We’ve all taken a look at a weather forecast to see how it will affect our day, but for farmers, the weather is very serious business. Farmers know that they’ll need just the right amount of water and the right temperature in order for their crops to thrive.
Floods and droughts can be especially dangerous for the plants that make our food. A team of satellites, called the Joint Polar Satellite System—JPSS for short—is helping to monitor and forecast severe weather conditions on Earth. The more information that farmers have about conditions on Earth, the better they can react to weather disasters.
A farmer digs down to check the soil condition of his crop of tomatoes in Woodland, CA. Image credit: USDA
Watching droughts and floods from space
A drought is a lack of rain in a specific region over months, years—or even decades. Droughts can happen anywhere, but they have a very heavy economic impact in farming regions. In fact, a U.S. drought in 2013 caused more than $10 billion in damage in a single year.
Satellites can give scientists a bird’s eye view of severe weather conditions down here on Earth. Satellites in the JPSS system make these kinds of observations with an instrument called Visible Infrared Imaging Radiometer Suite, or VIIRS.
The VIIRS instrument collects information in two different types of light: visible and infrared. Visible light is the same kind of light that a human eye can see. Scientists can use color in visible light images from VIIRS to keep an eye on lots of things, such as a burst of healthy green plants or the muddy brown water of a flooding river.
California had a years-long drought, followed by lots of rain in early 2017. The VIIRS instrument on Suomi NPP (the first satellite in the JPSS system) captured images before and after the rain. Slide the bar to compare the sediment-filled waterways in the Sacramento Valley on February 11, 2017 (left) and what the same region looked like in November 2016, before the wet weather arrived (right). Credit: NASA Earth Observatory image by Jesse Allen, using VIIRS data from the Suomi National Polar-orbiting Partnership.
VIIRS also captures infrared light, which is invisible to the unaided human eye. However, infrared light images can give scientists important information about our planet—such as changes in the temperature of Earth’s surface.
Caption: Infrared light has less energy than visible light. This type of light is invisible to the human eye, but instruments like VIIRS can detect light in the infrared spectrum. This information helps scientists learn more about our planet.
Monitoring crop health
Together, information from visible and infrared light can be used to determine the health of plants in a certain region. For example, VIIRS can determine how much stress plants are under in a region of extreme drought.
The image below shows California’s central valley—an important farming region—in June of each year during a severe drought. Blue areas show healthy vegetation. Pink areas are where the plants are in extreme stress and/or the surface of the Earth is much warmer than normal. If you take a close look at these images, you can tell that a rain late in the spring of 2015 began providing some relief to the stressed crops in the region.
Credit: NOAA
VIIRS can help scientists to estimate the health and condition of crops during extreme weather conditions, such as drought. Information from VIIRS can also help scientists estimate how a drought or a flood can affect the crops’ anticipated yield (the amount of food that the plants will produce).
This information will help farmers, scientists and policy makers better understand how changes in weather can affect the productivity of crops.