This site has moved to www.usgs.gov/landsat
Please visit the new site and update any bookmarks you have. 
 

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), Thermal Infrared Sensor Select Mechanism Anomaly

Coherent Noise Storm

Figure 1. Coherent Noise Storm in Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) Band 1 data at the moment of Scan Line Corrector (SLC) Failure.
Click to view larger image. - .gif (65 KB)

A Coherent Noise Storm is a symptom of a serious, sudden event on the satellite or instrument. As a system onboard the satellite fails, electrical anomalies can create sudden and brief bursts of noise that exhibit coherent frequency.

Only one Coherent Noise Storm has been observed in Landsat imagery, at the moment of failure for the Landat 7 ETM+ Scan Line Corrector (SLC) on May 29, 2003. The scan lines were properly aligned at the top of the image but were misaligned at the bottom (see Figure 1). In the middle of the image, the SLC failed catastrophically. This failure was accompanied by noise of very high magnitude—up to 200 DN—with a frequency of 20 kHz that lasted for about eight scans before disappearing. This noise was observed in most bands but was highest in Bands 1 and 8, where Detector Ringing events had been seen previously.

Coherent Noise Storms are cause for immediate concern. They are signs that a sudden electrical change has occurred onboard the satellite or instrument. Even after the event has passed, detectors involved in the noise storm may exhibit a change in their noise characteristics.