Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, 010018 Hohhot, China.
Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, 010018 Hohhot, China.
Sci Total Environ. 2022 Nov 25;849:157923. doi: 10.1016/j.scitotenv.2022.157923. Epub 2022 Aug 8.
At present, flash droughts are poorly understood. Mature prevention and control measures are not available. This study aims to thoroughly explore the evolution characteristics of flash droughts in grassland ecosystems and to determine the meteorological driving conditions for inducing and relieving flash droughts. We propose the concept of the strong evapotranspiration flash drought (SEFD), a new type of flash drought in mid-temperate grasslands. The frequency of SEFDs is lower than that of heat wave flash droughts (HWFDs), but the intensity and impact of SEFDs are greater than those of HWFDs. Flash droughts in grasslands exhibit a high outbreak period from May to August, with the intensity basically above that of moderate drought. HWFDs occur most frequently in June and SEFDs in May. Meadow grasslands are the type of grassland with the highest risk of flash drought. Typical grasslands are more prone to HWFDs, while desert grasslands are more prone to SEFD outbreaks. In this study, a multifactor method was established to quantitatively evaluate the key influencing factors inducing flash droughts of different intensities in different time periods and to quantitatively predict the evolution of flash droughts into seasonal droughts. The temperature, water vapor pressure, precipitation, and wind speed were the key influencing factors of flash droughts and that the most important period in terms of inducing flash droughts is one pentad before the onset of flash drought. The outbreak rate and threshold of key influencing factors are the driving conditions for inducing flash droughts, and the recovery rate can be used as the basis for predicting whether an flash drought will evolve into a seasonal drought. The results showed that the characteristics and driving conditions of flash droughts are different in different types of grasslands and different time periods and are different for different types of flash droughts. In the future, the impact of flash droughts will become more severe.
目前，对闪蒸干旱的了解还很不完善，也没有成熟的防控措施。本研究旨在深入探讨草原生态系统闪蒸干旱的演变特征，确定诱发和缓解闪蒸干旱的气象驱动条件。我们提出了强蒸散闪蒸干旱（SEFD）的概念，这是一种中温带草原的新型闪蒸干旱。SEFD 的频率低于热浪闪蒸干旱（HWFD），但 SEFD 的强度和影响大于 HWFD。草原闪蒸干旱高发期为 5 月至 8 月，强度基本在中度干旱以上。HWFD 最常发生在 6 月，SEFD 最常发生在 5 月。草地草原是闪蒸干旱风险最高的草原类型。典型草原更容易发生 HWFD，而沙漠草原更容易发生 SEFD。本研究建立了一种多因素方法，用于定量评估不同时间和不同强度闪蒸干旱的关键影响因素，并定量预测闪蒸干旱向季节性干旱的演变。温度、水汽压、降水和风速是闪蒸干旱的关键影响因素，诱发闪蒸干旱最重要的时期是闪蒸干旱发生前的一个五倍期。关键影响因素的爆发率和阈值是诱发闪蒸干旱的驱动条件，恢复率可作为预测闪蒸干旱是否演变为季节性干旱的依据。结果表明，不同类型草原和不同时期闪蒸干旱的特征和驱动条件不同，不同类型闪蒸干旱的特征和驱动条件也不同。未来，闪蒸干旱的影响将更加严重。
