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This web site is intended to be useful to all the people involved in the campaign activities carried out in Barrax, La Mancha, Spain, from 12 to 14 of July 2003. Initially, this activities were related with several projects not connected among them, but finally, they have become a joint activity under the umbrella of a formal ESA (European Space Agency) campaign as part of Phase-A Preparations for the SPECTRA mission.

The reason for the selection of the 12-13-14 of July were the coincidence with three consecutive days of CHRIS/PROBA overpasses. Since most of the other planned activities were somehow flexible in dates (more continuous satellite overpasses) the particular orbit of PROBA was the driver in choosing the preferable dates for the campaign.

For those not familiar with PROBA, the satellite was launched in a kind of orbit that has some special features. It makes possible to have coverage over a given site for 2 or 3 consecutive days, and then several days (around 6 at the latitude of Barrax) in between where access to the site is not possible due to the orbital coverage. The situation over Barrax on 12-13-14 July was particularly favourable, because PROBA almost passed over (-4 across-track zenith angle) on 13 July, and then on 12 July (+20 across-track zenith angle) and on 13 July (-27 across-track zenith angle) we had additional multi-angular coverage. Each orbit provides 5 images with different view angles (-55, -36, 0, +36, +55 along-track zenith angles). Then, it seems these were the more optimum dates for the campaign for angular coverage. Overpass times were 11:07, 11:19 and 11:32 for the three days, 12-13-14 July respectively:

Note that 3 multiangular CHRIS/PROBA datasets have been already acquired over Barrax in the previous weeks to the campaign, and the quality of the data is excellent (both geometrically and radiometrically). The plan was to get a multiangular reference dataset with 15 angles (5 angles along each of the 3 different orbits) and 62 spectral channels per angle during this concentrated campaign. This intensive dataset plus the multitemporal series of CHRIS data being collected over Barrax from April to October 2003 will represent the SPECTRA reference dataset for SPECTRA-related studies. Specific atmospheric measurements were planned for each PROBA overpass on each day.

The activities planned over Barrax this summer originated from the combination of a number of initially not connected initiatives coming under different funding:

• Field activities in the framework of the EU project DEMETER,
• MERIS / ASAR synergy studies within an ENVISAT AO project,
• MERIS validation activities within the framework of another ESA project,
• CHRIS/PROBA acquisitions and data analysis under the framework of another initiative,
• MSG/SEVIRI validation activities under funding by EUMETSAT LSA SAF,
• Barrax as an additional site for VALERI activities,
• background activities for vegetation fluorescence modeling and validation studies,
• background activities for SPECTRA studies,
• and others.

Moreover, parallel activities related to definition of core sites for satellite validations for CHRIS and ENVISAT data have motivated the interest in getting involved in this activity by other people, with activities also related to AATSR and ASTER thermal data validation. Other team will come from Tunisia to participate in the campaign under the Spain-Tunisia bilateral agreements for cultural/scientific cooperation. The planned tests of the airborne vegetation fluorimeter under construction were not possible during this campaign because the instrument was not yet available, but the technological component of the campaign consisted on the testing of new electro-acoustic detectors for potential use in hyperspectral remote sensing applications (from another EU project). At the end, the activities became relevant enough to go one step forward and try to convert the independent activities into a more coherent program.

For this reason, it was suggested to ESA to convert the different unconnected activities planned in Barrax for this summer into a formal ESA campaign, under the framework of SPECTRA related activities. This idea was accepted, and a formal ESA contract has been established for this campaign.

For MERIS it was only possible to get Full Resolution data for one day during the campaign, 14 July, but at least this image is successfully available:

With the addition of the airborne component provided by the ESA support, the scaling from ground measurements to the SEVIRI resolution can now be done in with the following progression:

1. Field measurements --->
2. ROSIS (1 m) --->
3. HYMAP (5 m) --->
4. CHRIS (34 m) --->
5. MERIS FR (300 m) --->
6. MERIS RR (1200 m) --->
7. SEVIRI.

Concerning atmospheric measurements, we launched 2 radiosounding balloons every day of the campaign, one in the early morning (to get stable atmospheric condition) and the other just at the time of satellite/aircraft overpass. The combination of radiosoundings / lidar / sunphotometers / high spectral resolution sky radiance measurements will allow to address a number of issues such as:

1. Aerosols optical thickness retrievals (more related aerosols parameters), by different methods and techniques.
2. Atmospheric correction of the satellite data, with several algorithms to be tested for CHRIS and MERIS.
3. High spectral resolution radiance measurements in the O2-A band for validation of MERIS pressure retrievals for Rayleigh corrections.

Vegetation measurements focused on three main parameters: LAI, fCover, Chlorophyll. These three parameters are the official products being validated in the context of MERIS and SEVIRI activities. Obviously, for validation, it was convenient to measure additional information about canopy architecture: canopy height, leaf size, etc. and other relevant information about phenology of each type of crop. Radiometric measurements at the leaf and canopy levels were performed by using the several available radiometers with different fields of view and different setups. Different methods to measure LAI and chlorophyll were used, as well as for fCover, including regular, hemispheric and stereoscopic digital photos. Some intercomparison of methods was done, as planned, but more will be done.

Maps of the status of vegetation were prepared as part of the background DEMETER activities already on going, and other satellite data (Landsat) were also available as part of the DEMETER project. Since we had already performed two other airborne campaigns this year in Barrax for the TerraSAR program, some aspects of the campaign preparations were well advanced.