Landsat 8 Thermal Infrared Sensor Geometric Characterization and Calibration

Abstract

Abstract:The Landsat 8 spacecraft was launched on 11 February 2013 carrying two imaging payloads: the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). The TIRS instrument employs a refractive telescope design that is opaque to visible wavelengths making prelaunch geometric characterization challenging. TIRS geometric calibration thus relied heavily on on-orbit measurements. Since the two Landsat 8 payloads are complementary and generate combined Level 1 data products, the TIRS geometric performance requirements emphasize the co-alignment of the OLI and TIRS instrument fields of view and the registration of the OLI reflective bands to the TIRS long-wave infrared emissive bands. The TIRS on-orbit calibration procedures include measuring the TIRS-to-OLI alignment, refining the alignment of the three TIRS sensor chips, and ensuring the alignment of the two TIRS spectral bands. The two key TIRS performance metrics are the OLI reflective to TIRS emissive band registration accuracy, and the registration accuracy between the TIRS thermal bands. The on-orbit calibration campaign conducted during the commissioning period provided an accurate TIRS geometric model that enabled TIRS Level 1 data to meet all geometric accuracy requirements. Seasonal variations in TIRS-to-OLI alignment have led to several small calibration parameter adjustments since commissioning.

The Thermal Infrared Sensor (TIRS) on Landsat 8: Design Overview and Pre-Launch Characterization

“…Table 2 lists the types of calibrations that are being used by TIRS on-orbit. Although some of the calibration parameters have changed a bit from their ground-based values [6,7,8,16,17], TIRS performance has been very stable [17] since its initial turn on in orbit.…”

“…In what follows, only the basic spatial, spectral and noise requirements are discussed. More detail is given in the other papers in this issue [6][7][8].…”

“…The stability requirement, however, was near the limits of measurement capability, and chamber vibrations and ground support equipment effects contributed to the apparent instability. In [7], a detailed description of the geometric performance using both preflight and on-orbit data is presented. There is no measureable on-orbit effect of the temperatureinduced pointing instability measured in ground testing.…”

Landsat-8 Sensor Characterization and Calibration

“…Geometric characterization of the instrument and data both prior to launch and on-orbit are covered in Storey et al [7] for OLI and Storey et al [8] for TIRS. Radiometric performance of the two sensors is covered in a number of papers.…”

Radiometric Calibration Methodology of the Landsat 8 Thermal Infrared Sensor

“…Finally, the gain is applied to convert the adjusted counts into radiance. The radiance data is then geo-located and rectified to the WRS2 grid [12]. The standard Landsat Earth scene images available to users are expressed as 16-bit integer numbers and must be rescaled to spectral radiance using the provided coefficients in the image metadata.…”