Loop of VIIRS Day Night Band Reflectance for Tropical Storm/Hurricane Isaac

As a follow up to Geoffrey’s post yesterday, I’ve revisited our short-term archive of data from the day-night band on the Visible Infrared Imaging Radiometer Suite (VIIRS), carried aboard the Suomi National Polar-Orbiting Partnership.  In the image loop below, cloud features are illuminated by moonlight, and the final image is provided as a reflectance that is normalized based upon the available lunar input.  The resulting image is comparable to visible imagery we see from geostationary satellites — a lot of detail is provided regarding cloud texture (and type), circulation patterns, and other features.  City lights are also illuminated, and also can hint at relatively thin ice clouds as they pass over large metropolitan areas and cause the underlying lights to become diffuse.  After landfall, many of the bright city light sources in the New Orleans area no longer diffuse through the overlying cloud cover — either due to the widespread power outages, where no light is available, or perhaps because despite their relatively thin appearance, cloud cover in the area is thick enough to obscure the city lights below.  As Isaac continues to move out of the area, additional passes from VIIRS can be used to help establish where power outages may have occurred by looking for areas where city lights and lights from other human activities are no longer visible.
By clicking on the image below, an animated GIF highlights the storm’s movement over the past few days.

Animation of recent passes of the VIIRS Day-Night Band featuring coverage of Tropical Storm and Hurricane Isaac. Various cloud features are illuminated by reflected moonlight in addition to city lights across the southeastern United States and along the coast of the Gulf of Mexico.

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