Geographic Information Systems Asked by user5858 on August 10, 2020
I’m doing a temporal analysis of NDVI and temperature over 17 years, necessitating data from Landsat 5,7, & 8. I’m interested in using level-2 Landsat data available from https://espa.cr.usgs.gov/ordering/new/. I would be able to directly download NDVI as well as brightness temperature, which would save me a lot of time. However, the USGS is explicit that the algorithm used to calculate surface reflectance for Landsat 8 is not the same as the algorithm used for previous satellites.
https://landsat.usgs.gov/landsat-surface-reflectance-high-level-data-products
My question is: are the level-2 products from Landsat-8 comparable on an apples-to-apples basis with Landsat 5 or 7 level-2 products, or does this kind of comparison require some sort of adjustment to the data? I haven’t been able to find an answer to this question online.
Yes, you do need to correct Landsat 8 imagery to compare it against Landsat 5 and 7. The data between the three satellites are not directly comparable in their raw form.
This paper compares Landsat 7 to Landsat 8:
Roy, D.p., et al. “Characterization of Landsat-7 to Landsat-8 Reflective Wavelength and Normalized Difference Vegetation Index Continuity.” Remote Sensing of Environment, vol. 185, 2016, pp. 57–70., doi:10.1016/j.rse.2015.12.024.
For instance, from the paper, to compare Landsat 8 NDVI with Landsat 7 NDVI you need to apply the following correction to the Landsat 8 NDVI:
L7NDVI = 0.0029+0.9589*L8NDVI
Further, this paper shows that Landsat 7 NDVI is about 2.5% higher than Landsat 5 NDVI:
Teillet, P M, et al. “Landsat-7 ETM+ and Landsat-5 TM Cross-Calibration Based on Tandem Data Sets.” Remote Sensing of Environment, vol. 78, no. 1-2, 2000, pp. 39–54., doi:10.4095/219729.
Correct answer by user5858 on August 10, 2020
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