National Institute for Marine Research and Development (NIMRD) Grigore Antipa, Constanta, Romania

Maritime Hydrographic Directorate (MHD), Constanta, Romania

Research Center of the Navy, Costanta, Romania)

Institute of Oceanology, Bulgarian Academy of Sciences (IO-BAS), Bulgaria, Varna

Joint Research Centre of EC (JRC), Ispra, Italy (through a Letter of Endorsement )

Funding Agencies

European Space Agency (ESA) within the framework of the MERIS Validation activities.

Romanian Space Agency (ROSA) within the framework of the PECS activities.

Rationale and Justification

The Black Sea receives drainage from almost one-third of the continental Europe (five times its own surface) which includes significant portions of 17 countries, 13 capital cities and some 160 million people. Of all the basins of the world ocean, the environmental degradation in the Black Sea is the most severe.

The monitoring of trophic and geochemical status of the Black Sea can rely on satellite ocean color data. In fact such a technology allows for the determination at synoptic scale of water quality indicators like: chlorophyll a concentration (and potentially accessory pigments) used as a proxy for phytoplankton biomass; concentration of total suspended matter and colored dissolved organic matter through its absorption properties.

Current limitation in the operational use of satellite ocean color data in the Black Sea and in other marginal seas is the lack of regional bio-optical algorithms linking the satellite signal to the specific water quality indicators. In fact operational satellite products generally rely on algorithms developed for global applications which generally are the source of large uncertainties in coastal areas. This urges the development of specific regional bio-optical algorithms on the basis of comprehensive data sets of statistically representative in situ measurements.

Additional need is the capability of checking and hopefully monitoring on a continuous basis, the performance of the atmospheric correction process (i.e., minimization of atmospheric effects in satellite ocean color imagery) over turbid waters, where currently applied methods might lead to poor results.

Current Status and Objectives

Optical remote sensing (satellite ocean color) has demonstrated the capability to provide synoptic information of the optical and biogeochemical properties of the oceans. This is based on the determination of the spectrum of the water leaving radiance (i.e., the radiance emerging from below the sea surface obtained from the top-of-atmosphere signal corrected for the atmospheric perturbation). The amplitude and spectral shape of this primary geophysical ocean color product (generally given as remote sensing reflectance), is then interpreted in terms of derived products such as concentrations of optically significant constituents or inherent optical properties for bio-geo-chemical and environmental applications at global or regional scales. Specifically, satellite ocean color has given another dimension to marine biogeochemistry and ecosystem studies, providing key information for instance on the timing and spatial distribution of plankton blooms, and the magnitude of primary production. In line with these achievements, satellite ocean color produced synoptic views of patterns of seawater optically significant constituents in the Black Sea. However, these products exhibit large uncertainties in coastal regions. This is mostly due to the use of techniques suitable for global applications which may not account for specific ecological regimes

The proposed project, within the framework of ESA and ROSA coordinated activities, and with the collaboration of JRC, aims at carrying out dedicated bio-optical cruises in the Romanian waters influenced by the Danube discharges. The data collection carried out by the partnership will basically rely on the equipment and methodologies regularly applied by the JRC for mapping the bio-optical properties of the European seas and complying with the MERIS Validation Team protocols. The in situ data collected during these cruises will then be applied: i. to verify the consistency of the models utilized for the atmospheric correction process in sediment dominated waters with specific reference to the MERIS bright pixel atmospheric correction; ii. to support the development of regional bio-optical algorithms and models for the determination of optically significant seawater constituents in the form of concentration or inherent optical properties from satellite ocean color sensor data (with the highest priority for MERIS imagery).

The project also aims at operating an autonomous above-water radiometer on an oil platform in front of the Romanian coast. This system will produce data which will be used for the continuous assessment of the atmospheric correction process of current satellite ocean colors sensors (with the highest priority for MERIS). The autonomous radiometer will be provided by the JRC and will be part of the international AERONET-OC network. The long-term operation of the system will be taken over by NIMRD “Grigore Antipa” with the support of the JRC. The system will ensure real - time transmission of data. These will be available to the project partnership without restrictions from the AERONET - OC data base and also from the ESA MERMAID server. The operation of the above-water system will be complemented by an ADCP (Acoustic Doppler Current Profile) operated near the deployment platform to monitor sea currents and wave regimes. The data exploitation will comprise the continuous analysis of in-situ and satellite match-up data, and an evaluation of the sea current effects on them.

The development and execution of this project will befit from complementary activities carried out in the Black Sea within the framework of the project Bio-Optical Characterization of the Black Sea for Remote Sensing Applications (NATO Science for Peace Project # 982678). The project will also benefit from the NIMRD data archive of transparency and sea color produced during different oceanographic cruises from 1971 to 2009.

Data

The in situ data collected within the framework of the oceanographic cruises will comprise state-of-the-art and quality assured comprehensive measurements of apparent and inherent optical properties of seawater, in addition to the concentration of optically significant constituents (see Table 1). Apparent optical properties are the remote sensing reflectance and the diffuse attenuation coefficient (all determined through in-water radiometric profiling). Inherent optical properties are the absorption, scattering and back-scattering coefficients (determined through in-water profiling). Concentrations of specific seawater suspended constituents include those of pigments and total suspended matter (determined from laboratory analysis of water samples).

The in situ data collected with the autonomous above-water radiometer on a continuous basis will be the remote sensing reflectance and the aerosol optical thickness (see Table 2).

Table 1: Bio-optical quantities and concentration of seawater constituents going to be determined during the field activities.

Table 2. Data products from the autonomous above-water system deployed on an oil platform.

Milestones and Deliverables

Milestones of the project are: i. the installation of the autonomous system on an offshore oil platform in the Danube area during the first year; ii. the completion of the oceanographic campaigns scheduled for the first and second year; and iii. yearly summary of data analysis. Accordingly deliverables are:

1. Data from the fixed platform (i.e., the radiometric data accessible from the AERONET-OC and MERMAID servers and ADCP data accessible from NIMRD);

2. Data from ship campaigns (radiometric data and inherent optical properties);

3. Annual scientific reports and publications documenting the field activities and results from data analysis. It is expected that results are also presented in at least one workshop (e.g., MERIS Validation Team Meeting) or conference per year.

Budget for NIMRD “Grigore Antipa” from ESA and ROSA:

ESA funding through MERIS Validation activities

(1) Funding whose availability needs to be confirmed

ROSA funding through PECS activities

Travel funding will allow for the participation to workshops and conferences, and additionally will support the participation to training activities (e.g., ESA, JRC, IOCCG trainings on satellite ocean color).