1 Joint Research Centre of the European Commission, Ispra, Italy 2 Universität Hamburg, Hamburg, Germany
Contents
Barale and Gade
(Preface, 3 pp.)
Part 1: Introduction to Remote Sensing of the African Seas
Barale
(The African Marginal and Enclosed Seas: an Overview,
29 pp.)
Gower and King
(Satellite Water Colour Observations in African Seas,
23 pp.)
Hoepffner and Nykjaer
(Thermal Infrared (TIR) Remote Sensing and Sea Surface Temperature (SST) of marine and coastal waters around Africa,
19 pp.)
Alpers
(Remote sensing of African coastal waters using active microwaves instruments,
20 pp.)
Part 2: Western Africa Near-Coastal Waters
Weil et al.
(Mesoscale activity in the Canary Islands area as observed through complementary
remote sensing techniques,
22 pp.)
Ohde and Siegel
(Impacts of Saharan dust on marine environment in the area off Northwest Africa,
16 pp.)
Djagoua et al.
(Water constituents assessment at the Sassandra River mouth (Côte d'Ivoire): an outline based on remote sensing reflectances,
15 pp.)
Kostianoy et al.
(Oil pollution in coastal waters of Nigeria,
17 pp.)
Siegel et al.
(The upwelling area off Namibia, the northern part of the Benguela current system,
18 pp.)
Bernard and Pitcher
(Ocean Color Remote Sensing of Harmful Algal Blooms in the Benguela System,
19 pp.)
Alpers et al.
(Satellite observations of oceanic eddies around Africa,
25 pp.)
Part 3: Eastern Africa Near-Coastal Waters
Krug et al.
(Observing the Agulhas Current with Sea Surface Temperature and altimetry data: challenges and perspectives,
18 pp.)
Johannessen et al.
(Use of SAR data to monitor the greater Agulhas Current System,
13 pp.)
Magelhaes and da Silva
(Internal Solitary Waves system in the Mozambique Channel,
24 pp.)
Lehner et al.
(Ship surveillance with High Resolution TerraSAR-X Satellite in African Waters,
29 pp.)
Part 4: Marginal and Enclosed Water Bodies
Andrefouet
(Remote sensing of coral reefs and their environments in the Red Sea and Western Indian Ocean: research and management,
21 pp.)
Barale and Gade
(Basic Ecosystem Dynamics in the Red Sea as seen by Sundry Remote Sensing Techniques,
19 pp.)
Karimova and Gade
(Eddies in the Red Sea as seen by Satellite SAR Imagery,
22 pp.)
Ahmed and Barale
(Satellite Observations of Coastal and Enclosed Waters in northeastern Africa,
25 pp.)
Ballatore et al.
(Remote Sensing of African Lakes: A Review,
21 pp.)
Acronyms (7 pp.) Index
Abstracts
Ahmed, M., and V. Barale: Satellite Surveys of Lagoon and Coastal Waters in the Southeastern Mediterranean Sea
Satellite observations provide elements about the environmental status of the major lagoons in
northern Egypt (i.e. Lakes Maryut, Edku, Burullus, Manzala and Bardawil) and the adjacent marine
area off the Nile River delta, in the southwestern Mediterranean region. Examples are shown of data
collected by various sensors onboard the Landsat, Système Pour l'Observation de la Terre (SPOT) and
EgyptSat-1 satellite series, and by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). The remote
sensing-derived parameters (e.g. lagoon size, aquatic vegetation patterns and other water quality
parameters) allow to evaluate evolution and degradation of the near-coastal water bodies in the
last four decades. The basic ecosystem indicators delivered by the satellite surveys are considered
important contributions for the establishment of a sound decision-making process for environmental
management purposes, aiming to ensure protection of natural systems and sustainability of human
activities. top
Alpers, W.: Remote sensing of African coastal waters using active microwaves instruments
Active microwave instruments flown on satellites to remotely sense the ocean are the radar altimeter,
the scatterometer, and the Synthetic Aperture Radar (SAR). While radar altimeter data are mainly used
as input for general ocean circulation models and for wind and global wave forecast, scatterometer
and SAR data are well suited to investigate singular events in the marine boundary layer and in the
ocean. Examples of atmospheric and oceanic phenomena observed by scat-terometers and SARs over
African coastal waters are presented. Concerning at-mospheric phenomena, first near-surface wind
fields derived from scatterometer data acquired over a cylone in the Mozambique Channel and over a
wind front west of Morocco are presented. Then SAR images showing sea surface signatures of an
atmospheric front, atmospheric gravity waves and a wind jet are presented. Quantitative information
on the near-surface wind field is derived from two of the four SAR images shown. Concerning oceanic
phenomena, three SAR images are presented. The first two SAR images show sea surface signatures of
internal waves generated in the Strait of Gibraltar and at the Atlantic shelf west of Morocco and
the third one shows sea surface signatures of biogenic surface films in the upwelling region off
the coast of Senegal. top
Alpers, W., D, Dagorne and P. Brandt: Satellite observations of oceanic eddies around Africa
Oceanic eddies having scales from several hundred meters to several hundred kilometers are
ubiquitous phenomena in the World's ocean. This became evident only after they could be observed
from satellites and space shuttles. Here we present several images taken in different spectral
bands which show signatures of eddies of different spatial scales in sea areas around Africa.
In particular, we present a series of satellite images showing the propagation of a small-scale
cyclonic (cold) eddy generated at Cap-Vert at the coast of Senegal into the open ocean. We show
that this small-scale eddy transported nutrients from the Senegal upwelling region westward into
the oligotrophic North Atlantic thus giving rise to enhanced chlorophyll-a concentration there.
Since eddies are also areas of high fish population, knowledge of their position and properties
is of great importance for fishery. top
Andrefouet, S.: Remote sensing of coral reefs and their environments in the Red Sea and Western Indian Ocean: research and management
The Red Sea and the Western Indian Ocean regions offer a wide variety of coastal configurations,
including large areas of coral reefs. In regions that include both developed and developing countries,
coral reefs and the services they provide are critical for the livelihoods, economies and well being
of local commu-nities, while they are at risk due to both anthropogenic and natural threats. Coral
reefs also offer to scientific research a unique array of ecological and geological processes
specific to these regions. Both applied and fundamental aspects moti-vate conservation and management
projects. Satellite and airborne remote sensing has contributed to scientific and management projects
with a variety of sensors and products, including some of the earliest coral reef applications
worldwide 30 years ago. High spatial resolution geomorphology, bathymetry and habitat maps provide
a biophysical description of the reefs themselves. Oceanic fields, such as sea surface temperature
regime and their anomalies, quantify how coral reefs are exposed to weather and climate forcing.
The combined local and large scale spatial information help understand how coral reefs status and
processes vary across space and time. In particular, data products are increasingly combined to map
the resilience of coral reef and associated habitats, and to design conservation plans at different
spatial scales. However, both high-tech state-of-the-art and user-friendly remote sensing are still
not used as systematically as it could be, while most countries still need basic spatial information
consistent at national and international scales, such as habitat maps. Future applied developments
will need to address these gaps in priority products. At the same time, on-going research will continue
to refine local and regional products relevant for the science and the management of the Red Sea and
the Western Indian Ocean coral reefs and their environments. top
Ballatore, T.J., S.R. Bradt, L. Olaka, A. Cózar and S.A. Loiselle: Remote Sensing of African Lakes: A Review
The optical complexity and small size of inland waters make the application of remote sensing
more challenging than for the open ocean. However, in Africa, where in situ monitoring of
important water bodies is financially, institutionally and spatially constrained, there is
strong demand for remote sensing to fill the critical information gap. Here we review a wide
range of applications of both passive and active remote sensing to African lakes. The
applications fall into five main categories: (1) visible, NIR, thermal and microwave sensing
of lake area; (2) altimetric and gravimetric sensing of lake level; (3) thermal sensing of
lake sur-face temperature; (4) visible, NIR and microwave sensing of macrophytes; and (5)
optical sensing of trophic conditions including chlorophyll-a and euphotic depth. Sensors
used include Landsat MSS, TM and ETM+, MERIS, MODIS, SeaWiFS, AVHRR, Meteosat, TOPEX/Poseidon,
Jason-1, OSTM/Jason-2, ERS-1, ERS-2, Envisat, GFO, ICESat, ALOS-PALSAR and GRACE. The majority
of studies have been applied to the "great" lakes such as Chad, Malawi, Tanganyika and Victoria;
however, there is a growing body of literature on smaller lakes. We examine the possibilities
that remote sensing offers to monitoring and management of African lakes as well as the
potential limitations of the technology using Lake Victoria as an illustrative case. top
Barale, V.: The African Marginal and Enclosed Seas: an Overview
The African Seas include marginal basins of two major oceans, the Atlantic and the Indian,
a miniature ocean, the Mediterranean Sea, and an infant ocean, the Red Sea. The main geographical
traits of all near-coastal regions surrounding the African continent are reviewed, focusing in
particular on the surface current systems of the Atlantic and Indian Oceans, which influence
physical as well as ecological processes of local areas. These are the Canary, Guinea, Angola
and Benguela Currents, in the Atlantic African waters; the Monsoon Currents, the Somali, South
Equatorial and East African Currents, the Mozambique Current and/or Channel Eddies, the East
Madagascar Current and the Agulhas Current system, including the Agulhas Return Current and the
Agulhas Leakine, in the In-dian Ocean African waters. Further, the Mediterranean Sea and Red Sea
(and the main African Great Lakes) are also reviewed, in order to introduce their environmental
peculiarities and special challenges. While some of these basins have been sailed since ancient
times, others remain surprisingly uncharted, in particular from the scientific point of view.
Systematic and synoptic application of remote sensing techniques can provide clues to help
compose the unique mosaic of dynamical and bio-geo-chemical features of the African Seas. top
Barale, V., and M. Gade: Basic Ecosystem Dynamics in the Red Sea as seen by Sundry Remote Sensing Techniques
Abstract Patterns of algal blooming are considered to be indicators of basic eco-system dynamics
in marginal and enclosed seas. A time series of chlorophyll-like pigments concentration (chl) -
which can be interpreted as a proxy of biomass and, under certain circumstances, productivity -
derived from SeaWiFS data, from July 1999 to June 2009, was considered to explore the space-time
variability of algal blooming in the Red Sea. The comparison with concurrent surface wind speed
(ws) and direction, derived from QuikSCAT data, allowed to correlate chl variability with
atmospheric forcing. The observed chl seasonality is essentially bimodal, with a fall-winter
period of extended blooming, progressing from south to north and back, followed by a spring-summer
period of reduced blooming, at least in the northern sub-basin. This annual cycle seems to match
the climatic characteristics of the basin, the monsoon-driven wind regime in particular, and the
ensuing thermohaline circulation. The correlation with ws suggests that the Red Sea behaves like
a classical sub-tropical basin, where producion is never limited by sunlight, but always limited
by nutrient availability - a condition relaxed only in the colder season, when (wind-driven)
convection processes can enrich the euphotic zone with nutrients from deeper layers. However,
at the same time, it appears that other blooming episodes, in the southern sub-basin in particular,
are not driven directly by the wind field, but rather by other factors such as the exchange of
water with the Arabian Sea, via the Gulf of Aden and Bab-el-Mandeb. top
Bernard, S., and G. Pitcher: Ocean Colour Remote Sensing of Harmful Algal Blooms in the Benguela Syste
The Benguela, as a highly productive upwelling system, suffers from the occurrence of a
variety of harmful algal blooms, most of which are associated with elevated biomass; a
feature common to the shelf environment of upwelling systems. Most harmful blooms have in
the past been attributed to one or another dinoflagellate species, but more recently harmful
impacts have also been ascribed to other groups of phytoplankton, including diatom and
autotrophic ciliate species. Typical bloom assemblages, forcing mechanisms and harmful
impacts are outlined, and bloom types most amenable to detection with ocean colour
radiometry are identified. Inherent and apparent optical properties of these algal
assemblage types are described, and a preliminary evaluation is made of the suitability
of available ocean colour data and algorithms. The evolution of several bloom events is
described using various algorithms applied to ocean colour data from the Medium Resolution
Imaging Spectrometer (MERIS), and recommendations are made about optimal ocean colour usage
for high biomass algal blooms in coastal zones. top
Djagoua, E.V., J.M. Kouadio, C.Z. Dro, M. Bella, J.B. Kassi, B.A. Mobio, K. Affian, S. Belanger, and P. Larouche: Water constituents assessment at the Sassandra River mouth (Côte d'Ivoire): an outline based on remote sensing reflectances
Optical remote sensing of surface waters has been used to monitor the impact of the Sassandra
River - one of the four main rivers of Côte d'Ivoire - along the coast of the Gulf of Guinea.
A 5-year (2003-2007) series of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) images was chosen
to identify (spectrally) the major constituents of coastal waters under the influence of river
discharges. The percent contributions of yellow substance, i.e. coloured dissolved organic
matter (CDOM), chlorophyll-like pigments of phytoplankton (CHL) and suspended detritus (DET)
to the total reflectance (approximated by the sum of reflectances at 443, 555 and 670 nm) were
calculated. Ternary plots of these percentages pro-vided some general indications about the
relative proportions of CDOM, CHL and DET, according to the impact attributed to each water
constituent. The analysis showed that water constituents follow trends linked to the "marine"
seasons of the area. The CHL and DET contributions seem to correlate with the timing of cooler
(upwelling) periods, while CDOM seems to correlate better with that of warmer periods. The
relationship with the Sassandra river runoff is not as evident, even though CDOM increased
contributions appear to mirror the weakening of upwelling and the discharge of local rivers.
This broad ecosystem outline should be extended to the entire Côte d'Ivoire coastline, to
better classify marine waters impacted by upwelling processes or anthropogenic pollution due
to river runoff. top
Gower, J., and S. King: Satellite Water Colour Observations in African Seas
Satellite water colour image data can now be used to show the spatial patterns of coastal and
ocean water properties, especially surface chlorophyll concentration, on scales covering from
kilometers to the entire globe. The repeated coverage shows weekly, seasonal and longer term
variability, and provides a unique resource for regions where in-situ data sources are scarce,
as is the case for most waters round the continent of Africa. Easy access to extensive data
sets of satellite-measured chlorophyll, characterized through the average absorption and scattering
properties of phytoplankton, and through natural fluorescence, are now available from Goddard
Interactive Online Visualization ANd aNalysis Infrastructure (GIOVANNI), developed by the US
National Aeronautics and Space Administration (NASA), and other data systems. In addition,
data such as the MCI index from MEdium Resolution Imaging Spectrometer (MERIS),available by the
European Space Agency (ESA), derived using spectral bands near 700 nm in the near-infrared part
of the spectrum, provide further information on blooms and aquatic vegetation. We present here
results of satellite observations of various African seas, showing some of the variety of
observations and time series results possible. top
Hoepffner, N., and L. Nykjaer: Thermal Infrared Remote Sensing and Sea Surface Temperature of marine and coastal waters around Africa
Owing to satellite-derived Thermal Infrared (TIR) data, it is possible to derive large basin scale
view of Sea Surface Temperature (SST) around the African continent over the last 2 or 3 decades.
This may form the baseline against which future changes can be measured. Measurements of SST
also serve as an entry point to characterize the water dynamics along the African coast and to
under-stand where and when changes have taken place, such that possible short- to medium term
scenarios can be developed and used as management tools for precautionary measures. Significant
advances in TIR technology have been achieved to build the necessary confidence in satellite-based
SST measurements for research, as well as for operational and commercial purposes. An effective
dissemination of these EO value added products to African institutions and policy-makers is a
key condition for long-term sustainability of coastal and marine resources. The chapter presents
a variety of applications using TIR images and SST data that have contributed to develop the
necessary knowledge and competences that are critical for the implementation of conservation
and management strategies at continental, regional and national scales. top
Johannessen, J.A., et al.: Use of SAR data to monitor the greater Agulhas Current System
The strong and dynamic greater Agulhas Current is known to have significant influence on the
local marine environment and ecosystem. It is also considered to play an important role in the
global thermohaline circulation, notably due to the transport of heat and salt from the Indian
Ocean into the South Atlantic Ocean. Regular monitoring of the dominant processes and variability
within the greater Agulhas Current is thus highly needed. Recently Doppler-derived ocean surface
velocities from the European Space Agency´s (ESA) Envisat Advanced Synthetic Aperture Radar (ASAR)
have demonstrated abilities to manifest the intensity of surface currents. In this paper the
regular direct surface velocity estimates of the greater Agulhas Current from the ASAR since
summer of 2007 are presented. These estimates are assessed by direct comparison to other
independent estimation of the surface current in the greater Agulhas current obtained from
surface drifter data, radar altimetry and an ocean circulation model. The results are promising
and highlight that the Doppler-based ocean surface velocity retrieval offers a new innovative
approach to monitor and advance the understanding of the dynamic processes of the greater
Agulhas Current. top
Karimova, S.S:, and M. Gade: Eddies in the Red Sea as seen by Satellite SAR Imagery
We present the results of our observations of mesoscale and sub-mesoscale eddies in the Red Sea
based on Synthetic Aperture Radar (SAR) imagery. The dataset used includes about 500 Envisat
Advanced SAR (ASAR) images obtained in 2006-2011 over the Red Sea. We found more than 1000
sub-mesoscale eddies, which manifest in the SAR imagery both due to surfactant films ("black"
eddies) and wave/current interactions ("white" eddies), depending on the local wind speed.
Sub-mesoscale eddies in the Red Sea seem to be more innumerous than in other inner seas,
presumably due to a relatively deep upper mixed layer in this basin. Moreover, more than
50 meso- and basin-scale eddies were found, whose rotation was mostly anti-cyclonic and whose
diameters ranged up to approx. 200 km. Most of the basin-scale eddies were found between
21°N and 24°N, which is in agreement with earlier observations and with numerical modeling. top
Kostianoy, A., O.Yu. Lavrova, and D. Solovyov: Oil pollution in coastal waters of Nigeria
The petroleum industry in Nigeria has become the largest industry and the main Gross Domestic
Product (GDP) generator in Western Africa. Nigeria's proven oil reserves make Nigeria the most
affluent country in Africa and the tenth most petroleum-rich one in the world. The main oil
fields are concentrated in and around the Niger River Delta, which is seriously damaged by
oil leakages. It has been estimated that between 9 and 13 million barrels have been spilled
since oil drilling started in 1958. Between 1976 and 2001 the Government documented 6817 spills,
but analysts suspect that the real number may be ten times higher. Lit-tle is known about oil
spills in the coastal zone of Nigeria, but offshore spills con-taminate coastal environments
and cause a decline in local fishing production. We present a general view on oil pollution
in the coastal waters of Nigeria, based on the analysis of historical information and recent
Advanced Synthetic Aperture Radar (ASAR) data, with a focus on the Bonga oil spill case study,
which occurred on 20 December 2011. top
Krug, M., P. Cipollini, and F. Dufois: Observing the Agulhas Current with Sea Surface Temperature and Altimetry Data: Challenges and Perspectives
The Agulhas Current is a challenging region for satellite remote sensing observations. Strong
evaporation rates above the current core and the Retro-flection reduce the number of cloud-free
observations from Infra-Red sensors, while microwave radiometers and altimeters measurements
suffer from the prox-imity of the current to the coast in the northern region. Infra-Red
observations of the Agulhas Current significantly improved with the launch of the Meteosat
Second Generation satellite, but Infra-Red Sea Surface Temperature datasets still suffer from
inadequate cloud masking algorithms, particularly in regions of strong temperature gradient.
Despite both Sea Surface Height and Sea Surface Tempera-ture observations being severely
compromised in the northern Agulhas current, a synergetic use of merged altimetry and high
frequency Infra-Red Sea Surface Temperature imagery provides a means to track deep-sea eddies,
document their influence on the Agulhas Current and helps us improve our understanding of the
Agulhas Current variability. top
Lehner, S., et al.: Ship surveillance with High Resolution TerraSAR-X Satellite in African Waters
Ship detection is an important application of monitoring of environment and security or safety
issues in African Waters. In order to overcome the limitations by other monitoring systems,
e.g. coastal radar, surveillance with satellite Synthetic Aperture Radar (SAR) is used because
of its potential to detect ships at high resolution over wide swaths and in all weather
conditions and independent from sun illumination. TerraSAR-X (TS-X) is an X-band polarimetric
SAR capable of imaging up to 1m resolution in Spotlight mode. TS-X can be used for a wide
variety of applications and methods of analysis including visual interpretation, mapping,
digital-elevation-model creation, disaster monitoring, and oceanog-raphy. Results on the
combined use of TS-X ship detection, Automatic Identifica-tion System (AIS), and satellite
AIS (SatAIS) are presented. Using AIS is an effective terrestrial method for tracking vessels
in real time typically up to 40 km off the coast. SatAIS is a space-based system with nearly
global coverage for monitoring of AIS equipped ships. Since not all ships operate their AIS
and small-er ships are not equipped with AIS, space borne SARs provide complimentary means
for ship monitoring. As cases, images were acquired over the Somali Coast Area, South African
Coast and Gibraltar in Stripmap mode with a resolution of 3m at a coverage of 30km×50km.
The rapid tasking performance as well as the short response time of the TS-X data acquisition
of the ground segment DLR-BN (Ground Station Neustrelitz, Germany), are very helpful to monitor
hotspot areas such as the Gulf of Aden. For ascending orbits the delivery time of ship detection
products is less than 20 min. Along with the detected ship positions, estimated wave heights
and wind fields derived from large-area TS-X imagery can be used to get a detailed maritime
picture of the situation. top
Magelhaes, J., and J. da Silva: Internal Solitary Waves system in the Mozambique Channel
Satellite images of the Mozambique Channel (MC), collected by Synthetic Aperture Radars (SARs)
from the Envisat and European Remote Sensing (ERS) satellites, reveal sea surface signatures of
oceanic Internal Solitary Waves (ISWs). The MC has been expected to be a major hotspot for the
generation of Internal Tides (ITs) in the ocean. New results now show that the Sofala bank (or
shelf, located near 20°S, 36°E) is indeed a strong and previously unknown source for the generation
of ITs and ISWs. The hotspot region is located between 20 and 21°S, where the barotropic tidal
forcing and tidal transports are highest in the area, due to the particular nature of the bathymetry
there. Two distinct types of ISWs are observed to travel offshore, away from the shelf-break,
and their possible generation mechanisms are discussed. Mode 2 ISWs propagating in MC are also
observed in SAR imagery. It is discussed that they may be generated by a tidal beam impinging the
thermocline from below, in a similar process to some of the Mode 1 ISWs generated off the Sofala
bank. ISW refraction patterns, often observed in SAR imagery in MC are presented, and a particular
example is shown where ISWs and eddy-like features are seen to interact. The influence of these
rotating features in the refraction patterns is briefly discussed. Finally, it is shown that
large-scale atmospheric gravity waves of solitary-like form are also frequently observed in the
region, and thus care must be taken when discriminating oceanic and atmospheric ISW signatures
in SAR images, if a correct interpretation is to be made. top
Ohde, T., and H. Siegel: Impacts of Saharan dust on the marine environment in the area off Northwest Africa
The main sources of nutrient supply in the area off Northwest Africa are upwelling and Saharan dust
deposition. Their influence on phytoplankton de-velopment was evaluated by different methods.
Statistical analyses showed that alongshore wind stress and induced upwelling were most significantly
responsible for surface Chl-a variability mainly in winter and spring with delay of up to 16 days.
Only 5 % of the Chl-a variability was related to the dust input. All strong Saharan dust storms
between 2000 and 2008 were identified by remote sensed dust aerosol optical depth. Only some of
the events caused a biological response expressed by an increase of surface chlorophyll-a. Time
lags between dust deposi-tion and enhancement of chlorophyll-a between 8 and 16 days were determined.
The chlorophyll-a concentration was increased up to 2.4 mg m-3. Atmospheric dust modifies the
amount and spectral distribution of the water light field. In the applied optical model the dust
effect on incident solar radiation was parameterized by radiation measurements. The photosynthetically
active radiation was reduced up to 19.3 % in the upper water column. The impacts of spectral effects
on photosynthetically active radiation were different in oceanic and coastal regions. A compensation
of the spectral effects at water depths of about 7 m was only observed in ocean regions because
of different light attenuation in coastal areas. Saharan dust also impacts satellite derived ocean
surface wind speeds. The influence depended mainly on the strength of dust storms, the microwave
frequency and the wind speed. The impact was higher for stronger dust storms, higher frequencies
and lower wind speeds. top
Siegel, H., T. Ohde, and M. Gerth: The upwelling area off Namibia, the northern part of the Benguela current system
In the area off Namibia satellite remote sensing data of the visible and infrared spectral range
were used to investigate the upwelling processes and the biological response. Satellite derived
Sea Surface Temperature was applied to study upwelling processes in relation to the driving trade
winds. The investigations were focussed on the intensity and horizontal extent, the temporal and
spatial variability including inter-annual and climate scales. Ocean colour satellite data allow
investigation of the response of surface water to the nutrient input into the euphotic zone by
upwelling processes. Observations in the area revealed, that the phytoplankton development starts
with species absorbing light in the visible spec-tral range (diatoms and dinoflagellates) and may
end in persistent shallow surface filaments with light scattering algae blooms. These blooms of
coccolithophores identified by different in situ methods changed the water colour by strong
particle scattering to milky turquoise discolorations. Further milky turquoise discolorations
were identified as sulphur plumes. Low wind periods support the degradation of organic matter
and the development of hydrogen sulphide in the bottom layer. After the onset of the trade winds
and the offshore transport of surface water hy-drogen sulphide enriched waters reaches with the
near-bottom counter current the coast. Upwelling transports the water to the surface where the
hydrogen sulphide will be oxidised to elemental sulphur. An algorithm was developed to identify
and separate the sulphur plumes from algae blooms and other features on the basis of highly
spectrally resolved satellite data from the MERIS sensor. The algorithm identified only coastal
plumes as sulphur and that offshore plumes are formed by coccolithophores. The sulphur season is
the boreal spring starting in February and reaching the maximum in April. top
Weil, L.G., A.G. Ramos, J. Coca, and A. Redondo: Mesoscale Dynamics in the Canary Islands Area as Observed Through Complementary Remote Sensing Techniques
The combined use of data collected by multi-spectral radiometers, operating in the visible and
infrared spectrum, and altimeter radars, operating in the microwave spectrum, allowed the detailed
assessment of oceanic mesoscale dy-namics in the Canary Islands area. Island-induced eddies are
recurrent oceano-graphic structures of the region and contribute, together with other features
originating from the African near-coastal zone, like upwelling filaments, to the variability of
the physical and biological field of the Canarian Archipelago. The analysis of satellite-measured
parameters with complementary specificities - namely brightness temperature and sea surface
temperature, chlorophyll-a, as well as sea level anomaly - provided a description of the mesoscale
variability around the Islands, covering in detail an entire seasonal cycle in the period 1998-1999.
An overview is given of the spatial and temporal characteristics of all mesoscale features observed
in the satellite imagery, including their origin, evolution and interaction with each other and
their environmental surroundings. top
People Involved
This list is not complete, since it does not contain all co-authors. The complete List of Contributors
will be included in the book.
One of the contributors, Ernst Maier-Reimer, passed away recently, on 22 July 2013, just before the editorial efforts were finished.
Ernst supported us as a reviewer and we are grateful to him for his valuable contribution to this book. MG & VB
Acker, James G.,
NASA GES DISC Code 610.2, Greenbelt, MD, USA Ahmed, Mahmoud H.,
National Authority for Remote Sensing and Space Sciences (NARSS), Cairo, Egypt Alpers, Werner,
Institut für Meereskunde, Universität Hamburg, Hamburg, Germany Armstrong, Roy A.,
Bio-Optical Oceanography Laboratory, Department of Marine Sciences, University of Puerto Rico, Mayaguez, Puerto Rico Arnone, Robert,
US Naval Research Lab, Bio-Optical/Physical Processes and Remote Sensing Section, Stennis Space Center, MS, USA Ballatore, Thomas J.,
Lake Basin Action Network, Moriyama, Japan Banzon, Viva,
NOAA, USA Barale, Vittorio,
Institute for Environment and Sustainability, Joint Research Centre of the EC, Ispra (VA), Italy Beggs, Helen,
Bureau of Meteorology, Australia Brandt, Peter,
IfM-Geomar, Kiel, Germany Brockmann, Carsten,
Brockmann Consult, Geesthacht, Germany Brusch, Stephan,
Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, 82234 Wessling, Germany Burchard, Hans,
Baltic Sea Research Institute, Rostock-Warnemünde, Germany Byfield, Valborg,
National Oceanography Center, Southampton, UK Cipollini, Paolo,
Laboratory for Satellite Oceanography, National Oceanography Centre, Southampton,
United Kingdom Donlon, Craig,
ESA, Frascati, Italy Dupouy, Cecile,
Institut de Recherche pour le développement, Marseille, France Ermakov, Stanislav A.,
Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia Evans, Robert,
University of Miami, Miami, FL, USA Foster, Ralph,
Applied Physics Laboratory, Seattle, WA, USA Gade, Martin,
Institut für Meereskunde, Universität Hamburg, Hamburg, Germany Garcia-Gorriz, Elisa,
Institute for Environment and Sustainability, Joint Research Centre of the EC, Ispra (VA), Italy Gerth, Monika,
Baltic Sea Research Institute, Rostock-Warnemünde, Germany Gower, Jim,
Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, BC, V8L 4B2, Canada Greidanus, Harm,
Institute for the Protection and Security of the Citizen, Joint Research Centre of the EC, Ispra (VA), Italy Holt, Benjamin M.,
Jet Propulsion Laboratory, NASA, Pasadena, CA, USA Horstmann, Jochen,
Institute for Coastal Research, Helmholtz Zentrum Geesthacht, Geesthacht, Germany Ivanov, Andrey,
P.P. Shirshov Institute of Oceanology, Moscow, Russia Johannessen, Johnny A.,
Nansen Environmental and Remote Sensing Center, Bergen, Norway Kahru, Mati,
University of California, San Diego, California, USA Karimova, Svetlana S.,
Space Research Institute, Russian Academy of Sciences, Moscow, Russia now at: Institute for Coastal Research, Helmholtz Zentrum Geesthacht, Geesthacht, Germany King, Stephanie,
Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, BC, V8L 4B2, Canada Kopolevich, Oleg,
P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences,Moscow, Russia Kostianoy, Andrey G.,
P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences,Moscow, Russia Kretzel, Adam,
University of Gdansk, Gdansk, Poland Krug, Marjolaine,
Ecosystem Earth Observations, Council for Scientific and Industrial Re-search, Cape Town, South Africa Kudryavtsev, Vladimir,
NIERSC, St. Petersburg, Russia Lavrova, Olga Yu.,
Space Research Institute, Russian Academy of Sciences, Moscow, Russia Lehner, Susanne,
Deutsches Zentrum für Luft- und Raumfahrt, Bremen, Germany Magelhaes, Jorge M.,
CIIMAR, Universidade do Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal Maier-Reimer, Ernst †,
Max-Planck-Institute of Meteorology, Hamburg, Germany Marullo, Salvatore,
Centro Ricerche Casaccia, ENEA, Casaccia, Italy Matthews, Mark,
University of Cape Town, Cape Town, South Africa Mauri, Elena,
Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Trieste, Italy Melack, John,
University of California, Santa Barbara, CA, USA Melsheimer, Christian,
University of Bremen, Bremen, Germany Minett, Peter,
University of Miami, Miami, FL, USA Mitnik, Leonid,
Pacific Oceanology Institute, Far-Eastern Branch, Vladivostok, Russia Monaldo, Frank,
Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA Morovic, Mira,
Institute of Oceanography and Fisheries Croatia, Split, Kroatia Ohde, Thomas,
Baltic Sea Research Institute, Rostock-Warnemünde, Germany Pleskachevsky, Andrey,
Deutsches Zentrum für Luft- und Raumfahrt, Bremen, Germany Pozdnyakov, Dmitry,
NIERSC, St. Petersburg, Russia Quadfasel, Detlef,
Institut für Meereskunde, Universität Hamburg, Hamburg, Germany Romeiser, Roland,
University of Miami, Miami, FL, USA Siegel, Herbert,
Baltic Sea Research Institute, Rostock-Warnemünde, Germany da Silva, Jose C.B.,
CIIMAR, Universidade do Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal Smyth, Timothy J.,
Plymouth Marine Laboratory, Plymouth, UK Solovyov, Dmytro M.,
Marine Hydrophysical Institute, National Academy of Sciences of Ukraine, Sevastopol, Ukraine Stanichny, Sergey,
Marine Hydrophysical Institute, National Academy of Sciences of Ukraine, Sevastopol, Ukraine Stips, Adolf,
Institute for Environment and Sustainability, Joint Research Centre of the EC, Ispra (VA), Italy Topouzelis, Konstantinos,
Department of Marine Sciences, University of the Aegean, Mitilene, Greece Trees, Chuck,
NATO Undersea Research Center, La Specia, Italy Weil, Luis Garcia,
Departamento de Física, Universidad de Las Palmas de Gran Canaria (ULPGC), Las Palmas, Spain
Page maintained by Martin Gade - last update: 31 December 2013