- Title
- Time delay evaluation on the water-leaving irradiance retrieved from empirical models and satellite imagery
- Creator
- Otto, Peter; Vallejo-Rodríguez, Ramiro; Keesstra, Saskia; León-Becerril, Elizabeth; de Anda, Josè; Hernández-Mena, Leonel; del Real-Olvera, Jorge; de Jesús Díaz-Torres, Josè
- Relation
- Remote Sensing Vol. 12, Issue 1, no. 87
- Publisher Link
- http://dx.doi.org/10.3390/RS12010087
- Publisher
- MDPI AG
- Resource Type
- journal article
- Date
- 2020
- Description
- Temporal delays and spatial randomness between ground-based data and satellite overpass involve important deviations between the empirical model output and real data; these are factors poorly considered in the model calibration. The inorganic matter-generated turbidity in Lake Chapala (Mexico) was taken as a study case to expose the influence of such factors. Ground-based data from this study and historical records were used as references. We take advantage of the at-surface reflectance from Landsat-8, sun-glint corrections, a reduced NIR-band range, and null organic matter incidence in these wavelengths to diminish the physical phenomena-related radiometric artifacts; leaving the spatio-temporal relationships as the principal factor inducing the model uncertainty. Non-linear correlations were assessed to calibrate the best empirical model; none of them presented a strong relationship (<73%), including that based on hourly delays. This last model had the best predictability only for the summer-fall season, explaining 71% of the turbidity variation in 2016, and 59% in 2017, with RMSEs < 24%. The instantaneous turbidity maps depicted the hydrodynamic complexity of the lake, highlighting a strong component of spatial randomness associated with the temporal delays. Reasonably, robust empirical models will be developed if several dates and sampling-sites are synchronized with more satellite overpasses.
- Subject
- temporal delay; spatial randomness; empirical model; turbidity; Landsat-8; NIR reflectance
- Identifier
- http://hdl.handle.net/1959.13/1440280
- Identifier
- uon:41113
- Identifier
- ISSN:2072-4292
- Language
- eng
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