Landsat-7 ETM+ on-orbit reflective-band radiometric characterization

TLDR: The Landsat-7 Enhanced Thematic Mapper Plus (ETM+) has been and continues to be radiometrically characterized using the Image Assessment System (IAS), a component of the Lands at-7 Ground System, and key radiometric properties analyzed include: overall, coherent, and impulse noise; bias stability; relative gain stability; and other artifacts.

Abstract: The Landsat-7 Enhanced Thematic Mapper Plus (ETM+) has been and continues to be radiometrically characterized using the Image Assessment System (IAS), a component of the Landsat-7 Ground System Key radiometric properties analyzed include: overall, coherent, and impulse noise; bias stability; relative gain stability; and other artifacts The overall instrument noise is characterized across the dynamic range of the instrument during solar diffuser deployments Less than 1% per year increases are observed in signal-independent (dark) noise levels, while signal-dependent noise is stable with time Several coherent noise sources exist in ETM+ data with scene-averaged magnitudes of up to 04 DN, and a noise component at 20 kHz whose magnitude varies across the scan and peaks at the image edges Bit-flip noise does not exist on the ETM+ However, impulse noise due to charged particle hits on the detector array has been discovered The instrument bias is measured every scan line using a shutter Most bands show less than 01 DN variations in bias across the instrument lifetime The panchromatic band is the exception, where the variation approaches 2 DN and is related primarily to temperature The relative gains of the detectors, ie, each detector's gain relative to the band average gain, have been stable to /spl plusmn/01% over the mission life Two exceptions to this stability include band 2 detector 2, which dropped about 1% in gain about 35 years after launch and stabilized, and band 7 detector 5, which has changed several tenths of a percent several times since launch Memory effect and scan-correlated shift, a hysteresis and a random change in bias between multiple states, respectively, both of which have been observed in previous Thematic Mapper sensors, have not been convincingly found in ETM+ data Two artifacts, detector ringing and "oversaturation", affect a small amount of ETM+ data