Remote-sensing technologies are a pillar of many Earth observation applications, e.g. climate monitoring, weather forecasting, biodiversity tracking, land-use change monitoring, natural disaster monitoring, natural resources management, etc. The increasing sophistication of satellite remote-sensing gives nowadays access to highly accurate radiometric data meeting requirements for Earth observation applications, e.g. around 2 to 3 % relative radiometric accuracy for radiometers on-board Sentinel satellites.
For climate monitoring purposes, precision and trueness of these radiometric data must be routinely monitored over long periods of time. This is critical to proper assessment of possible sources of uncertainty in the collected data, i.e. to propagate uncertainty from the observations up to the delivered geophysical products and associated data. These activities heavily rely on ground-based observations often acquired at different temporal, spatial and spectral resolutions. Thus, ground observations cannot be straightforwardly compared with similar space-based derived products. Therefore, complex radiative transfer simulation tools are necessary to understand to what extent these two types of measurements can be compared, accounting for their respective uncertainties.
The compartmentalisation of the Earth observation community into specialised subcommunities led to the simultaneous development of radiative transfer models and simulation software packages, each addressing their specific problem and therefore shipping specific physical and programming features and data sets. No tool currently allows to merge all the resulting scientific advances into a single software package to tackle heavily coupled radiative problems. This is the problem Eradiate aims to address.
A flexible 3D radiative transfer model #
Eradiate aims at providing a flexible framework for activities related with calibration and validation in the Earth observation community, where flexibility is to be understood in various ways.
Flexibility in physical complexity. Increasing the level of realism by accounting for more complex physics should be a burden for the computer, not for the physicist. Eradiate allows to enable or disable physical features without changing other input.
Flexibility in scene complexity. Radiative transfer model users have different needs when it comes to defining a scene on which to perform radiative transfer simulation. Some may need simple one-dimensional atmospheric model to quickly evaluate a radiative flux; others may need to represent each tree leaf of a forest; and some may need both at the same time! Eradiate provides a unified scene construction interface which allows to naturally populate a scene with simple or complex objects, and to combine both.
Flexibility in usage. Eradiate is fully scriptable. Its high-level experiment models provide a user-friendly programmatic interface ideal for usage in interactive Python sessions. Experienced users can use the low-level components to build their own solution.
A bridge between communities #
One goal is to break boundaries between the Earth observation subcommunities and help them share their scientific advances. We want to make it easy for scientists to improve the accuracy of their numerical simulations by accounting for radiative coupling. For that purpose, Eradiate ship models and algorithms originating from the subcommunities with a common interface. Adding a standard atmosphere profile on top of a detailed forest canopy should not be a painful endeavour, nor should be adding a standard desert surface underneath a complex cloud.
Long-term maintenance #
Eradiate is to be maintained on the long term. This means that it is carefully designed and coded with rigorous style and processes. It is also throroughly tested and validated through documented tests and benchmarks. It is shipped with comprehensive and thorough documentation.
A community-oriented development scheme #
Since Eradiate is meant to be a simulation tool for the scientific community, it is released under an open-source license. Contribution to the development by the scientific and user community is encouraged through a discussion forum and the review of issues and pull requests.
Our long-term goal is to structure Eradiate as a core package which defines common interfaces, documentation frameworks, core RTE solvers and evaluation protocols, on which specialised modules dedicated to specific user communities or applications can depend.
Funding and development history #
- The development and maintenance of Eradiate are funded by the Copernicus programme through a project managed by the European Space Agency (contract no 40000127201/19/I‑BG).
- The design phase was funded by the MetEOC-3 project (EMPIR grant 16ENV03).
- Eradiate is currently maintained by Brussels-based company Rayference.
‘Eradiate’ is an uncommon English word for ‘radiate’. This name was chosen among a dozen of candidates using the majority judgement voting method proposed by mathematicians Michel Balinski and Rida Laraki.