NASA Satellites See the Effects of Rainfall on the 2019 Alaska Wildfire Season

July 25, 2019

NASA Satellites See the Effects of Rainfall on the 2019 Alaska Wildfire Season

Video of rain patterns during an active fire season: Alaska, summer 2019. Credit: Owen Kelley, Jacob Reed, NASA GSFC

NASA’s satellite-based estimates of global precipitation can provide valuable information to officials monitoring the many wildfires that have been scorching Alaska this summer. Although wildfires regularly occur every Alaskan summer, July 2019 proved a particularly active month. 

Few rain gauges exist in the remote expanses of Alaskan wilderness, but wildfires unchecked can spread to populated areas within the state. Satellite-based precipitation estimates are therefore particularly valuable because of precipitation's relationship to wildfire hazard. The embedded video, above, shows data compiled from observations made by NASA's Integrated Multi-satellite Retrievals for Global Precipitation Measurement, or IMERG, part of the Global Precipitation Measurement satellite constellation that employs active and passive sensors to remotely record precipitation amounts worldwide. 

Precipitation amounts are noted above for the period May 1 through July 18. The total accumulation since May 1 is shown in millimeters (inches) on the left half, while the accumulation during a 3-hour period is shown on the right half.  The locations of likely fires are shown in red, based on thermal anomalies observed by the Visible Infrared Imaging Radiometer Suite (VIIRS), one of the key instruments onboard the Suomi National Polar-Orbiting Partnership (Suomi NPP) satellite.  

The VIIRS “hot spot” data has a resolution of approximately 0.25 square kilometers and is based on infrared brightness temperature. Locations of lightning strikes are shown in yellow, as detected by the network of ground sensors that make up the World Wide Lightning Location Network (WWLLN). A flash is detected when five or more WWLLN stations around the world detect a radio-frequency atmospheric signal from the same lightning strike. 

A gray circle along the southern coast or center of Alaska represents the cities of Anchorage or Fairbanks, respectively. The first part of the movie covers the month of May: a period of scant precipitation, little lightning and few wildfires. June shows an increasing amount of lightning but still few fires. During June, the storms that did pass through central Alaska delivered roughly half the normal amount of precipitation, according to NOAA's Climate Prediction Center. 

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