Earth Notes: Drought Eye

Jun 26, 2019

Drought in the Southwest is something people want to track—and temperature is one way to do that. All over the United States, space satellites and weather stations collect temperature data in real time. But processing and presenting that data can take a long time. That’s why researchers created an interactive online map called Drought Eye. 

Drought map, November 2018
Credit Drought Eye

The map displays a measurement of “thermal stress” as a proxy for drought conditions. It shows the difference in temperature between the air, and the plant canopies on the earth’s surface.

On normal days, plants open tiny pores called stomata, allowing water to evaporate and creating a cooling effect. But when water is scarce, plants close their stomates and the canopy begins to heat up. So comparing surface and air temperatures can reveal when plants are stressed.

The bare, rocky ground of the Colorado Plateau naturally has more thermal stress than forests and grasslands. Drought Eye shows the anomaly—the difference from the average.

The color-coded map uses deep purple to indicate drought-stressed regions, fading to orange and yellow for normal to wet areas. In November 2018, much of the West was covered in purple. That’s when the Camp Fire burned—the most destructive wildfire in California’s history.

The map’s creators want to use the information to improve predictions for wildfires. There are other applications, too. Conservation biologists can track how plant and animal species begin to move across the landscape in response to drought. Farmers can see where crops are struggling.

And anyone who just wants to see what’s happening can access Drought Eye on a free website that updates every month.