Using RGB images for discrimination of clouds vs snow cover

December 16th, 2015 |

Suomi NPP VIIRS Visible (0.64 µm) and False-color RGB images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and False-color RGB images [click to enlarge]

On the afternoon of 16 December 2015, a toggle between Suomi NPP VIIRS Visible (0.64 µm, 375-m resolution) and False-color Red/Green/Blue (RGB) images (above) showed areas of snow cover (shades of red on the RGB image) that remained from separate snowfall events during the 13 December15 December time period (24-hour snowfall maps). Snow depth on the morning of 16 December was as high as 14 inches in the Foothills of eastern Colorado, 12 inches in both southeastern Wyoming and western Nebraska, and 4 inches in southwestern Kansas.

Comparing the false-color RGB image with the visible image made it easier to unambiguously discriminate between snow cover and supercooled water droplet cloud features (which appear as shades of white on the RGB image). In addition, consecutive VIIRS RGB images (below) showed the areas where snow cover was beginning to melt during the ~102 minutes between overpasses of the Suomi NPP satellite.

Suomi NPP VIIRS False-color RGB images at 1842 and 2025 UTC [click to enlarge]

Suomi NPP VIIRS False-color RGB images at 1842 and 2025 UTC [click to enlarge]

A late-morning overpass of the Landsat-8 satellite provided a 30-meter resolution view (below) of the circular and rectangular irrigated agricultural fields in far southwestern Kansas and parts of the Oklahoma panhandle. In this RGB image (viewed using RealEarth), snow cover appears as cyan; in areas without snow cover, bare ground is brown and vegetation (crops) are green.

Landsat-8 False-color RGB image, with Google maps background [click to enlarge]

Landsat-8 False-color RGB image, with Google maps background [click to enlarge]