LNU Lightning Complex Fire

First Posting | Summary
Posting Date: September 3, 2020, 9:00:00 AM

The LNU Lightning Complex Fire (comprising the Hennessey, Gamble, Spanish, Markley, and Walbridge fires) in Northern California started at 6:40 a.m. PDT on August 17 after lightning strikes set fire to vegetation—mostly chaparral, high grasses, and timber—in Napa and Sonoma counties. The fires then spread to Lake, Solano and Yolo counties.

ALERT™ subscribers can download a Touchstone^®-ready burn scar shapefile, valid as of September 1, from the Downloads tab that can be used in our Geospatial Analytics Module or other GIS applications to better understand their potential impacts from the LNU fire. (For more information, please refer to “The LNU Lightning Complex Burn Scar Shapefile FAQs” section below.)

The LNU Lightning Complex Fire has become the third largest wildfire in the State of California’s recorded history—after the #1 Mendocino Complex Fire in 2018, which burned 459,123 acres yet is not one of the top 20 most destructive fires, and the #2 SCU Lightning Complex Fire, which has burned 390,157 acres to date but has destroyed relatively few structures. The LNU Lightning Complex Fire is to date also the 10^th most destructive fire in the State of California’s recorded history.

As of 7 p.m. PDT on September 2, according to CAL FIRE, the LNU Complex Fire had burned 375,209 acres and was 78% contained. This fire has destroyed 1,464 structures, mostly in Napa and Solano counties: 772 single-family homes, 11 commercial structures, 1 mixed commercial structure, and 680 other structures. In addition, 231 structures were damaged, mostly in Napa and Solano counties: 111 single-family homes, 3 commercial structures, and 117 other structures. Five civilian casualties have been reported, three of them in Napa County and the other two in Solano County.

The LNU Lightning Complex Burn Scar Shapefile FAQs

What is it?

AIR created the LNU Lightning Complex burn scar shapefile, valid as of September 1, to represent our best estimate of the actual area burned by this fire within the National Interagency Fire Center (NIFC) fire perimeters using publicly available optical and radar satellite imagery. To provide estimates of the burned areas, AIR developed a burn estimation method based on historical fires and validated with CAL FIRE data on damaged structures.

What is AIR’s methodology for producing it?

Under clear weather conditions, our methodology takes advantage of the reliable normalized difference burn ratio (dNBR) from optical satellite imagery, such as Sentinel-2 operated by the European Space Agency (ESA) or Landsat-8. To overcome smoke and cloud limitations associated with optical imagery, we supplement with interferometric coherence change from ESA’s radar mission Sentinel-1 Single Look Complex product. Our burn estimation method uses these two complementary satellite sources, and refines estimation with cover classes from the National Land Cover Database (NLCD). The burn scar was further enhanced by incorporating the LNU Lightning Complex Damage Inspection Database (DINS), which captures the location and damage status of structures.

How does AIR’s burn scar shapefile differ from publicly available shapefiles?

The burn scar shapefile AIR provides represents our best estimate of the actual area burned by a given fire. This is different from what formerly was known as GeoMAC and what CAL FIRE now provides in that those products focus solely on the fire perimeter whereas we are identifying areas that are unburned as well as burned within the perimeter. AIR creates our burn scar using both visual satellite and InSAR data; the latter helps us surmount the issue of difficulties caused by smoke and clouds that can hamper use of the visual data. 

Regards,

AIR ALERT Team

First Posting | Downloads
Posting Date: September 3, 2020, 9:00:00 AM

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