New Orleans Power Outages Seen by the VIIRS Day-Night Band

As the remnants of Isaac continued to move away from Louisiana, reductions in cloud cover allowed for a clearer picture of the New Orleans metropolitan area by the VIIRS Day-Night band.  In the imagery below, we are using the raw radiance values from the instrument (rather than reflectance), combined with an image enhancement technique to help enhance the depiction of city lights in the region.  Cloud cover in the image from August 31 remains illuminated by moonlight.  In the first image, here is New Orleans seen from the day-night band radiance on August 27.  Note the consistent cluster of lights on the south shore of Lake Pontchartrain consistent with the New Orleans urban area.  There are also clusters of light along major interstates.  In the second image, there is substantial cloud cover over much of Louisiana, including active thunderstorms in the eastern portion of the state.  However, the appearance of city lights in New Orleans is reduced — gaps appear where power outages are likely.  These patchy gaps in city light coverage are consistent with this morning’s power grid status as provided by Entergy, the city’s electric utility.  Although it requires some clear sky data for comparison, VIIRS instrumentation can be used to monitor impacts from storms such as Isaac and to gauge recovery.

VIIRS day-night band radiance imagery over New Orleans on August 27 prior to landfall of Isaac, with New Orleans city lights clustered south of Lake Pontchartrain.

VIIRS day-night band radiance imagery from August 31 following the passage of Isaac. Gaps in New Orleans city lights occur as dark areas within the previous mass of lights in the previous image. Clouds and thunderstorms from Isaac are illuminated by moonlight across northern Louisiana.

Coverage area of New Orleans power grid outages as of 9:00 CDT on August 31 based upon reports from Entergy, the city’s electric utility.  The patchy nature of power outages suggested by VIIRS is consistent with the scattered nature of power outages within the Entergy grid.

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