Effects that act together
Objective
Learn how effects combine, such as illumination geometry and atmospheric water vapour acting together, wherever the evidence supports it.
Scoped How stages are defined
Effects do not simply add. The path through the atmosphere lengthens with sun and view angle, so the imprint of water vapour absorption changes with geometry. A model that treats each effect in isolation is least accurate exactly where conditions differ most from the average.
Real acquisitions are made under combinations of conditions: low sun over humid terrain, steep viewing angles in dry air. Results have to hold across those combinations, not only near typical conditions.
We use observations that span different combinations of geometry and moisture, compare predictions made with and without the combined effect, and test those predictions on combinations that played no part in learning it.
The combined effect predicts measurements under new combinations of conditions better than the separate effects alone, and remains distinct from every other effect in the description.
Established work this area builds on. Results from the programme are published separately, with their data and limits.
- Learning about physical parameters: the importance of model discrepancy (2014) J. Brynjarsdottir and A. O'Hagan Why an extra term that improves a fit is not evidence of a real physical effect.
Questions about this work?
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