Landsat Missions

Memory Effect

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Known Issues

Landsat data are systematic, geometric, radiometric, and terrain corrected to provide the highest quality data to the user communities. Occasionally, anomalies occur and artifacts are discovered that require research and monitoring. The Landsat Calibration and Validation (Cal/Val) team investigates and tracks anomalous data.

A number of known issues regarding Landsat data are listed on this page. Updates to this list are not only made when new anomalies and artifacts are discovered, but also when investigations require changes to already existing issues.

If you discover data artifacts that are not listed here, please contact us.

Known Issues Home, Banding, Coherent Noise, Coherent Noise Storm, Data Loss, Detector Failure, Detector Ringing, Detector Striping, Gimbaled X-band Antenna (GXA) Anomaly, IC Intrusion, Impulse Noise (IN), Lower Truncation Acquisitions, Memory Effect (ME), Optical Leak, Oversaturation, Scan Correlated Shift (SCS), Scan Mirror Pulse, Shutter Synchronization Anomalies, Single Event Upset (SEU)

Memory Effect

Example of Memory Effect in Landsat 5 TM Band 3.

Figure 1. Example of Memory Effect in Landsat 5 Thematic Mapper (TM) Band 3.

Memory Effect (ME) is an artifact that has existed since the early days of optical systems and has been called "Bright Target Recovery" and "Detector Blindness". It manifests as alternating light and dark bands that are most visible near sharp boundaries between bright and dark terrain. Clouds, shorelines, and ice or snow are common terrain features that cause ME. The calibration lamps also cause ME, creating a banding pattern that has no apparent source in the imagery. The pattern slowly disappears as the detectors recover and return to normal operation. Thus, unlike banding and Scan Correlated Shift (SCS), ME changes in magnitude across a scan.

ME is characterized by magnitude and time constant, which is a measure of the length of the artifact. If both of these values are known, ME is correctable. Most modern processing systems correct ME by default; thus, it usually appears only in Level-0 data or in data processed by older systems.

Landsat 4 and 5 TMs have ME in several bands, with a time constant of approximately 1,100 pixels. ME has never been detected in reflective band Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) data, but insignificant amounts may exist in the ETM+ thermal band. It exists in most Multispectral Scanner (MSS) data.

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Landsat represents the world's longest continuously acquired collection of space-based moderate-resolution land remote sensing data. Four decades of imagery provides a unique resource for those who work in agriculture, geology, forestry, regional planning, education, mapping, and global change research. Landsat images are also invaluable for emergency response and disaster relief.

 

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Page Last Modified: 03/28/18 05:02 pm
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