Operational Land Imager
{{Short description|Sensing instrument aboard the Landsat 8 satellite orbiting Earth}}
{{Use dmy dates|date=October 2019}}
File:Landsat Data Continuity Mission Operational Land Imager Instrument Design.jpg
File:Thames Estuary and Wind Farms from Space NASA.jpg taken by OLI]]
The Operational Land Imager (OLI) is a remote sensing instrument aboard Landsat 8, built by Ball Aerospace & Technologies. Landsat 8 is the successor to Landsat 7 and was launched on February 11, 2013.{{cite journal |title=Increased potential to monitor water quality in the near-shore environment with Landsat's next-generation satellite |journal=Journal of Applied Remote Sensing |first1=Aaron D. |last1=Gerace |first2=John R. |last2=Schott |first3=Robert |last3=Nevins |volume=7 |id=073558 |date=January 2013 |page=073558 |doi=10.1117/1.JRS.7.073558 |bibcode=2013JARS....7.3558G|doi-access= }}
OLI is a push broom scanner that uses a four-mirror telescope with fixed mirrors.
Overview and mission
OLI operates alongside TIRS (Thermal Infrared Sensor) on board the LDCM.{{cite web |url=https://lta.cr.usgs.gov/L8 |title=Landsat 8 OLI (Operational Land Imager) and TIRS (Thermal Infrared Sensor) |series=Long Term Archive |publisher=U.S. Geological Survey |access-date=22 March 2018}} The build and design of OLI differs from previous generations of instruments, while still maintaining data continuity with archived Landsat data from the last 40 years by keeping the same spectral and spatial resolutions of previous instruments.
OLI aids the Landsat-8 mission in the imaging of Earth's surface and the collection of moderate resolution data that is used to monitor changing trends on the surface and evaluate how land usage changes over time. The images and data that OLI has helped collect have practical applications today in agriculture, mapping, and monitoring changes in snow, ice, and water.{{cite journal |title=Landsat-8 Operational Land Imager Design, Characterization and Performance |journal=Remote Sensing |first1=Edward J. |last1=Knight |first2=Geir |last2=Kvaran |volume=6 |issue=11 |pages=10286–10305 |date=October 2014 |doi=10.3390/rs61110286 |bibcode=2014RemS....610286K|doi-access=free }}
Specifications and design
OLI is a pushbroom sensor that operates in the visible (VIS) and short wave infrared (SWIR) spectral regions.{{cite web |url=https://landsat.usgs.gov/sites/default/files/documents/Murphy_Morris_Science_Team_OLI_chart.pdf |title=Operational Land Imager |publisher=U.S. Geological Survey |first=Jeanine |last=Murphy-Morris |date=8 January 2008 |access-date=22 March 2018 |archive-date=1 January 2017 |archive-url=https://web.archive.org/web/20170101002332/https://landsat.usgs.gov/sites/default/files/documents/Murphy_Morris_Science_Team_OLI_chart.pdf |url-status=dead }} It has a swath width of {{convert|185|km|mi|adj=on|sp=us}}, which means it can image the entire Earth over a repeating cycle of 16 days.{{Cite web |url=http://www.ball.com/aerospace/programs/oli |title=Operational Land Imager |publisher=Ball Aerospace |access-date=22 March 2018}} The OLI has nine spectral bands, including a panchromatic band:
| class="wikitable"
|+ OLI Spectral Bands{{cite web|last=USGS|title=Landsat 8 U.S. Geological Survey |url=https://www.usgs.gov/landsat-missions/landsat-8}} {{PD-notice}} | |||
| Spectral Band | Description | Wavelength | Resolution |
|---|---|---|---|
| Band 1 | Coastal Aerosol | 0.43 - 0.45 μm | 30 m |
| Band 2 | Blue | 0.450 - 0.51 μm | 30 m |
| Band 3 | Green | 0.53 - 0.59 μm | 30 m |
| Band 4 | Red | 0.64 - 0.67 μm | 30 m |
| Band 5 | Near-Infrared | 0.85 - 0.88 μm | 30 m |
| Band 6 | SWIR 1 | 1.57 - 1.65 μm | 30 m |
| Band 7 | SWIR 2 | 2.11 - 2.29 μm | 30 m |
| Band 8 | Panchromatic (PAN) | 0.50 - 0.68 μm | 15 m |
| Band 9 | Cirrus | 1.36 - 1.38 μm | 30 m |
While the spectral and spatial resolution of OLI's channels were kept the same as prior instruments in order to maintain data continuity with the entire Landsat archive, two spectral bands (the first a blue visible channel and the second an infrared channel) were added. These bands were designated as band 1 and band 9, and serve as an enhancement from previous instruments, which lacked these channels. Band 1 was created to locate and determine water resources and investigate coastal areas, and band 9 serves a unique purpose of detecting cirrus clouds.
Applications
OLI has several different applications due to the many different bands. Band 1 is helpful in imaging shallow water resources and tracking aerosols. Bands 2, 3, and 4 are in the visible spectrum and are helpful in creating true color composite images. Band 5 is helpful for ecology purposes and can help determine vegetation index or NDVI. Bands 6 and 7 are useful in geology and can help in distinguishing different saturated and unsaturated rocks and soils. Band 8 is helpful in creating images with very high resolution and precision. Band 9 is used for detecting different types of clouds.{{cite web |url=https://landsat.gsfc.nasa.gov/landsat-8/landsat-8-bands/ |title=Landsat 8 Bands |series=Landsat Science |publisher=NASA/GSFC |access-date=22 March 2018}}
References
{{Reflist}}
Further reading
- {{cite conference |url=https://calval.cr.usgs.gov/JACIE_files/JACIE11/Presentations/TuePM/325_Knight_JACIE_11.070.pdf |title=The Operational Land Imager: Overview and Performance |conference=2011 Civil Commercial Imagery Evaluation Workshop. 29–31 March 2011. Boulder, Colorado. |first1=Edward J. |last1=Knight |first2=Brent |last2=Canova |first3=Eric |last3=Donley |first4=Geir |last4=Kvaran |first5=Kenton |last5=Lee |date=2011}}
External links
- [http://www.ball.com/aerospace/programs/oli Operational Land Imager] at Ball.com
- [https://landsat.gsfc.nasa.gov/operational-land-imager-oli/ Operational Land Imager] at NASA.gov