Preliminary Activity for identification and characterization of an international CAL/VAL site
Musacchio M., F. Doumaz, M. Favalli, A. Nedjari, S. Maouche, M. Rahil (2015). Preliminary Activity for identification and characterization of an international CAL/VAL site, Rapporti tecnici INGV, n.329.
During the four years Italian Space Agency (ASI) funded project “ASI-AGI” (Analisi Sistemi Iperspettrali per le Applicazioni Geofisiche Integrate) INGV has developed specific algorithms and products for various geophysical applications to be applied on hyperspectral data that will be acquired during lifetime of the next ASI-PRISMA (Precursore IperSpettrale della Missione Applicativa). PRISMA is a pre-operative small Italian hyperspectral mission aiming to observe routinely and to characterize the earth surface by coupling an hyperspectral and a panchromatic sensor. In this context ASI-AGI project contributes to develop applications and provides products to institutional and scientific users for environmental observation and risk management.
Moreover the identification of a CAL/VAL site is a direct interest of European Space Agency (ESA) in the framework of the Committee on Earth Observation Satellite (CEOS) actions. The scope of this project is to select, identify and characterise test sites, to be used as a reference, for the calibration and characterisation of different sensor types and identifying and characterizing test sites that can be used for external calibration. The project is part of the ESA strategy for ensuring the quality (in terms of calibration, validation and operational quality) of data developed for current and future missions within the Explorers and he European Earth observation programme Copernicus, previously known as GMES (Global Monitoring Environment and Security) framework. The choice of a sites or the use of a site depends on the nature of the space mission (ocean color, terrestrial biosphere), by the sensor resolution (high medium or low spatial resolution), and then on the needs to produce reliable information in terms of accuracy and stability. In this context from May 6th and 11th, 2014 INGV has performed a pre-survey for the identification and characterization of a vicarious calibration-validation remote site supporting the future ASI space missions. This field campaign has been conducted in Algeria in the Western Sahara region, in the Bechar province, more precisely in the area ranging from Ougarta and Beni Abbes. While the CAL/VAL activities of ASIAGI project have been already described in Colini et al.,  this report describes the activity done during the dedicated field campaign aimed to identify a new vicarious test site in North Africa in the Algerian desert. In the follows, we present the region Ougarta, its location, the overall field campaign organization, geology and sites description that have been measured in the framework of this project.
All these information are required in order to verify the compliance of the chosen site with the retained criteria expressed in Berthelot and Santer . The level of compliance will allow the characterization of inland calibration-validation site as:
LES: Land Equipped Site
LNES: Land Non Equipped Site
Equipped sites correspond to a test sites and are adapted for Optical sensor medium resolution and geostationary instruments. They can be used for Optical sensor high-resolution sensors as well. Because of high radiometric requirements, class 2 sensors can be used as reference for cross calibration with class 3.