Mechanisms of a meteorological drought onset: summer 2020 to spring 2021 in southwestern North America
Mechanisms of a meteorological drought onset: summer 2020 to spring 2021 in southwestern North America
复制标题
DOI：
10.1175/jcli-d-22-0314.1
复制
发表时间：
2022-08
影响因子：
4.9
通讯作者：
R. Seager;M. Ting;P. Alexander;J. Nakamura;Haibo Liu;Cuihua Li;I. Simpson
中科院分区：
文献类型：
--
作者：
R. Seager;M. Ting;P. Alexander;J. Nakamura;Haibo Liu;Cuihua Li;I. Simpson
到2021年夏季，中度至异常干旱影响了北美28%的地区，主要集中在密西西比河以西，对火灾、水资源和农业造成严重影响。在这里，使用再分析和SST强迫气候模型，我们研究了西南干旱从2020年夏季开始到2020-21年冬季和春季的开始和发展。2021年夏季的干旱严重程度是由于美国西南部连续四个季节的降水量是有记录以来最低的，或者至少是极端干燥。2020年夏季的干燥状况是由内部大气变化引起的，但超出了所研究的大气模型模拟该季节的范围。从2020年冬季到2021年春季，热带太平洋拉尼娜现象的发展导致了干旱状况的恶化。太平洋的年代际变化在过去二十年中推动了冷季变得更干燥，从而助长了该区域南部的干旱。还有证据表明，由于人为气候变化，春季该地区南部正在干燥。总之，干旱的发生是由内部大气变率和年际气候变率共同驱动的，并得到自然的十年变率和人为气候变化的帮助。
By summer 2021 moderate to exceptional drought impacted 28% of North America, focused west of the Mississippi, with serious impacts on fire, water resources and agriculture. Here, using reanalyses and SST-forced climate models, we examine the onset and development of this southwestern drought from its inception in summer 2020 through winter and spring 2020-21. The drought severity in summer 2021 resulted from four consecutive prior seasons in which precipitation in the southwest United States was the lowest on record or, at least, extremely dry. The dry conditions in summer 2020 arose from internal atmospheric variability but are beyond the range of what the studied atmosphere models simulate for that season. From winter 2020 through spring 2021 the worsening drought conditions were guided by the development of a La Niña in the tropical Pacific Ocean. Decadal variability in the Pacific Ocean aided drought in the southern part of the region by driving the cool-season to be drier during the last two decades. There is also evidence that the southern part of the region in spring is drying due to human-driven climate change. In sum the drought onset was driven by a combination of internal atmospheric variability and interannual climate variability and aided by natural decadal variability and human-driven climate change.