The Suomi National Polar-orbiting Partnership (SNPP) Visible Infra-red Imaging Radiometer Suite (VIIRS) surface reflectance products provide estimates of surface reflectance derived from each of the twelve VIIRS reflective bands. Surface reflectance is derived by adjusting top-of-atmosphere reflectance to compensate for atmospheric effects. The effects of molecular gases, including ozone and water vapor, and atmospheric aerosols are also corrected. The VIIRS Level 1B (L1B) top-of-atmosphere calibrated instrument data, following corrections to address atmospheric gases and aerosols, help produce the Level 2 (L2) product. These L2 inputs help generate additional higher-level gridded products.

VNP09 is the short name for the L2 orbital swath-based atmospherically corrected surface reflectance product generated daily at 375-meter and 750-meter resolutions. VNP09 contains approximately 6 minutes of data yielding 240 granules in a 24-hour cycle.

Spectral Band Coverage

VNP09 offers surface reflectance values for the following resolutions and bands: 

• 375-meter resolution: Image (I) Bands I1, I2, and I3
• 750-meter resolution: Moderate (M) Bands M1-M5, M7, M8, M10, and M11

Algorithm Inputs

The inputs to the surface reflectance algorithm include top-of-atmosphere reflectances derived from the VIIRS I-bands and M-bands, VIIRS Cloud Mask (VNP35_L2), VIIRS Aerosol Optical Thickness (VNP04_L2), Aerosol Model Information (VNPAMI_L2), VIIRS Geolocation (VNP03IMG), and atmospheric data from NCEP (National Centers for Environmental Prediction) reanalysis (surface pressure, atmospheric precipitable water, and ozone concentration). All surface reflectance products are generated under all atmospheric conditions for daytime only; nighttime and ocean observations are excluded. Reflectance values when not produced, are replaced by fill-values in the L2 products and are excluded in the Level 3 (L3) products.

Product Validation and Data Record

The version 2.0 (v2.0) Surface Reflectance products are validated to Stage 3; this means that the uncertainties in this product are well-quantified through comparison with both in situ and other reference data. These uncertainties are characterized in a statistically rigorous manner over multiple global locations and time periods. The spatial and temporal consistency of this product has also been evaluated over a set of globally representative locations and time periods. The v2.0 VNP09 collection’s record starts from January 19, 2012 (2012–019).

Science Data Sets

The L2 VNP09 product, in Network Common Data Form (netCDF4) format, contains the following Science Data Sets (SDS):

1. 375m_Surface_Reflectance_Band_I1
2. 375m_Surface_Reflectance_Band_I2
3. 375m_Surface_Reflectance_Band_I3
4. 750m_Surface_Reflectance_Band_M1
5. 750m_Surface_Reflectance_Band_M2
6. 750m_Surface_Reflectance_Band_M3
7. 750m_Surface_Reflectance_Band_M4
8. 750m_Surface_Reflectance_Band_M5
9. 750m_Surface_Reflectance_Band_M7
10. 750m_Surface_Reflectance_Band_M8
11. 750m_Surface_Reflectance_Band_M10
12. 750m_Surface_Reflectance_Band_M11
13. land_water_mask
14. QF1_Surface_Reflectance
15. QF2_Surface_Reflectance
16. QF3_Surface_Reflectance
17. QF4_Surface_Reflectance
18. QF5_Surface_Reflectance
19. QF6_Surface_Reflectance
20. QF7_Surface_Reflectance