Vittorio Barale

MERIS potential for ocean colour studies in the open ocean

The interest of space observations of ocean colour for determining variations in phytoplankton distribution and for deriving primary production (via models) has been largely demonstrated by the Coastal Zone Color Scanner (CZCS) which operated from 1978 to 1986. The capabilities of this pioneer sensor, however, were limited both in spectral resolution and radiometric accuracy. The next generation of ocean colour sensors will benefit from major improvements. The Medium Resolution Imaging Spectrometer (MERIS), planned by the European Space Agency (ESA) for the Envisat platform, has been designed to measure radiances in 15 visible and infrared channels. Three infrared channels will allow aerosol characterization, and therefore accurate atmospheric corrections, to be performed for each pixel. For the retrieval of marine parameters, nine channels between 410 and 705nm will be available (as opposed to only four with the CZCS). In coastal waters this should, in principle, allow a separate quantification of differ...

Multisensor monitoring of plume dynamics in the northwestern Mediterranean Sea

We used data from various space-borne sensors to monitor the marine ecosystem in the northwestern Mediterranean Sea, at the Costa Dorada, between the City of Barcelona and the estuary of the river Ebro. The aim of this study was to demonstrate that the combination of different remote sensing data (acquired at different electromagnetic frequencies) allows for an improved monitoring system, in particular for a better monitoring of the marine ecosystem and, hence, a better coastal zone management. We present remote sensing data acquired by the Synthetic Aperture Radar (SAR) and the Along-Track Scanning Radiometer (ATSR) aboard the Second European Remote Sensing Satellite (ERS-2), and by the Sea-viewing Wide Field-of-view Sensor (Sea WiFS) on the SeaStar satellite. By combining the different data we are able to overcome specific drawbacks of the single sensors, like an insufficient temporal coverage, or a strong dependence on weather and daylight conditions.Within the study area two main features have been selected as examples, which are well visible on many of the analysed images. The first one exhibits a higher load of chlorophyll-a and surface-active compounds and a lower sea surface temperature (SST), which is likely to be caused by the plume of the river Llobregat, southwest of Barcelona. It can clearly be seen from the imagery how the river plume is driven along the coast by the local currents. The second feature can be related to cooling water being released from a nuclear power plant and causing turbulence in the water body, which in turn gives rise to signatures visible on the ERS-SAR imagery.

Marine remote sensing information system (MARSIS): a conceptual design

Abstract Remote observations of the sea produce large quantities of data, which must pass through several levels of processing, requiring special facilities and expertise, before reaching the end user. As a consequence, most marine remote-sensing data available at this time are not fully used because the average potential user does not have the means or competence to do so. These information-management problems could be eased through the development of a Marine Remote-Sensing Information System (MARSIS), capable of delivering value-added data sets both according to standard statistical and dynamical procedures and according to specific user requests. A regional MARSIS Centre is envisioned as the nodal point of a distributed information system, which includes three basic modules, devoted respectively to processing, management and communication, as well as a dedicated knowledge-based system connecting the modules themselves to original data repositories and final users. The MARSIS concept has been designed ...

Basic Ecosystem Dynamics in the Red Sea as Seen by Sundry Remote Sensing Techniques

Patterns of algal blooming are considered to be indicators of basic ecosystem dynamics in marginal and enclosed seas. A time series of chlorophyll-like pigment 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 production 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.

European Atlas of the Seas: “a picture is worth a thousand words”

The European Atlas of the Seas offers a snapshot of environmental and socio-economic features that characterize the coastal and marine environment. The latest release (Version 4) addresses the public in general, but also non-specialist experts involved with environmental issues, human activities or policies related to Europe’s coasts and seas. The information content of the Atlas comprises a series of geographical layers, subdivided in “background maps”, “thematic maps” (i.e. maritime Europe, natural setting, sea bottom, sea level rise, security, transport, tourism, energy, wind, fisheries and fish consumption) and “do-it-yourself maps” (dealing with marine knowledge, nature and environment, socio-economics, fisheries, aquaculture, transport, energy, sea bed mining, coastal tourism, Maritime Spatial Planning, integrated maritime surveillance, and international ocean governance). All maps follow consistent cartographic rules and can be extracted for external use. The Atlas database is updated regularly, but historical data remain accessible after the updates, so that time series may be constructed. Tools for map exploration and combination can be used to combine together more layers, providing professional users with analysis and interpretation capabilities, to couple data into graphical indicators. The Atlas aims to supports also policy making, on marine environment, maritime issues and economic sectors, both within and outside the European Institutions (e.g. on Common Fisheries Policy or Maritime Spatial Planning). Further, it expands the same support to near-coastal issues and matters related to land-sea interactions. The web application for accessing Atlas contents offers links to other Marine Information Systems, and is available to a broad audience from computers, tablets and mobile devices.

Clean seas: a North Sea test site

The Clean Seas project focused on the role that existing Earth observing satellites might play in monitoring marine pollution. Results are presented here from August 1997, for the North Sea test site, using sea surface temperature (SST), colour and synthetic aperture radar (SAR) images in conjunction with a hydrodynamic model. There was good correlation between data sources, e.g. between SST and ERS-2 SAR images. Both datasets showed the development of fine plume structures close to the Rhine outflow, apparently associated with the outflow, and possibly caused by tidal pulsing of the Rhine Plume. The model reproduced general temperature and sediment distributions well, but fine structures were not reproduced. Model sediment distribution patterns were verified using ‘chlorophyll concentration’ data from colour sensors, representative of sediment concentration in turbid water. In conjunction with the visible channels of the Advanced Very High Resolution Radiometer and Along-Track Scanning Radiometer, they give an uncalibrated measure of the sediment load. The model gives a more complete picture of the temporal dispersion of the Rhine Plume over time than is evident from the remotely sensed data alone.

Erratum to: Multisensor monitoring of plume dynamics in the Northwestern Mediterranean Sea

Gade, M.; Barale, V. & Snaith, H.M. 2003. Multisensor monitoring of plume dynamics in the northwestern Mediterranean Sea. J. Coastal Conserv. 9: 91–96.Due to a miscommunication the figures below (pp. 93, 94, and 95) were erroneously printed in black and white. Here are the correct versions in colour.