The researchers compared years of fluorescence data to an inventory of flash droughts that struck the U.S. between May and July from 2015 to 2020. They found a domino effect: In the weeks and months leading up to a flash drought, vegetation initially thrived as conditions turned warm and dry. The flourishing plants emitted an unusually strong fluorescence signal for the time of year.
研究人員將多年的熒光數(shù)據(jù)與2015年至2020年5月至7月期間襲擊美國(guó)的突發(fā)干旱清單進(jìn)行了比較.他們發(fā)現(xiàn)了多米諾骨牌效應(yīng):在突發(fā)干旱之前的幾周和幾個(gè)月里,隨著條件的轉(zhuǎn)變,植被最初蓬勃發(fā)展,溫暖干燥。這些茂盛的植物在一年中的這個(gè)時(shí)候會(huì)發(fā)出異常強(qiáng)烈的熒光信號(hào)。
But by gradually drawing down the water supply in the soil, the plants created a risk. When extreme temperatures hit, the already low moisture levels plummeted, and flash drought developed within days.The team correlated the fluorescence measurements with moisture data from NASA’s SMAP satellite. Short for Soil Moisture Active Passive, SMAP tracks changes in soil water by measuring the intensity of natural microwave emissions from Earth’s surface.
但隨著逐漸減少土壤中的水供應(yīng),這些植物造成了風(fēng)險(xiǎn)。當(dāng)極端氣溫襲來(lái)時(shí),本來(lái)就很低的濕度急劇下降,幾天之內(nèi)就會(huì)出現(xiàn)干旱.研究小組將熒光測(cè)量值與美國(guó)宇航局 SMAP 衛(wèi)星的濕度數(shù)據(jù)相關(guān)聯(lián)。SMAP 是土壤濕度主動(dòng)被動(dòng)的縮寫(xiě),通過(guò)測(cè)量地球表面自然微波發(fā)射的強(qiáng)度來(lái)跟蹤土壤水分的變化。
The scientists found that the unusual fluorescence pattern correlated extremely well with soil moisture losses in the six to 12 weeks before a flash drought. A consistent pattern emerged across diverse landscapes, from the temperate forests of the Eastern U.S. to the Great Plains and Western shrublands.
科學(xué)家發(fā)現(xiàn),這種不尋常的熒光模式與突發(fā)干旱前 6 至 12 周的土壤水分損失密切相關(guān)。從美國(guó)東部的溫帶森林到大平原和西部灌木叢,不同的景觀(guān)都出現(xiàn)了一致的模式。