Field scale wheat LAI retrieval from multispectral Sentinel 2A-MSI and LandSat 8-OLI imagery: effect of atmospheric correction, image resolutions and inversion techniques

Abstract

This study assessed the effect of atmospheric correction algorithms, inversion techniques and image spatial and spectral resolution on wheat crop LAI retrieval using Sentinel-2 MSI and Landsat-8 OLI imagery. The LAI retrievals were validated with in-situ measurements collected in farmers’ fields. The MSI-based LAI retrievals improved significantly when images were atmospherically corrected using MODTRAN than using the libRadtran code. Among the two PROSAIL inversion approaches, look-up table outperforms artificial neural network for LAI retrievals. Using the best strategy of atmospheric correction and inversion, the effect of spatial resolution from 20 m (MSI) to 30 m (OLI) while using common six bands, showed non-significant improvement in LAI retrievals. The inclusion of additional two red-edge bands as available in MSI significantly reduced the uncertainly in LAI retrievals over that obtained by using six bands, while inclusion of only additional VNIR band did not show any significant effect on LAI retrievals.

Keywords:

• Crop
• PROSAIL
• inversion
• spatial resolution
• spectral resolution

Acknowledgements

The first author acknowledges his employer for granting study leave to undertake PhD. Authors acknowledge the research facilities extended by Head, Division of Agricultural Physics, ICAR - Indian Agricultural Research Institute, New Delhi.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded by ICAR-National Innovations on Climate Resilient Agriculture (NICRA) project and IARI in-house project [CRSCIARISIL2014028260].