Geoscience Reference
In-Depth Information
special interest for coastal applications. Remote sensing is a repetitive and stable
method to provide relatively cost-effective synoptic observations over the whole
large area of the Baltic Sea basin, including the Skagerrak and Kattegat. The strength
of remote sensing data is foremost to display the geographical patterns of complex
ecosystem processes. The use of remote sensing data in combination with in situ
measurements has greatly advanced our understanding of the Baltic Sea ecosystem.
The water of the Baltic Sea is optically very complex. Remote sensing com-
bined with a number of autonomous in situ monitoring techniques can be used to
analyze the spatial dynamics and seasonal patterns of the Baltic Sea. In situ data
are required to develop bio-optical retrieval algorithms, to validate them, and to
assure the quality of the derived atmospheric and in-water products. In situ data are
obtained from ships-of-opportunity, dedicated sea-truthing campaigns, and optical
moorings. Remote sensing and bio-optical monitoring are relatively new disciplines,
but have already significantly increased our understanding of the Baltic Sea ecosys-
tem. Further development of ocean colour technology and retrieval algorithms in
combination with advanced in situ instrumentation, and complex bio-geochemical
coastal zones models, may lead to a revolution in knowledge and management of
There is a strong need to further link up remote sensing and operational
in situ techniques with conventional monitoring techniques in order to secure
quality-controlled synoptic monitoring of the Baltic Sea. This is also crucial for
improved management of the Baltic Sea. The objective of the Helsinki Commission
(HELCOM) for the protection of the Baltic Sea environment is to maintain its bio-
logical status and diversity as expressed in the Baltic Sea Action Plan (HELCOM
in situ monitoring, Secchi depth and chlorophyll are used as biological indicators
for water quality. Reliable water quality maps can now be derived from MERIS
data and will be used in future to monitor and evaluate the HELCOM objective of
restoring water transparency. Furthermore, they can be used to monitor the effects
of eutrophication from space. The wide aerial coverage, the repetition and continu-
ity of the satellite observations, the consistency of the measured data, and a relative
cost-effectiveness clearly respond to the demands of a modern operational moni-
toring system. MERIS is now able to sense water quality parameters in the coastal
zone and will in future be increasingly used in integrated coastal zone management.
More research is needed in order to realize the full potential of remote sens-
ing in the Baltic Sea. This objective is addressed by the MERIS Date Quality
Working Group in collaboration with the MERIS validation team. One major goal is
to develop and validate atmospheric correction procedures over optically complex
waters, as well as to improve and validate adjacency corrections, so that subse-
quently the retrieval of water quality parameters can be improved. Furthermore,
ESA is going to continue its ocean colour mission. The Ocean and Land Colour
Instrument (OLCI), an instrument optically similar to MERIS, will be launched
on SENTINEL-3 in 2013, and is planned to be operational until 2023. This will
allow for continuous and consistent long-term trend assessment of water quality
and climate change induced effects in the Baltic Sea basin.
