Quadrennial Ozone Symposium: Preparing Final ... - PMOD/WRC

Bi-Polar UV activities at Finnish Meteorological Institute
K. Lakkala, O. Meinander, A. Karpechko, J. Kaurola, R. Kivi and E. Kyrö
Finnish Meteorological Institute, Finland
C. Torres, A. Redondas, R. Garcia and E. Cuevas
Institute Nacional de Meteorología, Santa Cruz de Tenerife, Spain
H. Ochoa
Dirección Nacional del Antártico, Instituto Antártico Argentino, Buenos Aires, Argentina
G. Deferrari
Centro Austral de Investigaciones Cientificas, Ushuaia, Argentina
Abstract. The Finnish Meteorologival Institute (FMI)
takes part in monitoring of UV radiation in both
hemispheres at locations, where polar ozone loss has been
detected. In this work UV data from Sodankylä (67 N) and
Jokioinen (61 N) have been used to represent the Arctic,
and UV data from Marambio (64 S) and Ushuaia (54 S)
represent the Antarctic. Maximum UV index values of the
studied period are around 5 and 6 in Sodankylä and
Jokioinen, respectively, whereas maximum UV index
values can exceed 7 and 9 in Marambio and Ushuaia,
respectively.
Arctic data
In the Arctic, in Finland, the FMI has UV measurements
using broad band SL501A radiometers, multiband NILU-
UV radiometers and Brewer spectrophotometers. In this
study Brewer measurements from Jokioinen and
Sodankylä are used. In Sodankylä, the measurement time
series start in 1990 (Figure 1.) and the Brewer MK II
spectrophotometer has a single grating monochromator
with a spectral range of 290-325 nm (Lakkala et al. 2003).
At Jokioinen, the Brewer MK III has a double
monochromator with a spectral range of 286.5-365 nm.
Both spectroradiometers are well characterized, regularly
calibrated against 1000W lamps and have participated to
international comparisons (Koskela et al., 1994; Kjeldstad
et al., 1997). The instrument at Jokioinen fulfills the WMO
level S-2 requirements (Seckmeyer et al. 2001) for
detection of trends in UV irradiance.
Antarctic data
In the Antarctic, in 1999, as part of the MAR
(Measurements of Antarctic Radiance for monitoring the
ozone layer, project REN2000-0245-C02-01 financed by
Ministerio de Ciencia y Tecnologia) project, a
multichannel NILU-UV measurement network was
established in order to measure real-time ground-based UV
and ozone values. The project was established by INM,
Instituto Nacional de Meteorología, Spain, in collaboration
with FMI, DNA-IAA, the Dirección Nacional del
Antártico-Instituto Antártico Argentino, and CADIC, the
Centro Austral de Investigaciones Cientificas, Argentina.
Within the MAR project, three NILU-UV radiometer
have been set up at Antarctic stations in order to monitor
ground-based ozone, UV and photosynthetic active (PAR)
radiation (Torres et al. 2002a and 2002b). The location of
the stations with respect to the stratospheric polar vortex is
interesting, as the vortex plays an important role in the
mechanism of ozone depletion. Belgrano II (77 S) is
mostly located inside the vortex; Marambio (64 S) is at
various time inside, on the edge of, or outside the vortex,
while Ushuaia (54 S) is mostly outside the vortex. Ushuaia
is one of the few inhabited towns situated in an area of
severe Antarctic ozone loss (Pazmiño et al. 2005).
Figure 1. UV index time series measured with the Brewer
spectrophotometer at Sodankylä 1990-2006.
Results
The ozone depletion mechanisms and extension in Arctic
are different from the Antarctic, and therefore the impact
on surface UV radiation is expected to have different
characteristics. To compare the differences, it is important
to use same irradiance scale for different measuring sites.
FMI has provided a traveling reference, NILU-UV
radiometer, which travels yearly between the Arctic and
Antarctic (Meinander et al. 2004). Using the radiometer
the wanted irradiance scale can be transferred to the
studied time series of Marambio (64 S), Ushuaia (54 S),
Sodankylä (67 N) and Jokioinen (61 N) (Meinander et al.
2004). The transfer of the irradiance scale is based on solar
comparisons made between instruments (Lakkala et al.
2005). Proper quality control, including regular lamp tests,

is also required.
The main feature, regarding the studied time series, was,
that higher maximum daily dose rates were measured in
our Antarctic sites than in our Arctic sites. This can be
linked to the more severe polar ozone loss of the Antarctic.
Maximum UV index values of the studied period where
found to be around 5 and 6 in Sodankylä and Jokioinen,
respectively, whereas maximum UV index values could
exceed 7 and 9 in Marambio and Ushuaia, respectively.
Sixth European Symposium on Stratospheric Ozone:
Göteborg. Poster presentation, 2002b.
Acknowledgments The Academy of Finalnd has given
financial support for this work through project FARPOCC. The
MAR Project is financed by the National R+D Plan of the
Spanish Ministry of Science and Technology (National Research
Program in the Antarctic) under contract REN2000-0245-C02-01.
The SUV spectroradiometer UV data from Ushuaia was provided
by the NSF UV Monitoring Network, operated by Biospherical
Instruments Inc. under a contract from the United States National
Science Foundation's office of Polar Programs via Raytheon
Polar Services Company. We are grateful to Bjorn Johnsen of the
Norwegian radiation Protection Authority for relative response
measurements. We thank the operators of the MAR project.
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