Summary of current radiometric calibration coefficients for Landsat MSS, TM, ETM+, and EO-1 ALI sensors

Summary of current radiometric calibration coefficients for Landsat MSS, TM, ETM+, and EO-1 ALI sensors

GyaneshChandera   Brian L.MarkhambDennis L.Helderc

a SGT, Inc.1 contractor to the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center, Sioux Falls, SD 57198-0001, USA

b National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC), Greenbelt, MD 20771, USA

c  South Dakota State University (SDSU), Brookings, SD 57007, USA

2009 

Abstract 

   This paper provides a summary of the current equations and rescaling factors for converting calibrated Digital Numbers (DNs) to absolute units of at-sensor spectral radiance, Top-OfAtmosphere (TOA) reflectance, and at-sensor brightness temperature. It tabulates the necessary constants for the Multispectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Advanced Land Imager (ALI) sensors. These conversions provide a basis for standardized comparison of data in a single scene or between images acquired on different dates or by different sensors. This paper forms a needed guide for Landsat data users who now have access to the entire Landsat archive at no cost.

Keywords: Landsat, MSS, TM, ETM+, EO-1 ALI, LMIN,,, LMAX A , ESUNA , LPGS, NLAPS, Gain, Bias, Calibration, Spectral Radiance, Reflectance, Temperature

1. Introduction 

  The Landsat series of satellites provides the longest continuous record of satellite-based observations. As such, Landsat is an invaluable resource for monitoring global change and is a primary source of medium spatial resolution Earth observations used in decision-making (Fuller et al., 1994; Townshend et al., 1995; Goward et al., 1997; Vogelmann et al., 2001; Woodcock et al., 2001; Cohen et al., 2004; Goward et al., 2006; Masek et al., 2008; Wulder et al., 2008). To meet observation requirements at a scale revealing both natural and human-induced landscape changes, Landsat provides the only inventory of the global land surface over time on a seasonal basis (Special issues on Landsat, 1984; 1985; 1997; 2001; 2003; 2004; 2006). The Landsat Program began in early 1972 with the launch of the first satellite in the series. As technological capabilities increased, so did the amount and quality of image data captured by the various sensors onboard the satellites. Table 1 presents general information about each Landsat satellite.

   Landsat satellites can be classified into three groups, based on sensor and platform characteristics. The first group consists of Landsat 1 (1-1), Landsat 2 (1-2), and Landsat 3 (1-3), with the Multispectral Scanner (MSS) sensor and the Return Beam Vidicon (RBV) camera as payloads on a "NIMBUS-like" platform. The spatial resolution of the MSS sensor was approximately 79 m (but often processed to pixel size of 60 m), with four bands ranging from the visible blue to the Near-Infrared (NIR) wavelengths. The MSS sensor on L3 included a fifth band in the thermal infrared wavelength, with a spectral range from 10.4 to 12.6 lam. The L1—L3 MSS sensors used a band-naming convention of MSS-4, MSS-5, MSS-6, and MSS-7 for the blue, green, red, and NIR bands, respectively (Markham & Barker, 1983). This designation is obsolete, and to be consistent with the TM and ETM+ sensors, the MSS bands are referred to here as Bands 1-4, respectively. 

  The second group includes Landsat 4 (1-4) and Landsat 5 (1-5), which carry the Thematic Mapper (TM) sensor, as well as the MSS, on the Multimission Modular Spacecraft. This second generation of Landsat satellites marked a significant advance in remote sensing through the addition of a more sophisticated sensor, improved acquisition and transmission of data, and more rapid data processing at a highly automated processing facility. The MSS sensor was included to provide continuity with the earlier Landsat missions, but TM data quickly became the primary source of information used from these satellites because the data offered enhanced spatial, spectral, radiometric, and geometric performance over data from the MSS sensor. The TM sensor has a spatial resolution of 30 m for the six reflective bands and 120 m for the thermal band. Because there are no onboard recorders on these sensors, acquisitions are limited to real-time downlink only. 

   The third group consists of Landsat 6 (1-6) and Landsat 7 (1-7), which include the Enhanced Thematic Mapper (ETM) and the Enhanced Thematic Mapper Plus (ETM+) sensors, respectively. No MSS sensors were included on either satellite. Landsat 6 failed on launch. The L7 ETM+ sensor has a spatial resolution of 30 m for the six reflective bands, 60 m for the thermal band, and includes a panchromatic (pan) band with a 15 m resolution. L7 has a 378 gigabit (Gb) Solid State Recorder (SSR) that can hold 42 minutes (approximately 100 scenes) of sensor data and 29 hours of housekeeping telemetry concurrently (L7 Science Data User's Handbook').

   The Advanced Land Imager (ALI) onboard the Earth Observer-1 (EO-1) satellite is a technology demonstration that serves as a prototype for the Landsat Data Continuity Mission (LDCM). The ALI observes the Earth in 10 spectral bands; nine spectral bands have a spatial resolution of 30 m, and a pan band has a spatial resolution of 10 m.

  The Landsat data archive at the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center holds an unequaled 36-year record of the Earth's surface and is available at no cost to users via the Internet (Woodcock et al., 2008). Users can access and search the Landsat data archive via the Earth Explorer (EE)2 or Global Visualization Viewer (GloVis)3 web sites. Note that the Landsat scenes collected by locations within the International Ground Station (IGS) network may be available only from the particular station that collected the scene. 

7. Conclusion 

   This paper provides equations and rescaling factors for converting Landsat calibrated DNS to absolute units of at-sensor spectral radiance, TOA reflectance, and at-sensor brightness temperature. It tabulates the necessary constants for the MSS, TM, ETM+, and ALI sensors in a coherent manner using the same units and definitions. This paper forms a needed guide for Landsat data users who now have access to the entire Landsat archive at no cost. Studies are ongoing to evaluate the MSS calibration consistency and provide post-calibration adjustments of the MSS sensors so they are consistent over time and consistent between sensors. Further updates to improve the TM and ETM+ thermal band calibration are being investigated, as is the calibration of the L4 TM. 

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