Landsat Collection 2 Level-2 Surface Temperature

Date modified: 23 August 2021

Product overview

Background

Digital Earth Africa (DE Africa) provides free and open access to a copy of Landsat Collection 2 Level-2 products over Africa. These products are produced and provided by the United States Geological Survey (USGS).

The Landsat series of Earth Observation satellites, jointly led by USGS and NASA, have been continuously acquiring images of the Earth’s land surface since 1972. DE Africa provides data from Landsat 5, 7 and 8 satellites, including historical observations dating back to late 1980s and regularly updated new acquisitions.

New Level-2 Landsat 7 and Landsat 8 data are available after 15 to 27 days from acquisition. See Landsat Collection 2 Generation Timeline for details.

USGS Landsat Collection 2 was released early 2021 and offers improved processing, geometric accuracy, and radiometric calibration compared to previous Collection 1 products. The Level-2 products are endorsed by the Committee on Earth Observation Satellites (CEOS) to be Analysis Ready Data for Land (CARD4L)-compliant. This internationally-recognised certification ensures these products have been processed to a minimum set of requirements and organised into a form that allows immediate analysis with a minimum of additional user effort and interoperability both through time and with other datasets.

USGS Landsat Collection 2 Level-2 includes:

  • Surface Reflectance

  • Surface Temperature

This document provides technical specifications for the Surface Temperature product. Information for the Surface Refletance product can be found in the Landsat Collection 2 Level-2 Surface Reflectance specification.

Surface temperature measures the Earth’s surface temperature and is an important geophysical parameter in global energy balance studies and hydrologic modeling. Surface temperature is also useful for monitoring crop and vegetation health, and extreme heat events such as natural disasters (e.g., volcanic eruptions, wildfires), and urban heat island effects.

Specifications

Spatial and temporal coverage

DE Africa provides Landsat Collection 2 Level-2 from Landsat 5, 7 and 8 as seperate products. Relevant coverage and metadata can be viewed on DE Africa Metadata Exploer:

Table 1: Landsat Collection 2 Level-2 Surface Temperature product specifications

Satellite

Landsat 5

Landsat 7

Landsat 8

Instrument

Multispectral Scanner (MSS), Thematic Mapper (TM)

Enhanced Thematic Mapper (ETM+)

Operational Land Imager (OLI), Thermal Infrared Sensor (TIRS)

Number of bands

11

11

11

Cell size - X (metres)

30

30

30

Cell size - Y (metres)

30

30

30

Coordinate reference system

Universal Transverse Mercator (UTM)

UTM

UTM

Temporal resolution

Every 16 days

Every 16 days

Every 16 days

Temporal range

1984 – 2012

1999 – present

2013 – present

Parent dataset

Landsat Collection 2 Level-1

Landsat Collection 2 Level-1

Landsat Collection 2 Level-1

Update frequency

NA (archive)

Daily

Daily

Measurements

Table 2: Landsat 5 and Landsat 7 Surface Temperature Level-2 measurements

Band ID

Description

Units

Range

Data type

No data\(^\dagger\)

Conversion\(^\ddagger\)

ST_B6

Surface temperature band 6 (Thermal Infrared (TIR))

Kelvin

1-65535

uint16

0

0.00341802 * DN + 149.0

ST_TRAD

Thermal radiance

Wm\(^{-2}\)sr\(^{-1}\)\(\mu\)m\(^{-1}\)

0-22000

int16

-9999

0.001 * DN

ST_URAD

Upwell radiance

Wm\(^{-2}\)sr\(^{-1}\)\(\mu\)m\(^{-1}\)

0-28000

int16

-9999

0.001 * DN

ST_DRAD

Downwell radiance

Wm\(^{-2}\)sr\(^{-1}\)\(\mu\)m\(^{-1}\)

0-28000

int16

-9999

0.001 * DN

ST_ATRAN

Atmospheric transmittance

Unitless

0-10000

int16

-9999

0.0001 * DN

ST_EMIS

Emissivity

Unitless

0-10000

int16

-9999

0.0001 * DN

ST_EMSD

Emissivity standard deviation

Unitless

0-10000

int16

-9999

0.0001 * DN

ST_CDIST

Distance to cloud

Kilometers

0-24000

int16

-9999

0.01 * DN

QA_PIXEL

Pixel quality

Bit Index

0-65535

uint16

1

NA

QA_RADSAT

Radiometric saturation

Bit Index

0-65535

uint16

0

NA

ST_QA

Surface temperature uncertainty

Kelvin

0-32767

int16

-9999

0.01 * DN

\(^\dagger\) No data or fill value.

\(^\ddagger\) Physical measurement can be derived from the Digital Number (DN) stored in the product using the conversion equation listed.

More inforamtion can be found from the Landsat 4-7 Collection 2 Science Product Guide.

Table 3: Landsat 8 Level-2 Surface Temperature measurements

Landsat 8 Level-2 science product is generated using a different algorithm and has different output measurements compared to Landsat 5 and Landsat 7.

Band ID

Description

Units

Range

Data type

No data\(^\dagger\)

Conversion\(^\ddagger\)

ST_B10

Surface temperature band 10 (TIR)

Kelvin

1-65535

uint16

0

0.00341802 * DN + 149.0

ST_TRAD

Thermal radiance

Wm\(^{-2}\)sr\(^{-1}\)\(\mu\)m\(^{-1}\)

0-22000

int16

-9999

0.001 * DN

ST_URAD

Upwell radiance

Wm\(^{-2}\)sr\(^{-1}\)\(\mu\)m\(^{-1}\)

0-28000

int16

-9999

0.001 * DN

ST_DRAD

Downwell radiance

Wm\(^{-2}\)sr\(^{-1}\)\(\mu\)m\(^{-1}\)

0-28000

int16

-9999

0.001 * DN

ST_ATRAN

Atmospheric transmittance

Unitless

0-10000

int16

-9999

0.0001 * DN

ST_EMIS

Emissivity

Unitless

0-10000

int16

-9999

0.0001 * DN

ST_EMSD

Emissivity standard deviation

Unitless

0-10000

int16

-9999

0.0001 * DN

ST_CDIST

Distance to cloud

Kilometers

0-24000

int16

-9999

0.01 * DN

QA_PIXEL

Pixel quality

Bit Index

0-65535

uint16

1

NA

QA_RADSAT

Radiometric saturation

Bit Index

0-65535

uint16

0

NA

ST_QA

Surface temperature uncertainty

Kelvin

0-32767

int16

-9999

0.01 * DN

\(^\dagger\) No data or fill value.

\(^\ddagger\) Physical measurement can be derived from the Digital Number (DN) stored in the product using the conversion equation listed.

More inforamtion can be found from Landsat 8 OLI/TIRS Collection 2 Science Product Guide and Landsat 8-9 OLI/TIRS Collection 2 Level 2 Data Format Control Book

Quality assessment bands

Pixel quality assessment (QA_PIXEL) bands for Landsat 5, 7 and 8 are generated by the CFMask algorithm. Different bit definitions are used because the cirrus band is only available on Landsat 8. This band is relevant to both Surface Reflectance and Surface Temperature products.

Table 4: Pixel quality assessment (QA_PIXEL) bit index.

Bit

Landat 5 & 7

Landsat 8

Description Values

0

Fill

Fill

0 for image data; 1 for fill data

1

Dilated Cloud

Dilated Cloud

0 for cloud is not dilated or no cloud; 1 for cloud dilation

2

Unused

Cirrus

0 for cirrus confidence is not; 1 for high confidence cirrus

3

Cloud

Cloud

0 for cloud confidence is not high; 1 for high confidence cloud

4

Cloud Shadow

Cloud Shadow

0 for Cloud Shadow Confidence is not high; 1 for high confidence cloud shadow

5

Snow

Snow

0 for Snow/Ice Confidence is not high; 1 for high confidence snow cover

6

Clear

Clear

0 if Cloud or Dilated Cloud bits are set; 1 if Cloud and Dilated Cloud bits are not set

7

Water

Water

0 for land or cloud; 1 for water

8-9

Cloud Confidence

Cloud Confidence

00 for no confidence level set; 01 Low confidence; 10 Medium confidence; 11 High confidence

10-11

Cloud Shadow Confidence

Cloud Shadow Confidence

00 for no confidence level set; 01 Low confidence; 10 Reserved; 11 High confidence

12-13

Snow/Ice Confidence

Snow/Ice Confidence

00 for no confidence level set; 01 Low confidence; 10 Reserved; 11 High confidence

14-15

Unused

Cirrus Confidence

00 for no confidence level set; 01 Low confidence; 10 Reserved; 11 High confidence

Radiometric saturation quality assessment (QA_RADSAT) bands are different for Landsat 5, 7 and 8 because the sensors have different spectral bands. This band is relevant to both Surface Reflectance and Surface Temperature products.

Table 5: Radiometric saturation quality assessment (QA_RADSAT) bit index.

Bit

Landsat 5

Landsat 7

Landsat 8

Description Values

0

Band 1 (Blue)

Band 1 (Blue)

Band 1 (Coastal)

0 no saturation; 1 saturated data

1

Band 2 (Green)

Band 2 (Green)

Band 2 (Blue)

0 no saturation; 1 saturated data

2

Band 3 (Red)

Band 3 (Red)

Band 3 (Green)

0 no saturation; 1 saturated data

3

Band 4 (NIR)

Band 4 (NIR)

Band 4 (Red)

0 no saturation; 1 saturated data

4

Band 5 (SWIR1)

Band 5 (SWIR1)

Band 5 (NIR)

0 no saturation; 1 saturated data

5

Band 6 (TIR)

Band 6L (TIR)†

Band 6 (SWIR1)

0 no saturation; 1 saturated data

6

Band 7 (SWIR2)

Band 7 (SWIR2)

Band 7 (SWIR2)

0 no saturation; 1 saturated data

7

Unused

Unused

Unused

0

8

Unused

Band 6H (TIR)‡

Band 9 (Cirrus)

0 no saturation; 1 saturated data

9

Dropped Pixel

Dropped Pixel

Unused

0 Pixel present; 1 detector doesn’t have a value – no data

10

Unused

Unused

Unused

0

11

Unused

Unused

Terrain occlusion

0 no terrain occlusion; 1 terrain occlusion

12

Unused

Unused

Unused

0

13

Unused

Unused

Unused

0

14

Unused

Unused

Unused

0

15

Unused

Unused

Unused

0

\(^\dagger\), \(^\ddagger\) For Landsat 7 products, the Band 6 TOA brightness temperature product is generated from ETM+ Band 6 High gain (6H) and Band 6 Low gain (6L) merged together. The merged Band 6 is comprised of pixels that are not saturated in Band 6H. When Band 6H pixels are saturated with a brightness temperature outside of the 6H dynamic range (from 240K to 322K), they will be filled with pixels from the 6L band even if those pixels are saturated.

Processing

Landsat Collection 2 Level-2 products are processed by the USGS from Collection 2 Level-1 inputs. Landsat 5, 7 and 8 surface temperature products are generated using the Landsat surface temperature algorithm.

Media and example images

Landsat surface temperature for Libya

Figure 1: Landsat false color composites (highlighting vegetation, top row) and corresponding surface temperature measurements (in Kelvin, bottom row) over an area in Tripoli District, Libya.

References

USGS Collection Level-2 website

License

There are no restrictions on Landsat data downloaded from the USGS; it can be used or redistributed as desired. USGS request that you include a statement of the data source when citing, copying, or reprinting USGS Landsat data or images.

Acknowledgements

Landsat Level- 2 Surface Temperature Science Product courtesy of the U.S. Geological Survey.

Data access

Amazon Web Services S3

Landsat Collection 2 Level-2 is available in AWS S3, sponsored by the Public Dataset Program.

Table 6: AWS data access details.

AWS S3 details

Bucket ARD

arn:aws:s3:::deafrica-landsat

Region

af-south-1

The bucket is in the AWS region af-south-1 (Cape Town). Additional region specifications can be applied as follows:

aws s3 ls --region=af-south-1 s3://deafrica-landsat/

The file paths follow the format collection02/level-2/standard/<sensor>/<year>/<path>/<row>/<scene_id>/.

Table 7: AWS file path convention.

File path element

Description

Example

sensor

Landsat sensor name, tm, etm or oli-tirs for landsat 5, 7 and 8

oli-tirs

year

Observation year

2021

path

Landsat orbit path id

172

row

Landsat orbit row id

057

scene_id

Landsat scene id

LC08_L2SP_172057_20210101_20210308_02_T1

OGC Web Services (OWS)

This product is available through DE Africa’s OWS.

Table 8: OWS data access details.

OWS details

Name

DE Africa Services

Web Map Services (WMS) URL

https://ows.digitalearth.africa/wms?version=1.3.0

Web Coverage Service (WCS) URL

https://ows.digitalearth.africa/wcs?version=2.1.0

Layer name

ls5_st, ls7_st, ls8_st

Digital Earth Africa OWS details can be found at https://ows.digitalearth.africa/.

For instructions on how to connect to OWS, see this tutorial.

Open Data Cube (ODC)

The Landsat Collection 2 Level-2 products can be accessed through the Digital Earth Africa ODC API, which is available through the Digital Earth Africa Sandbox.

ODC product names: ls5_st, ls7_st, ls8_st

Specific bands of data can be called by using either the default names or any of a band’s alternative names, as listed in the table below. ODC Datacube.load commands without specified bands will load all bands.

Table 9: Landsat 5 and Landsat 7 Level-2 Surface Temperature (ODC product ls5_st and ls7_st) band names.

Band name

Alternative names

Fill value

ST_B6

band_6, st, surface_temperature

0

ST_TRAD

trad, thermal_radiance

-9999

ST_URAD

urad, upwell_radiance

-9999

ST_DRAD

drad, downwell_radiance

-9999

ST_ATRAN

atran, atmospheric_transmittance

-9999

ST_EMIS

emis, emissivity

-9999

ST_EMSD

emsd, emissivity_stddev

-9999

ST_CDIST

cdist, cloud_distance

-9999

QA_PIXEL

pq, pixel_quality

1

QA_RADSAT

radsat, radiometric_saturation

0

ST_QA

st_qa, surface_temperature_quality

-9999

Table 10: Landsat 8 Level-2 Surface Temperature (ODC product ls8_st) band names.

Band name

Alternative names

Fill value

ST_B10

band_10, st, surface_temperature

0

ST_TRAD

trad, thermal_radiance

-9999

ST_URAD

urad, upwell_radiance

-9999

ST_DRAD

drad, downwell_radiance

-9999

ST_ATRAN

atran, atmospheric_transmittance

-9999

ST_EMIS

emis, emissivity

-9999

ST_EMSD

emsd, emissivity_stddev

-9999

ST_CDIST

cdist, cloud_distance

-9999

QA_PIXEL

pq, pixel_quality

1

QA_RADSAT

radsat, radiometric_saturation

0

ST_QA

st_qa, surface_temperature_quality

-9999

Band names are case-sensitive.

For examples on how to use the ODC API, see the DE Africa example notebook repository.

Technical information

Surface Temperature

The surface temperature product is generated from the Landsat Collection 2 Level-1 thermal infrared bands, Top of Atmosphere (TOA) reflectance, TOA brightness temperature, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Emissivity Database (GED) data, ASTER Normalized Difference Vegetation Index (NDVI) data, and atmospheric profiles of geopotential height, specific humidity, and air temperature extracted from Goddard Earth Observing System (GEOS) Model Version 5 Forward Processing Instrument Teams (FP-IT) (for acquisitions from 2000 to present) or Modern Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) (for acquisitions from 1982 to 1999).

For more information and caveats of the product, visit the Landsat Collection 2 Surface Temperature webpage.

The surface temperature product is provided at 30 m spatial sampling, however, the thermal sensors vary in spectral response, sensitivity and resolution.

Table 11: Landsat thermal sensors specification.

Satellite

Sensor

Spetral Band

Wavelength (µm)

Spatial Resolution (m)

Landsat 8

Thermal Infrared Sensor (TIRS)

10

10.60 - 11.19

100

11

11.50 - 12.51

100

Landsat 7

Enhanced Thematic Mapper Plus (ETM+)

6

10.31 - 12.36

60

Landsat 5

Thematic Mapper (TM)

6

10.40 - 12.50

120

The Level-2 product provides a number of intermediate and quality bands for surface temperature measurement. These bands may help interpret the results.

Table 12: Surface temperature relevant bands.

Name

Explanation

Surface temperature (ST)

The temperature of the Earth’s surface in Kelvin (K).

Thermal radiance (ST_TRAD)

The values produced when thermal band reflectance is converted to radiance.

Upwell radiance (ST_URAD)

The amount of electromagnetic radiation reflected upward from the ground’s surface.

Downwellradiance (ST_DRAD)

The thermal energy radiated onto the ground by all objects in a hemisphere surrounding it.

Atmospheric transmittance (ST_ATRAN)

The ratio of the transmitted radiation to the total radiation incident upon the medium (atmosphere).

Emissivity (ST_EMIS)

The ratio of the energy radiated from a material’s surface to that radiated from a blackbody.

Emissivity_stdev (ST_EMSD)

The extent of deviation of the emissivity product. This layer is used along with cloud_distance to create the quality assessment product.

Distance to cloud (ST_CDIST)

The distance, in kilometers, that a pixel is from the nearest cloud pixel. This layer is used along with emissivity_stdev to create the quality assessment product.

Surface temperature uncertainty (ST_QA)

Provides the Surface Temperature product uncertainty using a combination of uncertainty values and distance to cloud values.