1 Joint Research Centre of the European Commission, Ispra, Italy 2 Universität Hamburg, Hamburg, Germany
Contents
Barale and Gade
(Preface)
Part 1: Introduction
Barale
(The European Marginal and Enclosed Seas: an Overview,
6 pp.)
Allan
(Remote Sensing of the European Seas: a Historical Outlook,
6 pp.)
Part 2: VIS & TIR passive/active RS
Berthon et al.
(Ocean Colour Remote Sensing of the Optically Complex European Seas,
12 pp.)
Santoleri et al.
(Observing the Mediterranean Sea from Space: Ocean Colour Algorithms and Chlorophyll Variability,
12 pp.)
Kopolevich et al.
(Case studies of optical remote sensing in the Barents Sea, Black Sea, and Caspian Sea,
12 pp.)
Ruddick et al.
(Optical Remote Sensing Applications in the North Sea,
12 pp.)
Siegel and Gerth
(Optical Remote Sensing Applications in the Enclosed Baltic Sea,
12 pp.)
Lavender
(The Seasonal and Longer Term Variations in the Phytoplankton of the
North Eastern Atlantic Ocean: from the Irish Sea to the Bay of Biscay,
12 pp.)
Ambar and Dias
(Remote sensing of coastal upwelling in the northeastern Atlantic Ocean,
12 pp.)
Brockmann and Stelzer
(Application of Optical Remote Sensing in Intertidal Flats,
12 pp.)
Donlon
(The Next Generation of Multi-Sensor Merged Sea Surface Temperature Data
sets for Europe,
12 pp.)
Taupier-Letage and Millot
(The role of the thermal infrared images in the revision of the surface
circulation schema in the eastern basin of the Mediterranean,
12 pp.)
Dransfeld
(Current Tracking in the Mediterranean Sea using Thermal Satellite Imagery,
12 pp.)
Babichenko
(Laser Remote Sensing: Technology and Applications,
12 pp.)
Part 3: Microwave passive/active RS
Skou
(Microwave Passive Techniques: Radiometers and Radiometry in General,
12 pp.)
Font and Camps
(Microwave Aperture Synthesis Radiometry: Paving the Path for Sea Surface Salinity
Measurement from Space,
12 pp.)
Hoogeboom and Lidicky
(Introduction to Microwave Active Techniques and Backscatter properties,
12 pp.)
Stoffelen
(Scatterometer Applications in the European Seas,
12 pp.)
Alpers et al.
(Observing Internal Waves Generated in the Straits of Gibraltar and Messina from Space,
12 pp.)
Horstmann
(High Resolution Wind Field Retrieval from Synthetic Aperture Radar,
12 pp.)
Askne and Dierking
(Sea Ice Assessment by Means of Synthetic Aperture Radar,
12 pp.)
Romeiser and Runge
(Current measurements in coastal waters and rivers by along-track InSAR,
12 pp.)
Greidanus
(Ship Detection by Satellite Imaging,
12 pp.)
Solberg and Brekke
(Oil Spill Detection in European Waters: Approaches, Algorithms and
Guidelines for use,
12 pp.)
Ferraro et al.
(The Use of Satellite Imagery from Archives to Monitor Oil Spills in the Mediterranean Sea,
12 pp.)
da Silva
(SAR Observation of Rip Currents off the Portuguese Coast,
12 pp.)
Ziemer
(Wave and Current Observations by Ground Based X-Band RADAR,
12 pp.)
Gurgel and Schlick
(Fundamentals and Applications of Land-Based Radar Techniques for
Monitoring the Coastal Zone,
12 pp.)
Kern et al.
(Sea Ice Parameters from Microwave Radiometry,
12 pp.)
Tsimplis et al.
(Can we Reconstruct the 20th Century Sea Level Variability in the Mediterranean Sea on
the Basis of Recent Altimetric Measurements?,
12 pp.)
Cipollini et al.
(15 Years of Altimetry at Various Scales over the Mediterranean,
12 pp.)
Part 4: Synoptic / Multisensor
Gade and Barale
(Satellite Remote Sensing of Coastal Discharge Plumes: a European Test Site,
12 pp.)
Lavrova et al.
(Multi-Sensor Observation of Meso-Scale Features in European Coastal Waters,
12 pp.)
Sandven
(Sea Ice Monitoring Using a Multisensor Approach,
12 pp.)
Pozdnyakov et al.
(Combined visible and infrared remote sensing of the White Sea biogeochemistry and hydrology,
12 pp.)
Glossary Index
Abstracts
Allan, T.D.: Remote Sensing of the European Seas: a Historical Outlook
It is almost 30 years, since 3 pioneering spacecraft, operating in the optical, thermal and microwave spectral range,
demonstrated to a community of largely sceptical oceanographers that variations at the sea surface could be observed
to useful accuracies. Today there is a dozen ma-rine-oriented satellites in orbit, providing oceanographers several
kinds of data according to their need. Substantial progress has been made in under-standing satellite signals reflected
from the sea surface. Europe has estab-lished its position as a major player in Earth observation, having proceeded to
build, launch and support Envisat, one of the most sophisticated plat-forms in the world. Its scientists have made good
use of both European and non-European data and have made significant contributions to our knowledge of marine processes.
Although it is accepted that many envi-ronmental research programmes must continue as far as possible the time series of
satellite repeat observations, there are signs that ESA and the EC, in jointly supporting the GMES programme, are seeking
to look at a wider range of benefits. For a system to become operationally useful, the signal from the satellite should
be interpreted and presented to the ‘clients’ in the form most useful to them. Then, this information should be delivered
regularly, at a frequency matched to the development of the feature, so that the clients can take appropriate action.
In Europe, we have made significant progress in the first of these, but there is some catching up to do with the second.
Sensor accuracy and resolution have improved, but the 4 main sur-face parameters measured to useful accuracy in 1978 -
roughness, slope, temperature and colour - remain the same monitored today from Envisat and other spacecrafts. What is
not always fully appreciated is that the early caveats about satellites viewing only the sea surface – although essentially
justified – were offset by the wealth of detail revealed in the record of processes within the volume of the sea, which
produce a measurable sur-face signature. What we have learned is that satellites alone are rarely the whole answer to any
problem. The ability of satellites to fly year after year above the weather, maintaining a continuous record of those
observations at the sea surface, represents in itself a remarkable technical achievement and one in which Europe can
justifiably take pride. There remains the thorny issue of establishing services that could deliver information in near-real
time on a regular basis to interested clients. top
Alpers, W., P. Brandt, and A. Rubino: Observing Internal Waves Generated in the Straits of Gibraltar and Messina from Space
The Straits of Gibraltar and Messina are areas where strong internal solitary waves
are generated by the interaction of tidal currents with shallow underwater ridges
located in the straits. Remote sensing techniques have been very instrumental in
studying the generation and propagation of internal solitary waves in these sea areas.
For example, the first hint that internal waves are generated in the Strait of
Messina came from a Seasat SAR images acquired in 1978. Furthermore, ERS SAR images
have revealed that internal solitary waves generated in the Strait of Gibraltar
propagate only eastward into the Mediterranean Sea and not westward into the
Atlantic Ocean. Later in-situ measurements and model calculations have confirmed
these satellite observations. In this paper we present several satellite images
acquired in the optical and microwave bands showing sea surface manifestations of
solitary internal waves in these sea areas, in-situ measurements of solitary waves
and results from model calculations. In particular, we show how internal solitary
waves evolve with time and how well satellite observations and model results agree. top
Ambar, I., and J. Dias: Coastal Upwelling Systems in the North-Eastern Atlantic Ocean
The Sea Surface Temperature (SST) distribution of the subtropical
North Atlantic shows a clear contrast between the western and
eastern borders, the latter showing lower SSTs off the Iberia and NW Africa
coasts. This asymmetry is due not only to the advection of cold waters
by the southward branch of the large-scale subtropical gyre but also to the
upwelled cold subsurface waters associated to the wind-induced coastal
divergence. The upwelling occurring off the western coast of Iberia has a
seasonal character associated with the predominant northerly winds during
the summer months – July, August and September – whereas, further south
(20-25ºN), the upwelling off the NW African coast is a permanent phenomenon
driven by the trade winds. Since SST distributions show a strong
imprint connected to the upwelling occurrence, infrared remote sensing is
a widely used tool for the study of this phenomenon and of the respective
time-space variability. Furthermore, the upwelling-induced productivity of
the upper ocean is also detectable by remote sensing in the visible domain,
and so complements the information obtained through the SST data. The
present paper reviews the main aspects, mostly based in satellite observations,
related to the physical and biological characteristics of the upwelling
off Iberia and to their seasonal and interannual changes. top
Askne, J., and W. Dierking: Sea Ice Assessment by Means of Synthetic Aperture Radar
Large areas of the polar regions are covered by of sea ice. Sea ice has
a profound impact on the solar albedo of the polar regions, on the exchange
of heat, momentum, and matter between the ocean and the atmosphere, and
on deep ocean circulation. It has also a strong influence on marine
operations such as ship traffic, fisheries, or oil and gas exploration.
In this chapter, methods of sea ice monitoring using synthetic aperture
radar are addressed. We introduce parameters observable from satellite or
from airplane that are needed to characterize the physical properties of
a sea ice cover such as ice concentration, drift, ice type distribution,
or deformation. The relevance of sea ice properties such as surface
roughness or volume structure for the mechanisms of radar scattering are
explained. We discuss advantages and limitations of different SAR
configurations for sea ice observations, focussing on radar frequency,
polarization, incidence angle, spatial resolution, swath width, and orbit
repeat cycle. The use of SAR imagery in operational sea ice mapping for
guidance of marine traffic is examined. We present examples for extracting
parameters relevant for climate research such as the timing and length of
the melt season, or development of polynyas. Other topics discussed are
the problem of retrieving sea ice thickness from SAR data, and validation
and improvements of numerical models used for simulating the dynamics of
the sea ice cover. top
Barale, V.: The European Marginal and Enclosed Seas: an Overview
The enclosed and marginal seas surrounding the European continent exhibit a wide
spectrum of environmental traits, ranging from sub-polar to sub-tropical climates,
from shallow continental shelves to deep oceanic basins, from pristine marine reserves
to regions impacted by countless economic and recreational activities. This introduction
will be devoted to a brief oceanographic overview of the main European Seas: the NE
Atlantic Ocean; the Norwegian, Greenland and Barents Seas; the North Sea and the Baltic
Sea; the Mediterranean Sea, the Black Sea and the Caspian Sea. In each case, concise
notes will be provided to cover basin description, climate, bathymetry, water balance,
exchanges and circulation, main ecological traits, anthropogenic impact and environmental
concerns. Common features, profound diversities and peculiarities will be highlighted. top
Berthon, J.-F., F. Mélin, and G. Zibordi: Ocean Colour Remote Sensing of the Optically Complex European Seas
Since the end of the 70's and the arrival of the 'Coastal Zone Colour Scanner' sensor, the
exploitation of ocean colour remote sensing data in terms of atmospheric and marine products,
considerably improved. The reduction in the uncertainty of the final derived products
benefited from improvements in the sensors instrumental characteristics but also in the
processing models and algorithms.
However, important uncertainties still persist for the retrieval of these marine products,
like the phytoplankton chlorophyll a, in particular in the coastal areas where a typical,
although not exclusive, absence of covariance among the main seawater components occurs.
In these waters, the sources of particulate and dissolved materials are numerous (biological
production, rivers outflow, bottom re-suspension, atmospheric deposition, …) and contribute
to increase the uncertainty associated with the inversion of the surface optical signal. The
proximity of the continent also induces the presence of specific aerosols (e.g., absorbing
aerosols, desert dust, …) making the atmospheric correction procedure more challenging.
A considerable fraction of the European seas is located in the "coastal zone" and, from
the Baltic Sea to the Black Sea, and including the Mediterranean Sea, presents a great
variability of optical behaviour.
After a brief reminder of the general principles of ocean colour remote sensing, the main
atmospheric and marine optical characteristics of the European basins will be here presented
and compared, and a review of the presently proposed methods for the interpretation of ocean
colour data in these waters will be made. top
Brockmann, C., and K. Stelzer: Application of Optical Remote Sensing in Intertidal Flats
Driven by the increasing needs for cost effective methods of large scale mapping
of various parameters in the coastal zone and particularly in inter-tidal flats,
remote sensing techniques in different fields of application has been recently
developed in the framework of EU co-funded and user driven projects. These
remote sensing techniques will optimise operational monitoring programs in
order to fulfil the requirements of directives such as the Water Framework
Directive or the Fauna Flora Habitat Directive. Traditionally, aerial
photographs are used within the monitoring of inter-tidal flats for a long
period. This interpretation is now amended by automated and objective methods
that are not so strongly user depended. Information concerning different
components of tidal flats, such as the sediment, macro- and microphytes and
blue mussel beds can be obtained by applying different methods to optical
remotely sensed data (e.g. atmospheric correction, Linear Spectral Unmixing,
Decision Tree Classification and Labelling). Quantitative estimates of their
position and areal cover can be retrieved, from which information concerning
change and development phenomena can be deduced. Landsat images provide a good
overview of larger tidal flat areas, however, when more detailed spatial
information is required, airborne remote sensing measurements should be used.
In-situ measurement programs can indeed be optimised by combining them with
remote sensing techniques, and to also highlight areas with greater change
or areas which should be under special observation. Remote sensing is not a
substitution for in-situ measurements, but rather complements other measurements
in operational monitoring programs, as will be demonstrated. top
Cipollini, P., S. Vignudelli, F. Lyard, et al.: 15 Years of Altimetry at Various Scales over the Mediterranean
In this paper we review the main findings from the application of satellite
altimetry to the monitoring of ocean circulation over the Mediterranean Sea at
a wide range of spatial scales (coastal to basin) and temporal scales (seasonal
to decadal).
The early studies in the mid 1990s were based on a single altimetric mission,
therefore suffering from sampling limitations that aliased a significant part
of the mesoscale circulation and of its variability. However these pioneering
studies demonstrated the potential of altimetry over the basin. A much more
successful approach has emerged in the second half of the 1990s with the merging
of data from different missions. This has been made possible by both the improvement
in orbit determination and geophysical and instrumental corrections for the ERS
satellites and the development of techniques for the optimal merging and interpolation
of the multisatellite data. We discuss some examples of how altimeter-based research
on the basin-scale and mesoscale circulation and their seasonal, interannual and
decadal variability has improved the understanding of Mediterranean dynamics. We
also review some studies where along-track altimeter data have been combined with
hydrographic data in specific regions in order to solve oceanographic questions,
for instance on what drives the flow in the Corsica Channel.
A section on coastal altimetry describes frontier research aiming at recovering as
much information as possible near the coast, how this has been tested in a pilot
area of the Northwestern Mediterranean and the plans for future activities to
promote altimetry to the rank of operational record for coastal monitoring. top
Donlon, C.: he Next Generation of Multi-Sensor Merged Sea Surface Temperature Data sets for Europe
Sea surface temperature (SST) measured from Earth Observation Satellites in considerable
spatial detail and at high frequency, is increasingly required for use in the context of
operational monitoring and forecasting of the ocean, for assimilation into coupled
ocean-atmosphere model systems and for applications in short-term numerical weather
prediction and longer term climate change detection. Currently there are many different
SST data sets available derived from satellite systems. But, scientists and operational
agencies alike are presented with a bewildering set of options in terms of SST product
content, coverage, spatial resolution, timeliness, format and accuracy.
This paper reviews these next generation SST systems and data products now available for
the European area. The GODAE High Resolution SST Pilot Project (GHRSST-PP, see
http://www.ghrsst-pp.org) has developed an internationally agreed framework called the
Regional/Global Task Sharing Framework (R/GTS) that provides integrated satellite derived
SST products in a common format from a variety of operational international agencies and
data providers in real time. L2 input SST data products are processed at each contributing
agency following a Detailed Processing Specification agreed by the GHRSST-PP International
Science Team. The output L2P products contain dynamic flags and uncertainty estimates for
each SST measurement that allow users to quality control SST data prior to direct use or
as part of data analysis/assimilation systems. L2P auxiliary fields allow dynamic flagging
of oceanographic phenomena such as diurnal stratification (both warm layer and cool-skin),
aerosol contamination and sea ice.
Based on GHRSST-PP L2P data products, a new generation of high-resolution (better than 10 km
and ~6 hourly) SST data products are now available for European waters from operational
systems derived by combining readily available but complementary Level-2 (L2) satellite and
in situ observations in real time to improve spatial coverage, temporal resolution, cross-sensor
calibration stability and SST product accuracy. In particular, 2km maps of the Mediterranean
Sea and 1/20 degree (~6km) global maps are provided every day from European systems. top
Dransfeld, S.: Current Tracking in the Mediterranean Sea using
Thermal Satellite Imagery
Infra-red images representing the thermal state of the ocean surface may be
used to track ocean currents with feature-tracking algorithms that identify
and follow temperature gradients and hence represent advective surface
motion. One of these techniques, the Maximum Cross Correlation (MCC)
technique, is based on a comparison of individual subscenes of sequential
images, to estimate where a feature has moved from one image to the next.
It has distinct advantages compared to alternative feature tracking algorithms
such as its simplicity and robustness. Previous research has shown
it to achieve a precision of 0.08 to 0.20 m/s rms. This study focuses on surface
currents in the central Mediterranean Sea by analysing sequential Advanced
Very High Resolution Radiometer (AVHRR) local area coverage
(LAC) 1.1 km resolution images from June 2003. Most attention is placed
onto the presentation of the method, the results and the main
ad/disadvantages of using an MCC approach. top
Ferraro, G., A. Bernardini, B. Bulgarelli, S. Meyer-Roux,
O. Muellenhoff, D. Tarchi, and K. Topouzelis: The Use of Satellite Imagery from Archives to Monitor Oil Spills in the Mediterranean Sea
Accidental pollution at sea can be reduced but never completely
eliminated, on the other side, deliberate illegal discharges from ships can
indeed be reduced by the strict enforcement of existing regulations and the
control, monitoring and surveillance of maritime traffic. Notwithstanding,
operational oil discharges is a common practice and represents the main
source of marine pollution from ships. Consequently, JRC has focused its
attention on the need to monitor in the long term the problem of sea-based
oil pollution in all European seas. For this reason, JRC has collected aerial
surveillance data and satellite imagery from different actors and archives,
even if the data for the seas around Europe are not homogeneous. In this
paper, JRC intends to present the first results of the analysis of the created
database on oil spills for the Mediterranean Sea. In conclusion, the long
term oil spill monitoring is the key instrument to assess the implementation
of maritime transport regulation such as the Directives on port reception
facilities and on ship-source pollution and can be seen as an environmental
indicator of the European Seas. top
Font, J., and A. Camps: Microwave Aperture Synthesis Radiometry:
Paving the Path for Sea Surface Salinity Measurement from Space
This chapter summarizes the main objectives and characteristics
of the ESA’s SMOS mission and its remote sensing applications. The
SMOS payload is MIRAS, a new type of instrument in Earth observation:
the first two-dimensional aperture synthesis interferometric radiometer. It
operates at L-band, has multi-angular and multi-look imaging capabilities,
and can be operated in dual-polarization or full-polarimetric modes. Due to
its novelty, the principles of operation, imaging characteristics and its main
performance parameters (spatial resolution and radiometric sensitivity and
accuracy) are described, as well as the approach selected in the retrieval
algorithms of sea surface salinity. top
Gade, M.: Satellite Remote Sensing of Coastal Discharge Plumes in Europe
Coastal discharge plumes are often visible on satellite imagery acquired by optical,
infrared, and microwave sensors, because they may change the local chlorophyll
content, the sea surface temperature (SST), or carry surface-active substances,
like hydrocarbons. This paper provides an overview of different kinds of
discharge plumes and demonstrates the ability of satellite-borne sensors to
monitor them. The chosen test site is the Spanish Costa Dorada in the north-western
Mediterranean, where we observed manifestations of a river run-off and an industrial
waste (cooling) water plume. We demonstrate that the combination of satellite data
from different sensors (i.e., data fusion) may help to interpret the observed features
better and to specify the impact of coastal run-off on the local ecosystem. top
Greidanus, H.: Ship Detection by Satellite Imaging
The particular characteristics of polar orbiting satellite images strongly impact on the
way they can be used for vessel surveillance purposes, and dictate the scope of their
applications. These lie in fisheries control, pollution risk analysis and control, and
maritime safety and security. Satellite SAR data are particularly useful for surveying
large, outlying areas for vessel traffic, and for long term monitoring of sensitive areas.
The typical signature of a vessel in a wide area ocean image (usually, scan-SAR) is a
compact bright target with little structure. In higher resolution images (8 m at best)
the ship's outline and structure may be defined, but only at low sea states; the ship's
motion on the waves quickly causes severe azimuth smearing, precluding a reliable size
estimate and thereby a classification. VHR optical images provide much better capabilities
in that respect, but their sensitivity to clouds, limited footprint and higher cost per
km2 mostly limit their use to the surveying of localised small areas. Vessels have to be
detected against the background of sea clutter, necessitating the use of a threshold
leading to a limited detection rate (weak targets are missed because they fall below the
threshold) and false alarms (strong sea clutter peaks reach above the threshold). Vessel
detectability depends strongly on ambient parameters such as sea state and the occurrence
of ocean surface features; system and imaging parameters such as resolution, polarization,
incidence and aspect angle; and target parameters such as ship size and material. Moving
ships cause a wake, which is visible in SAR images, and this may be used to aid detection
and to extract information about target speed and heading. SAR parameters favourable to
ship detection (HH polarization, shallow incidence) are unfortunately not optimal for wake
imaging. ENVISAT-ASAR shows that also HV polarisation is useful for ship detection,
particularly at steep incidence. top
Gurgel, K.-W., and T. Schlick: Fundamentals and Applications of Land-based Radar Techniques for Monitoring the Coastal Zone
Land-based Radar Techniques have been developed for some 30 years and are now available
for operational monitoring services. This paper describes the fundamentals and possible
applications of shore-based High-Frequency (HF) radars, which are operated in the 5 to
30 MHz frequency range and use ground-wave propagation mode of the electromagnetic waves.
Depending on the operating frequency selected, working ranges up to 200 km and a spatial
resolution down to 300 m can be achieved. The parameters measured include surface current
fields, wave directional spectra and wind direction. The performance of these systems has
been evaluated within several experiments. In addition to these oceanographic applications,
an HF radar can also be used to track ship locations from the same backscatter data sets,
i.e. simultaneously to the oceanographic parameters. Besides the HF radars, X-band radars
can be operated from shore. These type of systems are described within an own section of
this book. top
Hoogeboom, P., and L. Lidicky: Introduction to Microwave Active Techniques and Backscatter properties
Microwave measurement techniques are being used in remote sensing due to their all-weather,
day and night availability and, what is especially important for satellite systems over
Northern Europe, for their ability to penetrate clouds. This paper presents an introduction
to active microwave techniques used in sea remote sensing. The focus is on radar systems.
As an introduction to radar systems, ranging and azimuth positioning are discussed and
important radar parameters introduced.
Two-dimensional radar systems for remote sensing applications appear in several forms:
Ground rotating ships radars are used for wave- and oil spill monitoring. Systems employing
linearly translating antennas are used in Side Looking Radar (including Synthetic Aperture Radar)
systems and Scatterometers. Their principles, properties, advantages, and constraints will be
discussed. Several basic processing techniques will be introduced.
Special attention will be devoted to SAR systems, both air- and spaceborne. SAR systems have
a resolution which is independent of the wavelength and the range. A value for the maximum
resolution is derived. Up-to-date concepts of two-dimensional SAR processing will be introduced.
The cause of image peculiarities like azimuth ambiguities and azimuth displacement of moving
ships are explained. The concept of modern polarimetric SAR systems is introduced and some
examples of current systems are given.
Next, basic radar backscatter theory will be introduced and its influence to scattering
properties of a sea surface described. Topics such as polarization and Bragg scattering
will be introduced. The angular dependence of radar backscatter and its dependence on
windspeed are discussed. The theory for determination of the windvector from radar measurements
is treated. Attention is paid to decorrelation of radar returns. Finally, various backscatter
modulation processes, e.g. from seawaves and oil spills, are discussed. top
Horstmann, J.: High Resolution Wind Field Retrieval from Synthetic Aperture Radar
A methodology for retrieving high resolution ocean surface wind fields from satellite borne
synthetic aperture radar (SAR) data is introduced and validated. The algorithm is suited for
ocean SAR data, which were acquired at C-band of either vertical (VV) or horizontal (HH)
polarization at moderate incidence angles. Wind directions are extracted from wind induced
streaks that are visible in SAR images and that are very well aligned with the mean surface
wind direction. To extract the orientation of these streaks an algorithm based on the
derivation of local gradients is utilized. Ocean surface wind speeds are derived from the
normalized radar cross section and image geometry of the SAR images, together with the local
SAR-retrieved wind direction. Therefore, several C-band models (CmodIfr2, Cmod4, and Cmod5)
are available, which were developed for VV polarization and have to be extended for HH
polarization. To compare the different algorithms and C-band models as well as demonstrate
their applicability, SAR retrieved wind fields of the North Sea are compared to numerical
model results considering advanced SAR data from the European satellite ENVISAT.
top
Kern, S., S. Andersen, F. Ardhuin, R. Ezraty, G. Heygster, L. Kaleschke, and G. Spreen: Sea Ice Parameters from Microwave Radiometry
Microwave radiometry has been playing a key role for the observation of sea ice parameters
at global scale for almost three decades now. Among these parameters are sea ice concentration,
drift, and type. Time series of these parameters date back to 1972, 1978, and 1978, respectively.
Recent advances in satellite technology and algorithm development enable to further expand the
parameter range, to refine the spatial resolution, and to apply microwave radiometry at regional
scale also, such as the Baltic Sea. The present paper describes briefly key aspects of the
relevant theory, data acquisition and available retrieval techniques. It gives examples for
advances in algorithm development, evaluation and application. top
Kopelevich, O.V., V.I. Burenkov, and S.V. Sheberstov: Case studies of optical remote sensing in the Barents Sea, Black Sea, and Caspian Sea
The Barents, Black and Caspian Seas are considered as an example of the seas
with high freshwater inflow. All of them are classified with Case 2 waters; an additional
problem with atmospheric correction of satellite ocean color data exists in
the Barents Sea through its high latitude position. Optical remote sensing of these
seas requires modified processing algorithms regionally adapted. Such algorithms
have been developed on the basis of in situ measured data. Similarity and discrepancy
between the seas in the factors determining seawater optical characteristics
and in their effects on the bio-optical algorithms are analyzed.
In the Black Sea and in the Middle Barents coccolithophore blooms revealed
from satellite ocean color data have been confirmed by field studies; in the Caspian
Sea a coccolithophore bloom has not been reported yet. An interesting feature
of the Black Sea is the enhanced values of the particle backscattering coefficient
observed in June year after year. The joint analysis of satellite and in situ measured
data leads us to conclusion that this phenomenon may be caused both by a
coccolithophore bloom and a river runoff. In the Caspian Sea satellite data displayed
sharp increase of chlorophyll concentration and of the particle backscattering
in July-August 2001 attributed to a consequence of invasion of the ctenophore
Mnepiopsis leidyi, and its effect has been traced in succeeding years. top
Lavender, S.J., et al.: The Seasonal and Longer Term Variations in the Phytoplankton of the North Eastern Atlantic Ocean: from the Irish Sea to the Bay of Biscay
This paper will primarily utilize the SeaWiFS visible spectral radiometry
(previously called ocean colour) time series (almost 9 years when this paper
will be submitted) to look at the variation of optical properties within the
NE Atlantic. Recent work has highlighted that there was a shift in the Central
Northeast Atlantic (Raitsos et. al., 2005) and North Sea (McQuatters-Gollop
et. al., Submitted) chlorophyll levels during the 1980's. The NE Atlantic
(from the Irish Sea to Bay of Biscay) will be studied in greater detail by
splitting it up into bio-geo-graphical provinces, and the analysis will be
extended from just chlorophyll to the optical properties (absorption and
scattering). Although remote sensing can be both a cost effective and long
term method for monitoring, it needs to be combined with in-situ sampling and
numerical modelling so that interactions can be understood. Therefore, the
analysis will include remote sensing data (derived optical properties and Sea
Surface Temperature) together with available in-situ datasets and the results
of models such as the NCEP/NCAR reanalysis so that the variations can be
explained in terms of the driving factors. top
Lavrova, O., M. Mityagina, T. Bocharova, and M. Gade: Multi-Sensor Observation of Meso-Scale Features in European Coastal Waters
Results of long-term multi-sensor observations of coastal zones
in the Baltic and Black Seas are discussed. The study is based on remote
sensing data acquired over these regions by the ERS-2 SAR, Envisat
ASAR, Terra and Aqua MODIS, and NOAA AVHRR. The data were
analysed to investigate coastal water circulations, in particular the
occurrence, evolution, and drift of small- and meso-scale vortex structures,
because their understanding is crucial for the knowledge of the
mechanisms that determine mixing and circulation processes in the coastal
zone. To a large extent, these mechanisms determine the coastal zone’s
ecological, hydrodynamic and meteorological state, whose constant
monitoring is vital for these densely populated regions with their welldeveloped
industry and agriculture and a rapidly growing tourist sector.
SST fields derived from AVHRR data were used to observe meso-scale
water dynamics. Using MODIS SST and ocean colour data we were able
to highlight various meso- and small-scale water dynamics features, such
as currents, eddies, dipoles, jets, filaments, and river plumes. Surfactants
of natural and artificial origin are often encountered in coastal waters, and
their signatures on SAR images help the detection of small- and mesoscale
surface currents and vortex structures. top
Pozdnyakov, D., A. Korosov, and L. Pettersson: Combined visible and infrared remote sensing of the White Sea biogeochemistry and hydrology
A new operational non-satellite-specific algorithm for a simultaneous retrieval
of contents of phytoplankton chlorophyll (chl), suspended minerals (sm) and dissolved
organic carbpon (doc) from space sensor data, was employed to monitor
the surface expressions of some biotic and abiotic processes in the White Sea
(WS). A special technique has been developed to reconstruct the seasonal variations
of the above substances in pixels occasionally masked by cloudiness. The
developed software package provided a means to obtain the series of intraannual
spatial and temporal variations of chl, sm, doc and sea surface temperature (SST)
throughout the WS from SeaWiFS and AVHRR, respectively. The observed variations
are controlled by a) the dynamics of water turbidity and opacity due to seasonal
variations in the content of sm and doc driven by the river discharge varying
influence, and b) thermohydrodynamic processes encompassing water density currents,
tides, upwellings, fronts, etc. top
Romeiser, R., and H. Runge: Current measurements in coastal waters and rivers by along-track InSAR
The along-track interferometric synthetic aperture radar (alongtrack
InSAR, ATI) technique permits a direct high-resolution imaging of
ocean surface current fields from aircraft and satellites. With several airborne
ATI experiments and a first demonstration of current measurements
from space with data from the Shuttle Radar Topography Mission (SRTM)
in February 2000, European scientists have built up a leading expertise in
this field, and the upcoming German satellite TerraSAR-X will be the first
to offer ATI capabilities during a longer period. We give an overview of
ATI fundamentals, SRTM results, predicted current measuring capabilities
of TerraSAR-X, the potential for further improvements, and promising applications
in coastal waters and rivers. top
Ruddick, K., et al.: Optical Remote Sensing Applications in the North Sea
The North Sea is a marginal shelf sea. Depths range from less than 50m for much of the
Southern Bight to more than 300m in the Norwegian coastal waters with intermediate depths
in the Western Channel, Celtic Seas and the Northern North Sea. Physical oceanography of
the region is influenced by the strong tides and by frequent wind events. Water masses
range from inflowing oceanic water to the various coastal waters affected by freshwater
discharges from rivers and from the Baltic Sea. The catchment area of the river basins
is highly populated and industrialized particularly for nutrient-enriched rivers discharging
along the continental coast from France to Denmark. Economic exploitation of the coastal
areas is intense with activities including tourism, fisheries, aquaculture, wind farms,
dredging for navigation, etc. Environmental problems of relevance to optical remote
sensing include eutrophication and harmful algae blooms, geomorphology changes caused
by sediment transport, and dramatic reductions in stocks of certain commercial fish.
Optical water types vary considerably over the region and by season, covering all
combinations of high/low concentrations of total suspended matter, chlorophyll a and
coloured dissolved organic matter. Near real time remote sensing of the region is now
standard and historical satellite data archives back to 1997 allow characterisation of
long-term averages as well as seasonal and interannual variability. Processing algorithms
have developed significantly but problems remain, for example, for atmospheric correction
in coastal waters and for chlorophyll a retrieval in high yellow substance waters. This
chapter describes a number of current applications of optical remote sensing in the North
Sea including eutrophication assessment, algae bloom detection and suspended matter mapping
as support for sediment transport problems, etc. Emerging and future applications are also
discussed. top
Sandven, S.: Sea Ice Monitoring Using a Multisensor Approach
Advances in satellite remote sensing of sea ice and icebergs in Arctic regions are described in
case studies showing the benefits of using multisensor observations. It is demonstrated how
Synthetic Aperture Radar (SAR) used in combination with optical images can improve discrimination
of open water, nilas, young ice and three gradations of deformed first-year ice. The classification
method is based on multisensor data fusion and neural network, where in situ observations were used
for training of the al-gorithm. Synergetic use of scatterometer and passive microwave (PMW) data is
well-established to estimate large scale ice motion, but in straits and marginal seas more detailed
ice drift data are needed. In the Fram Strait SAR images from ENVISAT have been used to estimate ice
drift and ice area flux since early 2004. It is demonstrated that SAR wideswath images can provide
more accurate and higher-resolution ice drift vectors compared to scatterometer and PMW data. Methods
for retrieval of thickness for thin ice are available using thermal infrared, passive microwave and
SAR data, but these methods are research-oriented and not used in regular monitor-ing. Laser and radar
altimeter measurements from satellites have shown promising capability to observe sea ice freeboard
and thickness for ice thicker than about one meter. Such data used in combination with ice drift and
ice types will provide new estimates of ice volume variability and fluxes. SAR and optical data have
also been used to observe icebergs in the Barents Sea. The two data types are complementary and can
improve iceberg detection if they are used in combination. top
Santoleri, R., S. Marullo, and B. Buongiorno Nardelli: Observing the Mediterranean Sea from Space: Ocean Colour Algorithms and Chlorophyll Variability
In the last years, the rapid development of satellite technology has led to noticeable
progress in our knowledge of the physical/biological characteristics of Mediterranean Sea.
This paper will present the major and more recent contributions of the remote sensing in the
visible part of the spectrum (and of concurrent, complementary data collected by thermal
infrared and microwave sensors) to this knowledge. The paper will review: (1) the effort to
estimate the uncertainties and to develop regional algorithms to measure chlorophyll
concentration, or primary production, improving the ocean colour data quality; (2) the
impact of the SeaWiFS observation on the knowledge of the seasonal and inter-annual
variability of Mediterranean phytoplankton blooms; (3) the contribution of ocean colour
(and sea surface temperature) satellite data time series to detect environmental changes
and trends in the basin; (4) the promising use of ocean colour (and altimeter) data to
reconstruct the subsurface structure of the water column. Finally, the paper will discuss
the impact of optical remote sensing in operational oceanography of the Mediterranean Sea. top
Siegel, H., and M. Gerth: Optical Remote Sensing Applications in the Enclosed Baltic Sea
The Baltic Sea is a marginal sea with a limited water exchange with the
North Sea over the Skagerrak, Kattegat and the Danish Straits. A high freshwater
supply into the Baltic Sea result in a positive water balance and combined
with a sporadic inflow of high saline waters from the North Sea it generate a
permanent haline stratification. The warming phase in spring stabilises the
surface layer by thermal stratification and delivers the starting condition
for the spring bloom. After the depletion of inorganic nitrogen and a stagnation
period in late spring to early summer nitrogen-fixating cyanobacteria develop.
The intensity of the toxic cyanobacteria blooms depend strongly on the course
of the summer, e.g. concerning the meteorological conditions. Coastal discharges
and the phytoplankton blooms influencing the variation of optically active water
constituents are the main topics for the application of ocean colour remote sensing
data in the Baltic Sea. Satellite data of different spectral and spatial resolution
have been used to study these processes. Ocean colour sensors like CZCS, MOS,
SeaWiFS, MODIS and MERIS were implemented for investigations in the entire Baltic
Sea. Additionally, data of sensors with high spatial resolution from the Indian
satellite IRS and Landsat are applied for detailed studies of phytoplankton blooms,
river plumes and coastal processes. Information on environmental conditions were
derived from the American weather satellite sensor NOAA-AVHRR and implemented in
interdisciplinary investigations. Near real-time satellite data are used to support
ship cruises and local authorities during special events like river flooding or
extreme cyanobacteria bloom to gather the spreading and the potential endangered
coastal regions. top
da Silva, J.C.B.: SAR Observation of Rip Currents off the Portuguese Coast
The role of Synthetic Aperture Radar as an important tool to observe the coastal
zones is now well established. However, despite the numerous SAR applications
developed to study the coastal zone, the observation of very near-shore small
scale processes, such as rip currents, has not received enough attention from
the SAR scientific community so far. Rip currents are near-shore cellular
circulations that can be described as narrow, jet-like and seaward directed
flows. These flows originate close to the shoreline and may be a result of
alongshore variations in the surface wave field. Observation of rip currents
is important in coastal engineering studies because they can cause a seaward
transport of beach sand and thus change beach morphology. Since rip currents
are an efficient mechanism for exchange of near-shore and offshore water,
they are important for across shore mixing of heat, nutrients, pollutants
and biological species. Rip currents are particularly dangerous for beachgoers,
as swimmers may be caught in the strong offshore-directed currents and flushed
out to sea. Most of water rescues on surf beaches are due to rip currents,
and so it is important to know where the most threatening rips can be found
to inform life-guards. We have been able to identify signatures of rip
currents in a series of SAR images. The images correspond to low wind speed
conditions, and according to the wind direction and rip strength, the rip
signatures may display different type of image contrasts. The SAR rip
signatures presented in this chapter are consistent with rip current morphology,
and we have been able to explain them with a wind contrast model based on a
simple first-order Bragg scattering theory. Because new SAR missions (such
as Terrasar-X) are equipped with finer resolution modes, SAR observations
could significantly improve our capabilities to observe rip currents from
satellite. top
Solberg, A.S., and C. Brekke: Oil Spill Detection in European Waters: Approaches, Algorithms and Guidelines for use
The combined use of satellite-based SAR images and aircraft surveillance
flights is a cost effective way to monitor illegal oil spills in large ocean
areas and catch the polluters. SAR images enables covering large areas, but
aircraft observations are needed to prosecute the polluter, and in certain
cases to verify the oil spill. Oil spills are visible in the SAR images as
dark spots because the oil dampens the capillary waves, but other natural
phenomena also create dark patches in the SAR image. A major part of the
oil spill detection problem is to distinguish between oil spills and look-alikes.
Automatic detection of oil spills has proven to be an interesting alternative
to manual detection. We present an overview of algorithms for automatic
detection, and discuss their potential compared to manual inspection as
part of an operational oil spill detection framework. We discuss limitations
of satellite imaging of oil spills compared to aircraft monitoring. Experimental
results show that automatic algorithms can perform well compared to manual
detection, both in terms of accuracy in detecting verified oil slicks, false
alarm ratio, and they can also speed up the image analysis process compared
to fully manual services. top
Skou, N.: Microwave Passive Techniques: Radiometers and Radiometry in General
The microwave radiometer system measures, within its bandwidth, the naturally emitted
radiation - the brightness temperature - of substances within its antenna's field
of view. Thus a radiometer is really a sensitive and calibrated microwave receiver.
The radiometer system will very often be configured as an imaging system on a
spacecraft for example. This normally implies scanning the antenna. Then there
are certain relationships (or even conflicts) between achievable radiometric
sensitivity / ground resolution, achievable ground resolution / antenna size,
scanning antenna / spacecraft stability. In many cases good compromises have been
reached as evident recalling the many successful missions throughout the recent
30 years. But in some cases the situation calls for special solutions like the
synthetic aperture radiometer technique. Here a large antenna, that would be
difficult to scan, is replaced by many small antennas and advanced interferometric
processing to yield an imaging system without scanning. Calibration establishes
the relation between instrument output and the input brightness temperature.
The radiometer system might be single or dual polarized (horizontal and vertical)
- or even be polarimetric, i.e. measure all 4 Stokes parameters, thus providing
additional geophysical information at any given frequency. However, in an attempt
to measure properties of the sea from space, the intervening atmosphere will
disturb the process, and corrections might be required (radiative transfer).
Also, at some frequencies and for some applications, the Faraday rotation in
the Ionosphere must be taken into account. Typical applications of microwave
radiometry concerning oceans are: sea salinity, sea surface temperature, wind
speed and direction, sea ice detection and classification.
top
Stoffelen, A.: Scatterometer Applications in the European Seas
Scatterometers have been flown continuously from 1991 until today and the
application of the backscatter data in a wide variety of applications has
emerged: wind fields for nowcasting and Numerical Weather Prediction (NWP),
sea ice information for ice centres, and soil moisture assessment for
meteorological and hydrological applications.
Scatterometer wind fields provide a wealth of detail in the marginal and
enclosed seas surrounding the European continent. Whereas other observing
systems or NWP fields provide reasonable temporal sampling, these systems
lack the spatial resolution necessary to identify mesoscale developments,
and its associated humidity convergence. Moreover, with a suitable choice of
wavelength, scatterometer wind fields are available in all weather
conditions, this in contradiction to passive satellite remote sensing
techniques for near-surface wind. As such, scatterometer winds have proven
useful for the improved prediction of extreme weather phenomena, such as for
example tropical cyclones. With the launch of EUMETSAT's MetOp-A, the
scatterometer era may be extended by another 15 years. top
Taupier-Letage, I., and C. Millot: The role of the thermal infrared images in the revision of the surface circulation schema in the eastern basin of the Mediterranean
Although the first schema of the surface circulation (water of Atlantic origin:
AW) in the Mediterranean dates back to the early 1910s, one century later there
is still a fierce debate on the path of AW in the eastern basin. The historical
schema shows a circulation counterclockwise at basin scale (same as in the western
basin), with AW flowing in its southern part as a broad flow off Libya and Egypt.
Followers up to the 1960-70s supported this representation, but the large POEM
experiment in ~1985-1995 issued a schema where the main path of AW is a jet
meandering in the central parts of the basin (the so-called "Mid-Mediterranean
Jet"). This latter schema prevails presently. However that representation has
been questioned. Firstly because IR images display analogous features in both
basins: the currents along the southern continental slopes are unstable and
generate mesoscale eddies (which implies a high spatio-temporal variability).
And secondly because in situ observations lack in the southern part of the
eastern basin. A similar controversy about the path of the Levantine Intermediate
Water in the southern part of the western basin has been recently solved, by
combining satellite (IR images mainly) and in situ observations. This definitely
validated the use of IR signatures to infer marine circulation features.
Therefore the question of the AW path in the eastern basin was first addressed
analysing a time series of ~1000 IR images spanning 4 years (1996-2000). The
resulting hypothesis was that the northern edges of successive mesoscale eddies
off Libya and Egypt must have been mistaken for the "MMJ". The second step was
to design an experiment at sea, with the sampling strategy defined upon reception
and analysis of IR images in near-real time on board, especially to locate the
eddies. The campaign EGYPT-1 (Eddies and GYres Paths Tracking, www.ifremer.fr/lobtln)
took place in April 2006, and both satellite and in situ observations confirm i)
that AW flows alongslope in the south, and ii) that the eddies created by the
instability of the current are responsible for spreading AW offshore. The IR
images (and ocean color as well) are thus an indispensable source of information
for oceanic circulation studies. top
Tsimplis, M.N., A.G.P.S. Shaw, A. Pascual, M. Marcos, M. Pasaric,
and L. Fenoglio-Marc: Can we Reconstruct the 20th Century Sea Level Variability in the Mediterranean Sea on the Basis of Recent Altimetric Measurements?
Altimetric records are used to extract the decadal sea level signal for the Mediterranean
Sea and its sub-basins. Significant differences are evident between the Eastern and
Western Mediterranean Sea. The spatial patterns derived by the use of Empirical
Orthogonal Functions (EOF) are then used to reconstruct sea level variability in
the Mediterranean Sea by combining these EOFs with the few available tide-gauges
at the coasts of the basin. Because it is not certain that the last 15 years, over
which altimetric measurements are available are typical of either the spatial or the
temporal variability of the region we explore the cross correlation across the basin
and compare it with tide -gauge correlations in time. In addition we also question
whether the reconstruction of the sea level for the past century based on data from
the last decade is at least as successful in describing the variance at the long tide
gauges as reconstructions based on previous decades. Finally we explore the frequency
variation in the decadal system and provide estimates of sea level variability for the
past century for areas in the southern part of the Mediterranean where no data presently
exist. top
Woolf, D.K., and C. Gommenginger: Applications of Radar Altimetry
Radar altimeters are among the more common satellite-borne Earth Observation
instruments with a long history including continuous data since 1991. They are
also exceptionally versatile providing information on sea level, ocean dynamics,
wind speed and a number of wave parameters. Radar altimetry is a "point" rather
than a "swath" instrument so that sampling resolution by a single altimeter is
relatively poor in both space and time. Also the sizeable footprint restricts
use of altimetry to greater than 10km from any coast, with some restrictions at
a greater distance. The sampling limitations do not negate the usefulness of
altimetry, either in isolation or in combination with other instruments or
modelling. Climatologies of sea level and wave parameters built from altimetry
provide a unique perspective on both a regional and global scale. Measurements
of individual storm events provide a test for both wave and storm-surge modelling
and could be useful in Near Real Time applications. New interpretations of
satellite altimeter waveforms and dual-frequency data are broadening the
geophysical applications of radar altimetry. top
Ziemer, F.: Wave and Current Observations by Ground Based X-Band RADAR
Wave and current observations by ground based X-band radar has reached a level
of operability that it has established among the tools in earth observation.
Mounted at coastal stations, ships or offshore rigs this type of instrument provides
parameter describing the dynamic field within the surrounding sea on a local scale
with a diameter of up to some nautical miles. The article will discuss the extraction
of the significant wave and current describing parameter. Beyond this it will give
insight in inverse modelling techniques to produce geo-coded maps of field parameter
like the local water depth or the local current vector to assess the bathymetry or
water flow rates through any cross section in rivers or coastal inlets. Additionally
this article will give details on recent developments using coherent radar to discover
small scaled dynamic features. For this the instrument was adapted to detect the phase
of a magnetron produced radar pulse to obtain the Doppler shifted frequencies from a
series of signals backscattered from the rough sea surface. It will be shown that by
this technique a more direct area covering observation of the dynamic in the upper
ocean and especially in shallow waters becomes feasible. top
People
Allan, Tom D.,
Satellite Observing Systems, Godalming, Surrey, United Kingdom Alpers, Werner,
Institut für Meereskunde, Universität Hamburg, Hamburg, Germany Ambar, Isabel,
Instituto de Oceanografia, Faculdade de Ciências da Universidade de Lisboa,
Lisbon, Portugal Askne, Jan,
Chalmers University, Gothenburg, Sweden Babichenko, Sergey,
Laser Diagnostic Instruments, Tallin, Estonia Barale, Vittorio,
Institute for Environment and Sustainability, Joint Research Centre of the EC,
Ispra (VA), Italy Berthon, Jean-Francois,
Institute for Environment and Sustainability, Joint Research Centre of the EC,
Ispra (VA), Italy Brockmann, Carsten,
Brockmann Consult, Geesthacht, Germany Cipollini, Paolo,
Laboratory for Satellite Oceanography, National Oceanography Centre, Southampton,
United Kingdom Donlon, Craig J.,
National Centre for Ocean Forecasting, Hadley Centre, UK Met Office,
Exeter, United Kingdom Dransfeld, Steffen,
Institut für Meereskunde, Universität Hamburg, Hamburg, Germany Ferraro, Guido,
Institute for the Protection and the Security of the Citizen, Joint Research Centre of the EC,
Ispra (VA), Italy Font, Jordi,
Consujo Superior de Investigaciones Cientificas, Instituto de Ciences del Mar,
Barcelona, Spain Gade, Martin,
Institut für Meereskunde, Universität Hamburg, Hamburg, Germany Gurgel, Klaus-Werner,
Institut für Meereskunde, Universität Hamburg, Hamburg, Germany Greidanus, Harm,
Institute for the Protection and the Security of the Citizen, Joint Research Centre of the EC,
Ispra (VA), Italy Hoogeboom, Peter,
IRCTR / Microwave Laboratory, Delft University of Technology, Delft, The Netherlands Horstmann, Jochen,
Institute for Coastal Research, GKSS Research Center, Geesthacht, Germany Kopelevich, Oleg Victorovich,
P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia Lavender, Samantha,
Marine Institute, University of Plymouth, Plymouth, Devon, United kingdom Lavrova, Olga Yur'evna,
Space Research Institute, Russian Academy of Sciences, Moscow, Russia Pozdnyakov, Dmitry,
Nansen International Environmental and Remote Sensing Centre, St. Petersburg, Russia Romeiser, Roland,
Institut für Meereskunde, Universität Hamburg, Hamburg, Germany Ruddick, Kevin,
Royal Belgian Institute of Natural Sciences, Brussels, Belgium Sandven, Stein,
Nansen Environmental and Remote Sensing Center (NERSC), Bergen, Norway Santoleri, Rosalia,
Istituto di Scienze dell'Atmosfera e del Clima, Roma, Italy Siegel, Herbert,
Baltic Sea Research Institute, Rostock-Warnemünde, Germany da Silva, Jose C.B.,
Institute of Oceanography and Department of Physics, University of Lisbon, Lisbon, Portugal Skou, Niels,
Ørsted DTU, Technical University of Denmark, Lyngby, Denmark Solberg, Anne,
Institutt for Informatikk, Oslo, Norway Stoffelen, Ad,
KNMI, De Bilt, The Netherlands Taupier-Letage, Isabelle,
Universite de la Mediterranee, Centre d'Oceanologie de Marseille, c/o IFREMER, La Seyne, France Tsimplis, Mikis N.,
Laboratory for Satellite Oceanography, National Oceanography Centre, Southampton,
United Kingdom Woolf, David K.,
Laboratory for Satellite Oceanography, National Oceanography Centre, Southampton,
United Kingdom Ziemer, Friedwart,
Institute for Coastal Research, GKSS Research Center, Geesthacht, Germany
Page maintained by Martin Gade - last update: 6 March 2007