The main objective of Earth Observation Campaigns is to provide support for the preparation of future space programmes and their users. The programme of campaign activities includes support for experiments related to atmospheric dynamics, atmospheric chemistry, coasts and oceans, ice and the land.
Instruments include lidars, nadir sounding spectrometers, limb sounding interferometers and microwave limb sounders that have capabilities for measuring atmospheric chemical composition and dynamics. Instruments for the observation of the ocean and land include high-resolution spectral imagers, advanced SARs, microwave radiometers and altimeters.
Another important objective is the validation of satellite data products against independent measurements. This requires field campaigns using instruments on land, on ships, on aircraft and balloons in order to make a variety of in-situ measurements of surface and atmospheric variables.
Many of the requirements for campaigns come from ESA advisory groups supporting current missions in orbit as well as future missions.
Why Earth Observation Campaigns are needed
Campaigns are required to:
- Explore Earth observation possibilities
- Prove concepts
- Develop interpretation
- Develop calibration
- Simulate data products
- Validate results
Before embarking on a large Earth observation mission in space it is necessary to verify that the instrument being considered is capable of providing the remotely sensed information needed to the accuracy required. This cannot always be done by scientific studies alone. Real data, measurements and images acquired by airborne sensors, ground-based equipment and/or laboratory instruments are needed.
During the development phase of a typical mission, campaign data are needed for the development of interpretation methods, calibration concepts and the refinement of processing algorithms. During the operational phase when the satellite is in orbit, campaigns are needed for the validation of the satellite data products.
Campaign requirements are associated with different objectives for technology, geophysical modelling, simulation and validation.
The main technological requirements for campaigns are testing new technologies from aircraft platforms and the improvement of performance specifications for future space-borne missions. New technologies tested on airborne platforms and from ground sites include multi-band, polarimetric SARs, SAR interferometers, imaging spectrometers, microwave radiometers, radar altimeters, microwave limb sounders, lidars, and rain/cloud radar. Data from the corresponding campaigns are used to assist in the specification of future space-borne instruments, algorithm development and planning validation.
The main objective of geophysical modelling is the development of operational algorithms for the so-called Level-2 products from space-borne sensors. Level-2 products are obtained through a conversion from calibrated sensor outputs in terms of physical variables (backscatter coefficient, reflectance, brightness temperature) to target characteristics (ocean wind and waves, suspended matter, biomass and soil moisture on land, trace gas concentration in the atmosphere). The development of Level-2 products is difficult and takes time. It involves a learning process both inside the Agency and within the potential user community. Its importance however, cannot be easily overestimated
Simulation is aimed at providing data sets to ESA engineers and the scientific and applications user community for training and testing purposes. In many applications the end user can only be satisfied with higher than Level-2 products, whereby the Level-2 product is merged (assimilated) with other, non-satellite data. Campaigns have proven to be the ideal vehicle for involving the end-user community in the early development of these assimilation schemes. A number of remote sensing data sets have been collected in conjunction with the associated ground data. These include the following:
ERS radar data, airborne radar data and microwave radiometer data in a number of wavebands over:
Semi arid zones (SAHEL)
Snow and ice
Optical spectroscopy data over:
Lidar data both from space and from land stations of various clouds, ocean and land surfaces
- Ground-based radar observations of rain and clouds
After initial analysis of these data sets as reported during the final campaign workshops, the data are available as inputs for future mission definition studies and algorithm development work.
Calibration and validation
Following internationally agreed definitions, instrument and data calibration involves pre-launch and post-launch measurements to fully characterise the payload instruments and subsequent activities to configure the ground processors to provide calibrated (Level 1b) data products (radiance, reflectance, transmittance, polarisation, radar backscattering coefficient, radar echo-time delay). Geophysical calibration and validation is a process whereby geophysical data products (Level 2) are derived from the Level 1 data products and checked against independent (in-situ) measurements of the relevant geophysical variables. These include atmospheric variables (temperature, pressure, atmospheric constituents, aerosol and cloud parameters), marine variables (ocean surface wind and waves, ocean colour, sea surface temperature, sea-ice thickness, ocean salinity) and land variables (vegetation index, temperature, pressure and reflectance). For each geophysical data product, a number of different in-situ measurements have to be made by ground-based, airborne and balloon-borne instruments. After the commissioning phase of a typical mission, the validation programme will make a quality assessment of the geophysical data products and will recommend re-calibration and algorithm development as appropriate.
Last update: 13 September 2011