VIIRS
Visible Infrared Imaging Radiometer Suite. A sensor aboard the Suomi NPP and NOAA-20 satellites, succeeding MODIS. Provides global coverage with 22 spectral bands, used for monitoring vegetation, sea surface temperature, nighttime lights, and active fires.
Overview
The Visible Infrared Imaging Radiometer Suite (VIIRS) is aboard Suomi NPP, NOAA-20, and NOAA-21, operated jointly by NASA and NOAA. Designed as successor to both MODIS and AVHRR, VIIRS provides 22 spectral bands at 375 m and 750 m resolution with a 3,060 km swath for daily global coverage. Its unique Day-Night Band (DNB) detects extremely low visible light levels, enabling observation of city lights, gas flares, and fires at night.
How It Works
VIIRS uses a rotating telescope scanning a 112.56-degree field of view, producing 16 M-bands (750 m), 5 I-bands (375 m), and one Day-Night Band (750 m). A critical improvement over MODIS is pixel aggregation — grouping detectors differently at different scan angles to limit edge-of-swath pixel growth to ~1.6× nadir size (MODIS pixels expand much more). The DNB uses three gain stages spanning seven orders of magnitude, detecting radiances from full daylight down to quarter-moon illumination.
Key Facts
- 22 bands: 16 M-bands (750 m), 5 I-bands (375 m), 1 Day-Night Band (750 m).
- Day-Night Band detects radiance across seven orders of magnitude — full daylight to quarter-moon.
- 3,060 km swath for complete daily global coverage.
- Flying on three satellites: Suomi NPP (2011), NOAA-20 (2017), NOAA-21 (2022).
- Pixel aggregation limits edge-of-swath growth to ~1.6× nadir — major improvement over MODIS.
- Designated successor to MODIS for long-term climate record continuity.
Applications
Nighttime Light Analysis
DNB maps artificial light emissions globally — a proxy for urbanization, economic activity, and energy consumption. Annual composites support socioeconomic research and disaster impact assessment.
Active Fire Detection
The 375 m I-band fire product (VNP14IMG) detects fires with improved sensitivity over MODIS, especially smaller fires at night. Near-real-time delivery supports fire management.
Sea Surface Temperature
Thermal bands provide SST retrievals for weather forecasting, ocean monitoring, fisheries, and coral bleaching early warning.
Vegetation Monitoring
VIIRS vegetation index products continue the MODIS NDVI/EVI time series with improved spatial consistency across the swath.
Limitations & Considerations
375–750 m resolution still too coarse for field-level analysis. 22 bands (vs MODIS 36) means some specialized atmospheric and ocean measurements have reduced coverage. Cross-calibrating with MODIS requires careful attention to spectral response differences. DNB processing must account for stray light, moonlight variation, and atmospheric scattering. Some MODIS ocean color channels lack direct VIIRS equivalents.
History & Background
Developed by Raytheon as part of NPOESS, restructured into JPSS in 2010. First VIIRS launched on Suomi NPP (October 28, 2011). NOAA-20 followed November 18, 2017; NOAA-21 on November 10, 2022. DNB traces lineage to DMSP-OLS nighttime imagery from the 1970s. VIIRS nighttime data has become the global standard for mapping light emissions. Future JPSS missions will extend the record through the 2030s.
Related Terms
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