A digital color image displayed on a monitor is composed of three different color channels: red, green, and blue. Satellite images are made by combining the reflected light detected by the sensor at various wavelengths (spectral bands) and making them into a single image. Below is a list of the true-color and false-color images that are provided, each tailored to highlight different land surface, atmospheric, and oceanic features.
- Terra, MODIS,Corrected Reflectance, True Color (24 February 2000 - present)
- Terra, MODIS, Corrected Reflectance, 7-2-1 (24 February 2000 - present)
- Terra, MODIS, Corrected Reflectance, 3-6-7 (Temporal coverage: 24 February 2000 - present)
- Aqua, MODIS, Corrected Reflectance, True Color (3 July 2002 - present)
- Aqua, MODIS, Corrected Reflectance, 7-2-1 (3 July 2002 - present)
- Suomi NPP, VIIRS, Corrected Reflectance, True Color (24 November 2015 - present)
- Suomi NPP, VIIRS, Corrected Reflectance, M11-I2-I1 (24 November 2015 - present)
- Suomi NPP, VIIRS, Corrected Reflectance, M3-I3-M11 (24 November 2015 - present)
- Suomi NPP, VIIRS, Black Marble Nighttime At Sensor Radiance (Day/Night Band) (18 November 2020 - present)
- Suomi NPP, VIIRS, Black Marble Nighttime Blue/Yellow Composite (Day/Night Band) (30 April 2021 - present)
- Suomi NPP, VIIRS, Day/Night Band, ENCC (Nighttime imagery) (30 November 2016 - present)
- NOAA-20, VIIRS, Corrected Reflectance, True Color (25 April 2020 - present)
- NOAA-20, VIIRS, Corrected Reflectance, M11-I2-I1 (25 April 2020 - present)
- NOAA-20, VIIRS, Corrected Reflectance, M3-I3-M11 (25 April 2020 - present)
Terra, MODIS, Corrected Reflectance, True Color | Aqua, MODIS, Corrected Reflectance, True Color
True Color: Red = Band 1, Green = Band 4, Blue = Band 3
These images are called true-color or natural color because this combination of wavelengths is similar to what the human eye would see. The images are natural-looking images of land surface, oceanic and atmospheric features. The downside of this set of bands is that they tend to produce a hazy image.
MODIS Corrected Reflectance vs. MODIS Surface Reflectance
The MODIS Corrected Reflectance algorithm utilizes MODIS Level 1B data (the calibrated, geolocated radiances). It is not a standard, science quality product. The purpose of this algorithm is to provide natural-looking images by removing gross atmospheric effects, such as Rayleigh scattering, from MODIS visible bands 1-7. The algorithm was developed by the original MODIS Rapid Response team to address the needs of the fire monitoring community who want to see smoke. Corrected Reflectance shows smoke more clearly than the standard Surface Reflectance product. In contrast, the MODIS Land Surface Reflectance product (MOD09) is a more complete atmospheric correction algorithm that includes aerosol correction, and is designed to derive land surface properties. In clear atmospheric conditions the Corrected Reflectance product is very similar to the MOD09 product, but they depart from each other in presence of aerosols. If you wish to perform a complete atmospheric correction, please do not use the Corrected Reflectance algorithm. An additional difference is that the Land Surface Reflectance product is only tuned for calculating the reflectance over land surfaces.
References: NASA Earthdata—Rapid Response FAQ; AMNH—Biodiversity Informatics, Band Combination; NASA Earthdata—Creating Reprojected True Color MODIS Images: A Tutorial
Terra, MODIS, Corrected Reflectance, 7-2-1 | Aqua, MODIS, Corrected Reflectance, 7-2-1
False-Color: Red = Band 7, Green = Band 2, Blue = Band 1
This combination is most useful for distinguishing burn scars from naturally low vegetation or bare soil and enhancing floods. This combination can also be used to distinguish snow and ice from clouds. Snow and ice are very reflective in the visible part of the spectrum (Band 1), and absorbent in Bands 2 (near infrared) and 7 (short-wave infrared, or SWIR). Thick ice and snow appear vivid sky blue, while small ice crystals in high-level clouds will also appear blueish, and water clouds will appear white.
Vegetation and bare ground
Vegetation is very reflective in the near infrared (Band 2), and absorbent in Band 1 and Band 7. Assigning that band to green means even the smallest hint of vegetation will appear bright green in the image. Naturally bare soil, like a desert, is reflective in all bands used in this image, but more so in the SWIR (Band 7, red) and so soils will often have a pinkish tinge.
Burned areas
Burned areas or fire-affected areas are characterized by deposits of charcoal and ash, removal of vegetation and/or the alteration of vegetation structure. When bare soil becomes exposed, the brightness in Band 1 may increase, but that may be offset by the presence of black carbon residue; the near infrared (Band 2) will become darker, and Band 7 becomes more reflective. When assigned to red in the image, Band 7 will show burn scars as deep or bright red, depending on the type of vegetation burned, the amount of residue, or the completeness of the burn.
Water
Liquid water on the ground appears very dark since it absorbs in the red and the SWIR. Sediments in water appear dark blue. Ice and snow appear as bright turquoise. Clouds comprised of small water droplets scatter light equally in both the visible and the SWIR and will appear white. These clouds are usually lower to the ground and warmer. High and cold clouds are comprised of ice crystals and will appear turquoise.
Terra, MODIS, Corrected Reflectance, 3-6-7
False-Color: Red = Band 3, Green = Band 6, Blue = Band 7
This combination is used to map snow and ice. Snow and ice are very reflective in the visible part of the spectrum (Band 3), and very absorbent in Bands 6 and 7 (short-wave infrared, or SWIR). This band combination is good for distinguishing liquid water from frozen water, for example, clouds over snow, ice cloud versus water cloud; or floods from dense vegetation. This band combination is only available for MODIS (Terra) because 70% of the band 6 sensors on the MODIS instrument on NASA's Aqua satellite failed shortly after launch.
Snow and Ice
Since the only visible light used in these images (Band 3) is assigned to red, snow and ice appear bright red. The more ice, the stronger the absorption in the SWIR bands, and the more red the color. Thick ice and snow appear vivid red (or red-orange), while small ice crystals in high-level clouds will appear reddish-orange or peach.
Vegetation
Vegetation will appear green in this band combination, as vegetation is absorbent in Bands 3 and 7, but reflective in Band 6. Bare soil and deserts will appear bright cyan in the image since it much more reflective in Band 6 and 7 than Band 3.
Water
Liquid water on the ground will appear very dark since it absorbs in the red and the SWIR, but small liquid water drops in clouds scatter light equally in both the visible and the SWIR, and will therefore appear white. Sediments in water appear dark red.
Suomi NPP, VIIRS, Corrected Reflectance, True Color | NOAA-20, VIIRS, Corrected Reflectance, True Color
True Color: Red = Band I1, Green = Band M4, Blue = Band M3
These images are called true-color or natural color because this combination of wavelengths is similar to what the human eye would see. The images are natural-looking images of land surface, oceanic and atmospheric features.
Suomi NPP, VIIRS, Corrected Reflectance, M11-I2-I1 | NOAA-20, VIIRS, Corrected Reflectance, M11-I2-I1
False-Color: Red = M11, Green = I2, Blue = I1
This combination is most useful for distinguishing burn scars from naturally low vegetation or bare soil and enhancing floods. This combination can also be used to distinguish snow and ice from clouds. Snow and ice are very reflective in the visible part of the spectrum (Band I1), and absorbent in Bands I2 (near infrared) and M11 (short-wave infrared, or SWIR). Thick ice and snow appear vivid sky blue, while small ice crystals in high-level clouds will also appear blueish, and water clouds will appear white. The VIIRS instrument in aboard the joint NASA/NOAA Suomi NPP satellite.
Vegetation and bare ground
Vegetation is very reflective in the near infrared (Band I2), and absorbent in Band I1 and Band M11. Assigning that band to green means even the smallest hint of vegetation will appear bright green in the image. Naturally bare soil, like a desert, is reflective in all bands used in this image, but more so in the SWIR (Band M11, red) and so soils will often have a pinkish tinge.
Burned areas
Burned areas or fire-affected areas are characterized by deposits of charcoal and ash, removal of vegetation and/or the alteration of vegetation structure. When bare soil becomes exposed, the brightness in Band I1 may increase, but that may be offset by the presence of black carbon residue; the near infrared (Band I2) will become darker, and Band M11 becomes more reflective. When assigned to red in the image, Band M11 will show burn scars as deep or bright red, depending on the type of vegetation burned, the amount of residue, or the completeness of the burn.
Water
Liquid water on the ground appears very dark since it absorbs in the red and the SWIR. Sediments in water appear dark blue. Ice and snow appear as bright turquoise. Clouds comprised of small water droplets scatter light equally in both the visible and the SWIR and will appear white. These clouds are usually lower to the ground and warmer. High and cold clouds are comprised of ice crystals and will appear turquoise.
References: Earthdata: VIIRS
Suomi NPP, VIIRS, Corrected Reflectance, M3-I3-M11 | NOAA-20, VIIRS, Corrected Reflectance, M3-I3-M11
False-Color: Red = M3, Green = I3, Blue = M11
This combination is used to map snow and ice. Snow and ice are very reflective in the visible part of the spectrum (Band M3), and very absorbent in Bands I3 and M11 (short-wave infrared, or SWIR). This band combination is good for distinguishing liquid water from frozen water, for example, clouds over snow, ice cloud versus water cloud; or floods from dense vegetation. The VIIRS instrument in aboard the joint NASA/NOAA Suomi NPP satellite.
Snow and Ice
Since the only visible light used in these images (Band M3) is assigned to red, snow and ice appear bright red. The more ice, the stronger the absorption in the SWIR bands, and the more red the color. Thick ice and snow appear vivid red (or dark pink), while small ice crystals in high-level clouds will appear pinkish.
Vegetation
Vegetation will appear green in this band combination, as vegetation is absorbent in Bands M3 and M11, but reflective in Band I3. Bare soil and deserts will appear bright cyan in the image since it much more reflective in Band I3 and M11 than Band M3.
Water
Liquid water on the ground will appear very dark since it absorbs in the red and the SWIR, but small liquid water drops in clouds scatter light equally in both the visible and the SWIR, and will therefore appear white. Sediments in water appear dark red.
References: Earthdata: VIIRS
Suomi NPP, VIIRS, Black Marble Nighttime At Sensor Radiance (Day/Night Band)
The Black Marble Nighttime At Sensor Radiance (Day/Night Band) layer is created from NASA’s Black Marble daily at-sensor top-of-atmosphere nighttime radiance product (VNP46A1). It is displayed as a grayscale image. The layer is expressed in radiance units (nW/(cm2 sr)) with log10 conversion. It is stretched up to 38 nW/(cm2 sr) resulting in improvements in capturing city lights in greater spatial detail than traditional Nighttime Imagery resampled at 0-255 (e.g., Day/Night Band, Enhanced Near Constant Contrast).
The ultra-sensitivity of the VIIRS Day/Night Band enables scientists to capture the Earth’s surface and atmosphere in low light conditions, allowing for better monitoring of nighttime phenomena. These images are also useful for assessing anthropogenic sources of light emissions under varying illumination conditions. For instance, during partial to full moon conditions, the layer can identify the location and features of clouds and other natural terrestrial features such as sea ice and snow cover, while enabling temporal observations in urban regions, regardless of moonlit conditions. As such, the layer is particularly useful for detecting city lights, lightning, auroras, fires, gas flares, and fishing fleets.
The Black Marble Nighttime At Sensor Radiance (Day/Night Band) layer is available in near real-time from the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the joint NASA/NOAA Suomi National Polar orbiting Partnership (Suomi NPP) satellite. The sensor resolution is 750 m at nadir, imagery resolution is 500 m, and the temporal resolution is daily.
Dataset doi:10.5067/VIIRS/VNP46A1.001
References: VNP46A1; Black Marble User Guide; Black Marble ATBD; The Lights of London. NASA Earth Observatory; Out of the Blue and Into the Black. NASA Earth Observatory.
Román, M. O., Z. Wang, Q. Sun, V. Kalb, S. D. Miller, A. Molthan, L. Schultz, J. Bell, E. C. Stokes, B. Pandey, K. C. Seto, D. Hall, T. Oda, R. E. Wolfe, G. Lin, N. Golpayegani, S. Devadiga, C. Davidson, S. Sarkar, C. Praderas, J. Schmaltz, R. Boller, J. Stevens, O. M. Ramos Gonzalez, E. Padilla, J. Alonso, Y. Detrés, R. Armstrong, I. Miranda, Y. Conte, N. Marrero, K. MacManus, T. Esch, and E. J. Masuoka. 2018. "NASA’s Black Marble nighttime lights product suite." Remote Sensing of Environment 210 113-143 doi:10.1016/j.rse.2018.03.017
Lee, T., S. Miller, F. Turk, C. Schueler, R. Julian, S. Deyo, P. Dills, and S. Wang, 2006: The NPOESS VIIRS Day/Night Visible Sensor. Bull. Amer. Meteor. Soc., 87, 191–199, doi: 10.1175/BAMS-87-2-191
Román, M. O. and Stokes, E. C. (2015), Holidays in lights: Tracking cultural patterns in demand for energy services. Earth's Future, 3: 182–205. doi:10.1002/2014EF000285
Suomi NPP, VIIRS, Black Marble Nighttime Blue/Yellow Composite (Day/Night Band)
The Black Marble Nighttime Blue/Yellow Composite (Day/Night Band) is a false color composite using the VIIRS at-sensor radiance and the brightness temperatures from the M15 band. Data are provided by NASA’s VNP46A1 product using Suomi NPP observations. Originally designed by the Naval Research Lab and incorporated into NASA research and applications efforts, the resulting false color scheme produces nighttime city lights in shades of yellow with infrared, nighttime cloud presence in shades of blue. During bright moonlight conditions, moonlight reflected from cloud tops and the land surface may also provide a yellow hue to those features. Comparisons of cloud-free conditions before and after a period of significant change, such as new city growth, disasters, fires, or other factors, may exhibit a change in emitted light (yellows) from those features over time.
The Black Marble Nighttime Blue/Yellow Composite (Day/Night Band) layer is available in near real-time from the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the joint NASA/NOAA Suomi National Polar orbiting Partnership (Suomi NPP) satellite. The sensor resolution is 750 m at nadir, imagery resolution is 500 m, and the temporal resolution is daily.
Dataset doi:10.5067/VIIRS/VNP46A1.001
References: VNP46A1; Black Marble User Guide; Black Marble ATBD; The Lights of London. NASA Earth Observatory; Out of the Blue and Into the Black. NASA Earth Observatory.
Román, M. O., Z. Wang, Q. Sun, V. Kalb, S. D. Miller, A. Molthan, L. Schultz, J. Bell, E. C. Stokes, B. Pandey, K. C. Seto, D. Hall, T. Oda, R. E. Wolfe, G. Lin, N. Golpayegani, S. Devadiga, C. Davidson, S. Sarkar, C. Praderas, J. Schmaltz, R. Boller, J. Stevens, O. M. Ramos Gonzalez, E. Padilla, J. Alonso, Y. Detrés, R. Armstrong, I. Miranda, Y. Conte, N. Marrero, K. MacManus, T. Esch, and E. J. Masuoka. 2018. "NASA’s Black Marble nighttime lights product suite." Remote Sensing of Environment 210 113-143 doi:10.1016/j.rse.2018.03.017
Lee, T., S. Miller, F. Turk, C. Schueler, R. Julian, S. Deyo, P. Dills, and S. Wang, 2006: The NPOESS VIIRS Day/Night Visible Sensor. Bull. Amer. Meteor. Soc., 87, 191–199, doi: 10.1175/BAMS-87-2-191
Román, M. O. and Stokes, E. C. (2015), Holidays in lights: Tracking cultural patterns in demand for energy services. Earth's Future, 3: 182–205. doi:10.1002/2014EF000285
Suomi NPP, VIIRS, Day/Night Band, ENCC (Nighttime imagery)
The VIIRS Nighttime Imagery (Day/Night Band, Enhanced Near Constant Contrast) shows the Earth’s surface and atmosphere using a sensor designed to capture low-light emission sources, under varying illumination conditions. It is displayed as a grayscale image. Sources of illumination include both natural and anthropogenic sources of light emissions. Lunar reflection can be used to highlight the location and features of clouds and other terrestrial features such as sea ice and snow cover when there is partial to full moon conditions. When there is no moonlight, natural and anthropogenic night time light emissions are highlighted such as city lights, lightning, upper-atmospheric gravity waves, auroras, fires, gas flares, and fishing fleets. This layer is useful for displaying cities and highways at night, the tracking of shipping and fishing fleets, as well as fires and the burning of waste natural gas (gas flares) from on and offshore oil/gas production sites.
The Visible Infrared Imaging Radiometer Suite (VIIRS) Nighttime Imagery (Day/Night Band, Enhanced Near Constant Contrast) layer is mainly a qualitative product and should be strictly used for image display purposes. Each VIIRS Level 1B scan (6-minutes in total length) is individually processed and normalized based on a static set of values that predict the viewing and illumination geometries of each pixel. Because of the confounding factors that influence a VIIRS scan from one night to the next (e.g., more/less cloudy days, with more/less moon illumination conditions), individual ENCC pixel-based values are not comparable over time. For accurate time-series detection (e.g., monitoring short-term increases or reductions in artificial lights at night), users are referred to NASA’s Black Marble standard product suite (VNP46A1/VNP46A2 for Suomi NPP). These standard products correct for short-term variations in lunar and environmental conditions. They also provide the necessary quality assurance (QA) flags and additional layers to identify and isolate potential sources of noise and measurement error (e.g., clouds, moon-light, and snow contaminated pixels) and variations (e.g. lunar and view angles and view time) in a statistically robust fashion.
The current ENCC Nighttime Imagery layer is available from the VIIRS instrument aboard the joint NASA/NOAA Suomi National Polar orbiting Partnership (Suomi NPP) satellite at a daily temporal resolution. The VIIRS Day/Night Band (DNB) sensor resolution is 750 m at nadir and the ENCC imagery layer’s gridded resolution is 15 arc-second (approximately 500 meters at the equator).
References: Hillger, D., Seaman, C., Liang, C., Miller, S., Lindsey, D., & Kopp, T. (2014). Suomi NPP VIIRS imagery evaluation. Journal of Geophysical Research: Atmospheres, 119(11), 6440-6455, doi:10.1002/2013JD021170.
Román, M. O., Wang, Z., Sun, Q., Kalb, V., Miller, S. D., Molthan, A., ... & Masuoka, E. J. (2018). NASA's Black Marble nighttime lights product suite. Remote Sensing of Environment, 210, 113-143, doi:10.1016/j.rse.2018.03.017.