Landsat Science Products

Landsat Provisional Aquatic Reflectance

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Example of the Landsat 8 Aquatic Reflectance Science Product

Left: Land surface reflectance natural color composite image (bands 4,3,2); Right: aquatic reflectance Band 2 (Blue band) image of San Francisco Bay, using data acquired by Landsat 8 (Path 44 Row 33) on October 7, 2018

Landsat 8 Provisional Aquatic Reflectance is a provisional science product with the potential to make contributions to aquatic science and environmental monitoring capabilities for aquatic ecosystems, especially in coastal environments and inland water bodies.

Landsat’s medium spatial resolution provides the capability to map optically active components of upper water column in inland and near-shore waters. Ocean color, defined as the spectral distribution of reflected visible solar radiation upwelling from beneath the water surface, has revolutionized the field of aquatic remote sensing research. The applications of ocean color remote sensing are extensive and fundamental to understanding and monitoring both marine and freshwater ecosystems.

The Landsat 8 Provisional Aquatic Reflectance product is derived from Landsat 8 Level-1 (L1) reflective bands over water bodies. Top of Atmosphere (TOA) reflectance and auxiliary atmospheric data are input to an atmospheric correction algorithm to retrieve the water-leaving radiance at visible wavelengths. The water-leaving radiances are then normalized by downwelling solar irradiance to remove the remaining effects of solar orientation and atmospheric attenuation to produce spectral remote sensing reflectance (Rrs) for visible bands. Finally, the Rrs visible bands are normalized by the Bidirectional Reflectance Distribution Function (BRDF) of a perfectly reflecting Lambertian surface (multiplied by π) to produce dimensionless Aquatic Reflectance. The atmospheric correction algorithm used to generate Landsat 8 Provisional Aquatic Reflectance products is based on the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) Data Analysis System (SeaDAS) package distributed by NASA’s Ocean Biology Processing Group.

Landsat 8 Provisional Aquatic Reflectance products are generated at 30-meter spatial resolution. The default projection system for Landsat science products is Universal Transverse Mercator (UTM), but other projection systems such as Albers Equal Area (AEA), Sinusoidal, Geographic, and Polar Stereographic (PS) are available through the ESPA on-demand interface as a customized service.

Note: These data are provisional and are subject to revision. They are being provided to meet the need for timely best science. The data have not received final approval by the U.S. Geological Survey (USGS) and are provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the data.

Product Availability

The Landsat 8 Provisional Aquatic Reflectance Science Product is currently available from April 2013 to present for Landsat 8 Operational Land Imager (OLI) data.

Package Content

The Landsat 8 Provisional Aquatic Reflectance product is derived from Landsat 8 Level-1 reflective visible spectral bands over inland water bodies and nearshore coastal regions. The product package includes a metadata file in Extensible Markup Language (.xml) format.

The list below describes the products delivered with the product:

Aquatic Reflectance (AR) – Represents the nondimensional normalized remote sensing reflectance, assuming a Lambertian surface.

Processing Flags (l2_flags) – A bit-packed band that provides per-pixel information about success or failure of processing and validity of sunglint, view angle, solar angle, polarization, and chlorophyll-a for example.

Pixel Quality Assessment (pixel_qa) – The bit combinations that define certain quality conditions. More information about Pixel Quality Assessment can be found in the Land Surface Reflectance Code (LaSRC) Product Guide

Metadata – Includes Landsat scene information in XML and MTL formats.

Auxiliary Data

Surface and atmospheric auxiliary data are required for the successful processing of the Landsat 8 Provisional Aquatic Reflectance Science Product. The auxiliary data include the meteorological data of National Centers for Environmental Prediction (NCEP), ozone data from the Total Ozone Mapping Spectrometer (TOMS) (1978 – 2004) or Aura Ozone Monitoring Instrument (OMI) (2004 – present), and sea ice extent data from the National Snow and Ice Data Center (NSIDC). Auxiliary data for Aquatic Reflectance processing are retrieved from the NASA Ocean Biology Processing Group (https://oceandata.sci.gsfc.nasa.gov/). The latency of the auxiliary data for Aquatic Reflectance processing of new Landsat 8 acquisitions is two days.

Caveats and Constraints

  • The current Landsat 8 Provisional Aquatic Reflectance product is considered provisional at this time. The SeaDAS algorithm and subsequent output products from Landsat 8 OLI have not been systematically validated at large spatial scales. Most preliminary validation efforts are conducted using the Ocean Color component data of the Aerosol Robotic Network (AERONET) (Pahlevan et al., 2017; Ilori et al., 2019), representing moderate coastal waters. The performance of the algorithm over highly turbid and eutrophic inland water bodies requires further characterization, validation, and improvements.
  • This product is currently only available for Landsat 8 Operational Land Imager (OLI) data; the capability to process Landsat 7 Enhanced Thematic Mapper Plus (ETM+), Landsat 4-5 Thematic Mapper (TM), and Sentinel-2 Multi-Spectral Instrument (MSI) data to Aquatic Reflectance is planned for future provisional product releases.
  • An across-track non-uniformity artifact may be visible in the Landsat 8 Provisional Aquatic Reflectance Science Product. This non-uniformity is mainly due to slight differences in the viewing geometries of odd and even Focal Plane Modules (FPM) of OLI in along-track direction (Morfitt et al., 2015). In effect, one set of detectors are forward-looking (looking toward the sun) and the others backward-looking (looking away from the sun) as satellite travels in its orbit. This difference in viewing angles results in collecting different reflected radiances from the water surface and ambient aerosols (Pahlevan et al., 2017). The effect is more pronounced toward the eastern portion of the OLI images a) when the solar elevation angle is higher and/or b) under hazy conditions.
  • The algorithm assesses the pixels for the presence of water (see Algorithm Description Document for more information). This procedure may result in omission and commission classification errors. The commission error will trigger Aquatic Reflectance processing for land pixels. The use of the Landsat 8 Provisional Aquatic Reflectance product should be restricted to water pixels only.
  • The product often includes NoData values for water pixels. These NoData pixels are usually due to atmospheric correction failure. The processing flags (l2_flags) band provides useful information about the traceability of SeaDAS Aquatic Reflectance processing.

  • Currently, ozone data is missing for the following dates and Aquatic Reflectance can not be processed for these time periods.

    • March 12-17, 2017

    • December 30-31, 2018

Data Access

Landsat 8 Provisional Aquatic Reflectance products are available through the USGS EROS Center Science Processing Architecture (ESPA) on-demand interface. Additional customization services such as reprojection, spatial subsetting, and pixel resizing are also available via ESPA.

Further information about ESPA’s processing options can be found in the ESPA On-Demand Interface User Guide.

Visit the Landsat Data Access web page for information about bulk download options.  

Documentation

Landsat Provisional Aquatic Reflectance Product Guide

Landsat 8 Provisional Aquatic Reflectance Algorithm Description Document (ADD)

Citation Information

There are no restrictions on the use of Landsat Science Products. It is not a requirement of data use, but the following citation may be used in publication or presentation materials to acknowledge the USGS as a data source and to credit the original research.

Landsat 8 Provisional Aquatic Reflectance product is courtesy of the U.S. Geological Survey.

The Landsat 8 Provisional Aquatic Reflectance product is based directly on work described in:

Franz, B.A., Bailey, S.W., Kuring, N., & Werdell, P.J. (2015). Ocean color measurements with the Operational Land Imager on Landsat-8: implementation and evaluation in SeaDAS. Journal of Applied Remote Sensing, 9(1), 096070. https://doi.org/10.1117/1.JRS.9.096070

Pahlevan, N., Schott, J.R., Franz, B.A., Zibordi, G., Markham, B., Bailey, S., Schaaf, C.B., Ondrusek, M., Greb, S. & Strait, C.M. (2017). Landsat 8 remote sensing reflectance (Rrs) products: Evaluations, intercomparisons, and enhancements. Remote sensing of environment, 190, 289-301. https://doi.org/10.1016/j.rse.2016.12.030

Reprints or citations of papers or oral presentations based on USGS data are welcome to help the USGS stay informed of how data are being used. These can be sent to User Services at custerserv@usgs.gov.

References

Franz, B.A., Bailey, S. W., Kuring, N., & Werdell, P.J. (2015). Ocean color measurements with the Operational Land Imager on Landsat-8: implementation and evaluation in SeaDAS. Journal of Applied Remote Sensing, 9(1), 096070. https://doi.org/10.1117/1.JRS.9.096070

Gordon, H.R., & Wang, M. (1994). Retrieval of water-leaving radiance and aerosol optical thickness over the oceans with SeaWiFS: a preliminary algorithm. Applied optics, 33(3), 443-452. https://doi.org/10.1364/AO.33.000443

Ilori, C.O., Pahlevan, N., & Knudby, A. (2019). Analyzing Performances of Different Atmospheric Correction Techniques for Landsat 8: Application for Coastal Remote Sensing. Remote Sensing, 11, 469. https://doi.org/10.3390/rs11040469

Mobley, C.D., Werdell, J., Franz, B., Ahmad, Z., & Bailey, S. (2016). Atmospheric correction for satellite ocean color radiometry. NASA Tech. Memo, NASA/TM-2016-217551, p. 85 https://ntrs.nasa.gov/search.jsp?R=20160011399

Morfitt, R., Barsi, J., Levy, R., Markham, B., Micijevic, E., Ong, L., Scaramuzza, P. and Vanderwerff, K. (2015). Landsat-8 Operational Land Imager (OLI) radiometric performance on-orbit. Remote Sensing, 7(2), pp.2208-2237. https://doi.org/10.3390/rs70202208

Pahlevan, N., Schott, J.R., Franz, B.A., Zibordi, G., Markham, B., Bailey, S., Schaaf, C.B., Ondrusek, M., Greb, S. & Strait, C.M. (2017). Landsat 8 remote sensing reflectance (Rrs) products: Evaluations, intercomparisons, and enhancements. Remote sensing of environment, 190, 289-301. https://doi.org/10.1016/j.rse.2016.12.030

Pahlevan, N., & Schott, J.R. (2013). Leveraging EO-1 to evaluate capability of new generation of Landsat sensors for coastal/inland water studies. IEEE Journal of selected topics in applied earth observations and remote sensing, 6(2), 360-374. https://doi.org/10.1109/JSTARS.2012.2235174

 

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