Landsat
General
Product packaging
L08/L09 Collection 2
LXSS_LLLL_PPPRRR_YYYYMMDD_yyyymmdd_CX_TX (e.g., LC08_L2SP_039037_20150728_20200318_02_T1)
| L | Landsat |
|---|---|
| X | Sensor (“O” = OLI; “T” = TIRS; “C” = OLI/TIRS) |
| SS | Satellite (“08” = Landsat 8, “09” = Landsat 9) |
| LLLL | Processing correction level (“L2SP” if SR and ST are generated or “L2SR” if ST could not be generated) |
| PPP | Path |
| RRR | Row |
| YYYY | Year of acquisition |
| MM | Month of acquisition |
| DD | Day of acquisition |
| yyyy | Year of Level 2 processing |
| mm | Month of Level 2 processing |
| dd | Day of Level 2 processing |
| CX | Collection number (“02”) |
| TX | Collection category (“T1” = Tier 1; “T2” = Tier 2) |
Collection 2 Tiers
Landsat Collection Tiers are the inventory structure for Level-1 data products and are based on data quality and level of processing. The tier definition purpose is to support easier identification of suitable scenes for time-series pixel-level analysis, and provide temporary data that are processed immediately upon downlink to be dispensed quickly in emergency response situations with limited calibration.
Newly acquired Landsat 9 OLI/TIRS data are processed into Tier 1 or Tier 2, and become available for download 4-6 hours after Level-1 product generation.
Newly acquired Landsat 8 OLI/TIRS data are processed using initial TIRS line-of-sight model parameters, are placed in the Real-Time (RT) tier, and made available for download 4-6 hours after Level-1 product generation. Landsat 8 TIRS data may not meet specifications for co-registration with OLI. Landsat 8 TIRS line-of-sight model parameters are refined based on data acquired during biweekly calibration maneuvers and scenes are reprocessed within 14 to 16 days of acquisition and moved into Tier 1 or Tier 2.
The Tier designation (T1, T2, RT) is visible at the end of the Landsat Product Identifier, as shown in the examples below. It is also provided as an additional metadata field in EarthExplorer. Note: Historical Landsat 4-5 TM and Landsat 7 ETM+ data received from International Ground Stations supporting the Landsat Global Archive Consolidation effort are placed in either Tier 1 or Tier 2 after Collection 1 processing.
- Real-Time: LC08_L1TP_013002_20200629_20200629_01_RT
- Tier 1: LC08_L1TP_013042_20211225_20211230_02_T1
- Tier 2: LT05_L1GS_178058_19950410_20200912_02_T2
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Tier 1 (T1)
Landsat scenes with the highest available data quality are placed into Tier 1 and are considered suitable for time-series analysis. Tier 1 includes Level-1 Precision and Terrain (L1TP) corrected data that have well-characterized radiometry and are inter-calibrated across the different Landsat instruments. The georegistration of Tier 1 scenes is consistent and within prescribed image-to-image tolerances of ≦ 12-meter radial root mean square error (RMSE).
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Tier 2 (T2)
Landsat scenes not meeting Tier 1 criteria during processing are assigned to Tier 2. Tier 2 scenes adhere to the same radiometric standard as Tier 1 scenes, but do not meet the Tier 1 geometry specification due to less accurate orbital information (specific to older Landsat sensors), significant cloud cover, insufficient ground control, or other factors. This includes Systematic Terrain (L1GT) and Systematic (L1GS) processed data. Users interested in Tier 2 scenes can query the RMSE and other properties to determine their application suitability.
Acquisition time
Landsat 8 and Landsat 9 cross the equator at 10:00 a.m. +/- 15 minutes (mean local time).
This will be referred to as SCENE_CENTER_TIME in the metadata file, and as datetime for STAC items. The format will be in UTC+0:00 time and translate to GMT+0:00. To convert to the localized time, the offset of the timezone is needed.
Cloud masking
// 30 := 0b11110 (dilated cloud, cirrus, cloud, cloud shadow)
mask = QA & 30
good = where mask == 0
Conversions
For Landsat-8 the required metadata for the following formulas are available under *MTL.txt
Digital Numbers (DN) to Top of Atmosphere (ToA) Spectral Radiance Value
Used for surface temperature estimation.
\[ L_{\lambda} = M_L Q_{cal} + A_l \]
Where:
\(L_{\lambda}\) = TOA spectral radiance \((Watts / m2 \times srad \times \mu m)\)
\(M_L\) = Band specific multiplicative rescaling factor from metadata (RADIANCE_MULT_BAND_x, where x is the band number)
\(A_L\) = Band-specific additive rescaling factor from the metadata (RADIANCE_ADD_BAND_x, where x is band number)
\(Q_{cal}\) = Quantized and calibrated standard product values (
ToA Radiance to at-satellite brightness temperature
\[ T = \frac{K_2}{ln(\frac{K_1}{L_{\lambda}} + 1)} \]
Where:
\(T\) = At-satellite brightness temperature (\(K\))
\(L_{\lambda}\) = TOA spectral radiance \((Watts / m2 \times srad \times \mu m)\)
\(K_1\) = Band-specific thermal conversion constant from the metadata (K1_CONSTANT_BAND_x, where x is the thermal band number)
\(K_2\) = Band-specific thermal conversion constant from the metadata (K2_CONSTANT_BAND_x, where x is the thermal band number)
At-satellite brightness temperature is an estimation of the land surface temperature. True land surface temperature would need further adjustment based on the emissivity of the type of land cover.