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Crop Agriculture

About Landsat 8 (Landsat Data Continuity Mission [LDCM]); Refinements

February 11, 2013, successful launch

Landsat 8 had a successful launch February 11th; the satellite has many refinements plus new bands. If the satellite operates successfully, there will be ongoing imaging for the years ahead. Due to the challenges and complexity of successful satellite imaging, ongoing imagery is by no means assured. For example, of the last three Landsats, Landsat 7 reached orbit but in 2003 incurred a problem that created ongoing stripings of missing data on imagery, Landsat 6 did not reach orbit, while Landsat 5 operated successfully well beyond its expectancy.

 New benefit for crop imaging: Landsat 8 refined NIR bandwidth and 12-bit dynamic range

Previous Landsats provide an 8-bit range (256 levels) of pixel values; Landsat 8 provides a 12-bit range (4,096 levels) of pixel values, improving precision.

The USGS posted Landsat band designations in 2013 that are slightly different than those shown from the brochure below; the slightly different Landsat band designations can be accessed here.

Graphic below from NASA/USGS (2012); brochure can be accessed here (pdf)

Landsat 8 refined NIR bandwidth and 12-bit dynamic range

Landsat 8 NIR bandwidth is improved compared to previous Landsat satellites, in part, because NIR radiation will not get absorbed as much by atmospheric precipitable water. When studying Quickbird imagery (has the same NIR bandwidth as Landsat 5 and virtually the same as Landsat 7), Wu et al. (2005) developed an adjustment method to offset the absorption of NIR radiation by total atmospheric precipitable water to retrieve accurate enough reflectance. The refinement of the Landsat 8 NIR bandwidth helps solve this problem. Landsat 7 NIR (band 4) bandwidth is 0.775–0.900 µm while Landsat 8 NIR (band 5) bandwidth 0.845–0.885 µm. Landsat 8 NIR is in much more of an atmospheric window in regards to absorption by water. The following articles describe water absorption of NIR radiation.

Precipitable water effect on NIR radiation articles

 

Figures 2 and 3 from Guzzi and Rizzi (1984; can be accessed through above link)

Atmospheric precipitable water effect on NIR radiation

Table II from Eldridge (1967; can be accessed through above link) 

Atmospheric transmittance through water vapor

 

 References

Eldridge, R.G. 1969. Water vapor absorption of visible and near infrared radiation. Applied Optics, Vol. 6, No. 4: pp. 709-713.

Guzzi, R., and R. Rizzi. 1984. Water vapor absorption in the visible and near infrared: results of field measurements. Applied Optics, Vol. 23, No. 11: pp. 1853-1861.

NASA/USGS. 2012. Landsat Data Continuity Mission: brochure.  NASA and USGS.

Wu, J., Wang, D., and M.E. Bauer. 2005. Image-based atmospheric correction of Quickbird imagery of Minnesota cropland. Remote Sensing of Environment 99: pp.315-325.