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, Day/Night Band, Black Marble Nighttime At Sensor Radiance (Nighttime Imagery) (18 November 2020 - present)
- Suomi NPP, VIIRS, Day/Night Band, Black Marble Nighttime Blue/Yellow Composite (Nighttime Imagery) (30 April 2021 - present)
- Suomi NPP, VIIRS, Day/Night Band, (Nighttime imagery) (11 March 2012 - present)
- NOAA-20, VIIRS, Corrected Reflectance, True Color (5 January 2018 - present)
- NOAA-20, VIIRS, Corrected Reflectance, M11-I2-I1 (5 January 2018 - present)
- NOAA-20, VIIRS, Corrected Reflectance, M3-I3-M11 (5 January 2018 - present)
- NOAA-20, VIIRS, Day/Night Band, Black Marble Nighttime At Sensor Radiance (Nighttime Imagery) (25 March 2024 - present)
- NOAA-20, VIIRS, Day/Night Band, Black Marble Nighttime Blue/Yellow Composite (Nighttime Imagery) (25 March 2024 - present)
- NOAA-20, VIIRS, Day/Night Band, (Nighttime imagery) (17 February 2018 - present)
- NOAA-21, VIIRS, Corrected Reflectance, True Color (19 April 2024 - present)
- NOAA-21, VIIRS, Corrected Reflectance, M11-I2-I1 (19 April 2024 - present)
- NOAA-21, VIIRS, Corrected Reflectance, M3-I3-M11 (19 April 2024 - present)
- NOAA-21, VIIRS, Day/Night Band, (Nighttime imagery) (19 April 2023 - present)
- PACE, OCI, Corrected Reflectance, True Color (25 February 2024 - present)
MODIS Bands: Red = Band 1, Green = Band 4, Blue = Band 3
VIIRS Bands: 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. The downside of this set of bands is that they tend to produce a hazy image.
References: NASA Earthdata—Creating Reprojected True Color MODIS Images: A Tutorial, NASA Earthdata Forum - LANCE FAQ
Terra, MODIS | Aqua, MODIS | Suomi NPP, VIIRS | NOAA-20, VIIRS | NOAA-21, Corrected Reflectance, 7-2-1
MODIS Bands: Red = Band 7, Green = Band 2, Blue = Band 1
VIIRS Bands: Red = Band M11, Green = Band I2, Blue = Band 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 (MODIS Band 1/VIIRS Band I1), and absorbent in MODIS Band 2/VIIRS Band I2 (near infrared) and MODIS Band 7/VIIRS Band 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.
Vegetation and bare ground
Vegetation is very reflective in the near infrared (MODIS Band 2/VIIRS Band I2), and absorbent in MODIS Band 1/VIIRS Band I1 and MODIS Band 7/VIIRS 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 (MODIS Band 7/VIIRS 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 MODIS Band 1/VIIRS Band I1 may increase, but that may be offset by the presence of black carbon residue; the near infrared (Band 2) will become darker, and MODIS Band 7/VIIRS Band M11 becomes more reflective. When assigned to red in the image, MODIS Band 7/VIIRS 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.
Terra, MODIS | Suomi NPP, VIIRS | NOAA-20, VIIRS | NOAA-21, Corrected Reflectance, 3-6-7
MODIS Bands: Red = Band 3, Green = Band 6, Blue = Band 7
VIIRS Bands: Red = Band M3, Green = Band I3, Blue = Band M11
This combination is used to map snow and ice. Snow and ice are very reflective in the visible part of the spectrum (MODIS Band 3/VIIRS Band M3), and very absorbent in MODIS Band 6/VIIRS Band I3 and MODIS Band 7/VIIRS Band 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. (This band combination is not available for the MODIS instrument on NASA's Aqua satellite, as 70% of the band 6 sensors failed shortly after launch.)
Snow and Ice
Since the only visible light used in these images (MODIS Band 3/VIIRS 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 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 MODIS Band 3/ VIIRS Band M3 and MODIS Band 7/VIIRS Band M11, but reflective in MODIS Band 6/VIIRS Band I3. Bare soil and deserts will appear bright cyan in the image since it is much more reflective in MODIS Band 6/VIIRS Band I3 and MODIS Band 7/VIIRS Band M11 than MODIS Band 3/VIIRS 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.
Suomi NPP, VIIRS | NOAA-20, VIIRS, Day/Night Band, Black Marble Nighttime At Sensor Radiance (Nighttime Imagery)
The Day/Night Band, Black Marble Nighttime At Sensor Radiance layer is created from NASA’s Black Marble daily at-sensor top-of-atmosphere nighttime radiance product (VNP46A1)/(VJ146A1). 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.
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 sensor resolution is 750 m at nadir, imagery resolution is 500 m, and the temporal resolution is daily.
Earthdata - Nighttime Lights; 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 | NOAA-20, VIIRS, Day/Night Band, Black Marble Nighttime Blue/Yellow Composite (Nighttime Imagery)
The Day/Night Band, Black Marble Nighttime Blue/Yellow Composite (Nighttime Imagery) is a false color composite using the VIIRS at-sensor radiance and the brightness temperatures from the M15 band. Data are provided by the VNP46A1 product using Suomi NPP observations/VJ146A1 product using NOAA-20 (JPSS-1) 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 sensor resolution is 750 m at nadir, imagery resolution is 500 m, and the temporal resolution is daily.
Suomi NPP, VIIRS | NOAA-20, VIIRS | NOAA-21, VIIRS, Day/Night Band (Nighttime imagery)
The Nighttime Imagery (Day/Night Band) layer shows regions of the Earth at roughly midnight local time for the selected date. The image is in grayscale. Terrestrial features illuminated by moonlight include clouds, atmospheric gravity waves, sea ice, and snow cover. Other light sources that may be visible are city lights, lightning, auroras, fires, gas flares, and fishing fleets.
The composite image for a day is stitched from ~14 orbits of a sun-synchronous satellite, traveling from north to south (descending) when on the nighttime side of the Earth. For each orbit, image values are scaled against other values in the same orbit so that a histogram of all values in an orbit is approximately uniform. This histogram equalization improves contrast across the large range of values in the image. A side-effect of this process is that the image generally appears overall brightest at the new moon instead of the full moon, as may be expected. For more details, see the documentation for SatPy and Polar2Grid.
Due to the per-orbit scaling, this is a qualitative product intended to be used strictly for image display purposes. Furthermore, pixel values for different dates should not be directly compared, as the scaling is not normalized across time. For a quantitative product that can be compared to itself across different dates, see the "Black Marble Nighttime At Sensor Radiance" layer.
The sensor resolution is 750 m at nadir and the imagery resolution is 1km.