A recent study by NASA scientists may help detect flash drought signals up to three months before they occur, contributing to efforts to mitigate future damage.
Normal droughts can develop slowly over the seasons, whereas flash droughts occur due to rapid drying conditions.
NASA satellites can detect bright light from SIF – (Image: NASA).
According to phys.org on May 14, in a recent study, scientists at the Jet Propulsion Laboratory (JPL) of the National Aeronautics and Space Administration (NASA) were able to detect early flash drought signals by tracking “bright light” from chlorophyll fluorescence (referred to as sun-induced fluorescence – SIF).
Chlorophyll emits light when exposed to sunlight during photosynthesis. The stronger the fluorescence, the more carbon dioxide plants absorb from the air for growth.
Although invisible to the naked eye, this bright light can be detected by instruments on satellites, such as NASA’s Orbiting Carbon Observatory-2.
The research team compared fluorescence data with flash drought data in the United States from May to July during the years 2015 to 2020.
They discovered a domino effect when they noted that in the weeks and months leading up to flash droughts, vegetation initially thrived as weather conditions turned warmer and drier. The robust plants emitted unusually strong fluorescence signals at this time of year.
As extreme temperatures set in, soil moisture, which was already low, decreased further, leading to the occurrence of flash droughts.
The research team correlated the fluorescence data with soil moisture data from NASA satellites. They found that unusual fluorescence levels were closely related to soil moisture loss about 6-12 weeks before a flash drought event occurred.
They examined this relationship across various terrains, from forests in the eastern U.S. to the Great Plains and shrublands in the west, with consistent results.
A field preparing for the planting season in Kentucky, USA – (Image: U.S. Department of Agriculture).
For this reason, SIF “promises to be a reliable early warning signal for flash droughts with enough time to act,” said scientist Nicholas Parazoo, the lead author of the study.
While early warnings cannot eliminate the impacts of flash droughts, they can help farmers and landowners proactively increase irrigation to mitigate effects on crops.
Rapidly emerging and often with little warning, the flash drought that occurred across much of the United States in 2012 was caused by extreme heat, which depleted moisture from the soil and crops, resulting in widespread crop failures and economic losses exceeding $30 billion.
