Kalicotier: a Demonstration Data Server Toward Dedicated Earth Observation Services in the Coastal Zone
Lerebourg, Christophe1; Selle, Arnaud2; Mazeran, Constant1; Henry, Patrice2; Bruniquel, Véronique1; Deboissezon, Hélène2
1ACRI-ST, FRANCE; 2CNES, FRANCE
Around 44% of the world's population lives within 150km of the coast. Therefore, an important part of economic activities take place in the coastal zone: marine related activities (fisheries, fish farming, shipping, mining, leisure...) as well as terrestrial activities concentrated around urban centres. Being at the interface between land and ocean, the coastal zones are under the influence of a complex mixture of natural and anthropogenic phenomena originating from both oceans and lands. For the latest, river discharge which carries pollution originating from agricultural, industrial and domestic activities of the entire river basin is a major contributor on coastal environment. As a consequence, the coastal zone is the major place of interest for environmental and safety monitoring. This complexity leads to an important need of integrated coastal management in which remote sensing can play an important part from long term monitoring to fast analysis and response to natural or industrial hazards.
In order to address these needs, the Kalicotier demonstration data server has been funded by CNES as part of the GIS COOC data portal (French Scientific group in Ocean colour). This portal, dedicated to coastal satellite data and available at http://kalicotier.gis-cooc.org is an ocean colour data server providing extensive remote-sensing datasets for the study of coastal regions of major oceanographic interest. Kalicotier so far provides an easy and fast access to MERIS Full Resolution data (300m) on five coastal sites: Ligurian Sea, English Channel, Bay of Biscay, New Caledonia and Vanuatu Islands and the South Vietnam region. Each site is managed in partnership with a researcher of the scientific community locally involved in the region, who insures relevance and update of the information. The objective of Kalicotier is to demonstrate on a limited number of coastal sites the utility of providing comprehensive satellite time series. If relevant, data from other sensors will be added to the data portal. This could include other ocean colour sensors (SeaWiFS, MODIS, VIIRS, OLCI) as well as other data type (SST, SSH, wind speed, broad band high resolution radiometric sensors). Ultimately, the concept would be extended and integrated in operational services with a focus on NRT and RT data dissemination.
The specificity of the coastal zone regarding atmospheric correction has put forward the need to provide to users an improved algorithm: SAABIO (Semi Analytical Atmospheric and BIO-optical processor), described hereafter. Together with the satellite data, Kalicotier provides validation plots for each selected area thanks to long term in situ acquisition systems (notably BOUSSOLE, AERONET-OC and SOMLIT) and oceanographic cruises provided by institutional partners. Main features of Kalicotier portal are (figure 1):
Access to full time series of MERIS FR Level 1 and Level2 products (NetCDF format) over five coastal regions;
Access to two processing versions (MERIS 3rd reprocessing and an experimental processor, SAABIO, described hereafter);
Extraction capability of single Level 2 products from NetCDF files to reduce storage volume in users facilities;
Fast and easy visualization of all MERIS products;
Visualization tool to select none cloudy images;
Validation plots of satellite data against in situ measurements;
Data are restricted to research and educational use;
Figure 1: Kalicotier web page, http://kalicotier.gis-cooc.org
SAABIO is an experimental processor developed by CNES and ACRI-ST, alternative to the Case 2 neural network of the MERIS 3rd reprocessing (Figure 2). It is based on:
An alternative Bright Pixel Atmospheric Correction, using a semi-analytical approach to retrieve residual marine reflectance in the red and near-infrared;
The GSM, semi-analytical bio-optical model to retrieve Chl, bbp and cdm;
Figure2: Normalized reflectance at 490nm of AAOT (AERONET-OC). MERIS 3rd reprocessing (left) and SAABIO (right).
Kalicotier is foreseen to evolve in the near future and users are invited to express their needs for evolution, providing other alternative algorithms, requiring for other EO data as well as suggesting evolution of the data portal itself. The purpose of the presentation is the description of the SAABIO algorithms and the main outcomes of the reprocessing as well as the usages carried out from the Kalicotier datasets.
