this document.
Long-term ground-based UV radiometers and satellite UV spectrometers have been utilized for detecting trends in UV
radiation and for establishing its climatology. The aim of this work is to compare noon erythemal (CIE) UV irradiance
data from NASA Total Ozone Mapping Spectrometer (TOMS) with ground-based measurements from a Brewer
spectrophotometer. The Brewer instrument is located at the Atmospheric Sounding Station "El Arenosillo" (ESAt) in
Huelva, Southwestern Spain. ESAt, with a high number of cloud-free days per year, is particularly suitable for
atmospheric-radiation studies and satellite validation. The period of study covers the years 2000 to 2004. The effect of
clouds and aerosols on the satellite vs ground-based bias is evaluated under different atmospheric conditions regarding
aerosol load and cloudiness. It is found that under all sky conditions TOMS overestimates the noon CIE irradiance about
8%. This bias is even higher (about 12%) for cloud-free days, showing statistically significant correlation with the
aerosol optical depth at 440 nm as measured by a co-located CIMEL-AERONET sunphotometer. However, for thick
clouds (high TOMS reflectivity) the bias becomes negative. Regarding aerosols, the bias increases as the aerosol load
increases, showing the highest values during dust events. All these facts suggest the need to correct the TOMS UV
products mainly under dust conditions.