Please ensure Javascript is enabled for purposes ofwebsite accessibility

NASA study uses satellite data to estimate August 2020 Derecho crop damage


Derecho IR satellite imagery
Derecho IR satellite imagery
Facebook Share IconTwitter Share IconEmail Share Icon

A study published in the Bulletins of the American Meteorological Society is taking a new approach to estimate crop damage caused by the August 2020 Derecho.

The study, led by several NASA scientists across the country, identified damage using satellite data, then used a specific type of satellite instrument, called a Synthetic Aperture Radar (SAR), to calculate a damage estimate.

"A lot of times with hail damage you see that crops have been shredded because you have a lot of wind-driven hail, so you get a lot of the leaves that are shredded, the stalks are shredded," explains Jordan Bell, a Remote Sensing Scientist at NASA Marshall Space Flight Center. "Here it was very unique because you had very rich green vegetation laying over."

Using SAR onboard a Sentinel satellite, Bell and his team analyzed the data as the satellite passed over Iowa in the days following the derecho and compared it to what it looked like before the derecho. Like the International Space Sation, this satellite orbits over small pieces of the earth at a time, scanning the surface and recording the energy reflected back.

"Some satellites are geostationary so they look at the same place at the same time all the time," explains Dr. Sarah Bang, another Remote Sensing Scientist at NASA Marshall Space Flight Center. "Whereas some satellites like the ones I use are in an inclined orbit so they sample when they sample and you’re kind of looking for a needle in a moving haystack."

"We were able to compare areas that weren’t impacted, so the backscatter, what their returns were looking like to the sensor, and compare those to the areas that were blown over, and what we found out was they had a different return signal, so that’s how we were able to get our damage estimate," says Bell.

Using their findings, the team worked in conjunction with the Iowa Department of Agriculture and Land Stewardship to estimate the total damage to the state's two key crops: corn and soybeans.

They estimated 1.97 million acres of corn and 1.40 million acres of soybean crop were damaged or destroyed. The damage estimates generated by this study were comparable to estimates produced by others after the derecho, including two commercial agricultural companies.

The scope of their study was not limited to just crop damage. The ultimate goal in a study like this looks to the future and how satellite data can be used to better respond to disasters and better predict disasters.

Kristopher Bedka, a Research Scientist at NASA Langley Research Center, analyzed GOES (geostationary) satellite data to find how it correlated with damage reported on the ground.

"We really wanted to use this state of the art data to understand the strengths and some of the limitations of being able to map out these severe storm cells and then being able to correlate the patterns we’re seeing on the satellite image with the damage that was generated on the ground, whether it be from wind, hail, or a few tornadoes that were scattered throughout the event," says Bedka.

What he found was actually a bit counterintuitive. The coldest (tallest and most intense) thunderstorms were often offset a few miles from the most significant damage.

"This study has really opened my eyes with regards to how we can design algorithms of the future to automatically identify severe storms," says Bedka. "It’s not always a good assumption to basically imply that coldest, deepest clouds will always be associated with the most intense and impactful weather."

As satellite technology continues to improve, the team hopes to show studies like these can be an example for how to respond to weather disasters in the future. One example in the derecho was what appeared to be tornado tracks sweeping across cornfields. Using satellite data, the team was able to pinpoint the damage to something manmade.

"The [NWS] Des Moines office saw these tracks in cornfields where more damage was occurring and then went back using satellites and were able to find out exactly how grain bins were rolling up to a mile through these different cornfields and leaving tracks just like tornadoes," says Christopher Schultz, a research meteorologist at NASA Marshall Space Flight Center.

"If you go back 50 years, this type of event, you would not have as much detail in the impact and a lot of the details would get lost. And now we’re able to estimate loss and help in the recovery process much faster than 50 years ago when this satellite technology didn’t exist," says Schultz.

Another big impact following the derecho was the ensuing power outages and hot weather. Severe outages like these can also be seen from space.

"Immediately after the impacts, I believe it got very hot for several weeks after the event up there, and there were a ton of power outages," recalls Bell. "In addition to the utility companies working as fast as they can, we were able to monitor the power recovery from satellite imagery simply by just observing the lights that are available and seen at night."

Each satellite was designed for a specific purpose. Dr. Bang says using them together can teach us a lot about forecasting and responding to severe weather.

"Working with all these satellites in concert, strengths of one can overcome the weaknesses of the other, because they were designed to do different things and it gives you a much more complete picture of what’s going on. This event, the perspective, the view, and the timing of this event is going to teach us so much about severe weather for decades," Bang says.

If you would like to read the full study, including more information about their crop damage estimate. click here.

Loading ...