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Instrument Differences

MODIS and VIIRS Instruments

Although quite similar in their design and capabilities there are significant differences between the two sensors that can and do result in differences in their products.

Table 1. MODIS and VIIRS instrument design parameters
Instrument MODIS (Aqua) VIIRS
Orbital Altitude 705 Km 824 Km
Equatorial Crossing Time 13:30 Local Time 13:30 Local Time
Measurement Swath Width 2330 Km 3040 Km
Nadir Pixel Size (primary retrieval band) 1.0 Km 0.75 Km
Swath Edge Pixel Size 2 Km 1.5 Km
Spectral Bands Used for Retrieval

0.44, 0.55, 0.65, 0.86

1.24, 1.38, 1.63 and 2.11 microns

0.49, 0.55, 0.67, 0.86

1.24, 1.38, 1.61 and 2.25 microns


The picture below shows a comparison of a one day global retrieval of MODIS and VIIRS.

Figure 1. One day global retrieval true color image from MODIS (A) and VIIRS (B).  Note that MODIS has gaps near the equator.  VIIRS has a wider swath width which eliminates these gaps.

The table below summarizes some of the product differences between MODIS and VIIRS some of which are consequences of the different sensor capabilities and orbit. Other differences have to do with product creation choices and/or algorithm changes. These will be explained in more detail in the rest of the guide.

Table 2. MODIS and VIIRS Level 2 Aerosol Product Comparison
Sensor MODIS (Aqua) VIIRS
Nadir Product Size 10 x 10 Km 6 x 6 Km
Number of pixels aggregated for product 100 1 Km pixels 64 0.75 Km pixels
Granule Size 5 Minutes; 203 x 135 pixels 6 minutes; 404 x 400 pixels
File Format HDF4 netCDF-4


Figure 2.  Product Sizes:  At left: MODIS 10×10 km level 2 pixel retrieved from 1×1 km level 1b pixels, compared to the size of the VIIRS level 2 product size in lighter blue. At right: VIIRS 6×6km product retrieved from 0.75×0.75 km level 1b pixels.