Landsat 8 Uncertainty
Landsat 8 Pre-Launch
The radiometric calibration of Landsat 8’s Operational Land Imager (OLI) is required to be metrologically traceable to the standards set by the National Institute of Standards and Technology (NIST). The USGS calibration sources used before the satellite’s launch were to be calibrated to NIST radiance and reflectance standards, and their calibration were to be transferred to at least one on-board calibration device that would remain radiometrically stable through launch.
The absolute radiometric radiance and reflectance calibration uncertainties were required to be ±5 percent (1 sigma or k = 1) and ±3 percent (k = 1), respectively, for the radiance range of LTypical to 0.9*LMax (Table 1).
For any other radiance across the range of 0.3*LTypical to LTypical the absolute uncertainties were not to exceed the above values by more than 0.5 percent. This requirement applies to extended, spatially uniform, unpolarized targets with a known spectral shape.
Table 1: Typical and maximum OLI radiances
| Band |
Radiance Level, L
(W/m2 sr µm) |
Saturation Radiances,
LMax (W/m2 sr µm) |
| Typical, LTypical |
High, LHigh |
Requirement |
| 1 - Coastal Aerosol |
40 |
190 |
555 |
| 2-Blue |
40 |
190 |
581 |
| 3-Green |
30 |
194 |
544 |
| 4-Red |
22 |
150 |
462 |
| 5-Near Infrared |
14 |
150 |
281 |
| 6-SWIR 1 |
4.0 |
32 |
71.3 |
| 7-SWIR 2 |
1.7 |
11 |
24.3 |
| 8-Panchromatic |
23 |
156 |
515 |
| 9-Cirrus |
6.0 |
N/A |
88.5 |
The transfer of radiometric calibration from NIST sources to OLI and the acquired Earth image data can be impacted by various effects and their uncertainties such as spectral response, nonlinearity, nonuniformity, stray light, any transmissive elements, and radiance sources and their stability.
By combining the uncertainties, OLI manufacturer Ball Aerospace estimated total radiance uncertainty to less than 3.5 percent, 1-sigma, and total reflectance uncertainty to less than 2.5 percent, 1-sigma, at the end of life at typical and higher radiance levels for every spectral band. The total uncertainty estimates for per-band calibration transfer for two radiance ranges: LTypical to 0.9*LMax and 0.3*LTypical to LTypical are shown in Table 2.
Table 2: Landsat 8 OLI pre-launch per-band radiometric uncertainty estimates. (Values = %)
| |
Radiance |
Reflectance |
| Band |
High Radiance
( LTyp- 0.9*LMax ) |
Low Radiance
(0.3* LTyp- LTyp ) |
High Radiance
( LTyp- 0.9*LMax ) |
Low Radiance
(0.3* LTyp- LTyp ) |
| 1- Coastal Aerosol |
3.4 |
3.7 |
2.1 |
2.7 |
| 2-Blue |
3.1 |
3.4 |
1.9 |
2.6 |
| 3-Green |
3.0 |
3.3 |
1.7 |
2.5 |
| 4-Red |
2.9 |
3.2 |
1.7 |
2.4 |
| 5-NIR |
3.0 |
3.3 |
1.7 |
2.4 |
| 6-SWIR 1 |
3.3 |
3.7 |
2.2 |
2.8 |
| 7-SWIR 2 |
3.2 |
3.6 |
2.0 |
2.6 |
| 8-Panchromatic |
3.4 |
3.7 |
1.7 |
2.5 |
| 9-Cirrus |
4.1 |
4.5 |
2.3 |
2.8 |
