Dynamics, Variability, and Change in Seasonal Precipitation Reconstructions for North America
Dynamics, Variability, and Change in Seasonal Precipitation Reconstructions for North America
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DOI：
10.1175/jcli-d-19-0270.1
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发表时间：
2020-04-01
影响因子：
4.9
通讯作者：
Crawford, Christopher J.
中科院分区：
文献类型：
--
作者：
Stahle, David W.;Cook, Edward R.;Crawford, Christopher J.
冷季和暖季降水总量已重建网格的基础上，北美使用439树轮年表与12月至4月的总量和547个不同的年表与5月至7月的总量。这些离散的季节年表与交替的季节没有显著的相关性; 12月至4月的重建在美国南部和西部大部分地区以及墨西哥中北部都很熟练，而5月至7月的估计在美国大部分地区，加拿大西南部和墨西哥东北部都很熟练。无论是强大陆范围内的厄尔尼诺南方涛动（ENSO）信号嵌入在冷季重建和北极涛动信号登记的暖季估计忠实地再现的迹象，强度和空间格局，这些海洋大气对北美降水的影响与仪器数据记录。重建包括在北美季节性降水地图集（NASPA），并提供洞察十年干旱和多雨。它们表明，16世纪的特大干旱是过去500年来最严重和持续的北美干旱，是三种不同的季节性干旱的综合结果，每种干旱都具有独特的空间模式，可能与ENSO、北极涛动和大西洋数十年振荡的季节性强迫有关。在北美东部的冷季和暖季重建中，发现了长达200-500年的降水增加的显着趋势。这些季节性降水变化似乎是东部地区其他古气候代理中测得的正水分趋势的一部分，该趋势始于工业革命前的自然强迫，最近可能被人为气候变化所增强。
Cool- and warm-season precipitation totals have been reconstructed on a gridded basis for North America using 439 tree-ring chronologies correlated with December-April totals and 547 different chronologies correlated with May-July totals. These discrete seasonal chronologies are not significantly correlated with the alternate season; the December-April reconstructions are skillful over most of the southern and western United States and north-central Mexico, and the May-July estimates have skill over most of the United States, southwestern Canada, and northeastern Mexico. Both the strong continent-wide El Nino-Southern Oscillation (ENSO) signal embedded in the cool-season reconstructions and the Arctic Oscillation signal registered by the warm-season estimates faithfully reproduce the sign, intensity, and spatial patterns of these ocean-atmospheric influences on North American precipitation as recorded with instrumental data. The reconstructions are included in the North American Seasonal Precipitation Atlas (NASPA) and provide insight into decadal droughts and pluvials. They indicate that the sixteenth-century megadrought, the most severe and sustained North American drought of the past 500 years, was the combined result of three distinct seasonal droughts, each bearing unique spatial patterns potentially associated with seasonal forcing from ENSO, the Arctic Oscillation, and the Atlantic multidecadal oscillation. Significant 200-500-yr-long trends toward increased precipitation have been detected in the cool- and warm-season reconstructions for eastern North America. These seasonal precipitation changes appear to be part of the positive moisture trend measured in other paleoclimate proxies for the eastern area that began as a result of natural forcing before the industrial revolution and may have recently been enhanced by anthropogenic climate change.