The summer precipitation response of latewood tree‐ring chronologies in the southwestern United States
The summer precipitation response of latewood tree‐ring chronologies in the southwestern United States
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DOI：
10.1002/joc.6997
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发表时间：
2021-01
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影响因子：
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通讯作者：
I. Howard;D. Stahle;M. Torbenson;D. Griffin
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文献类型：
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作者：
I. Howard;D. Stahle;M. Torbenson;D. Griffin
美国西南部干旱地区针叶树晚材宽度年轮年表与夏季季风季节部分地区的降水量相关。季风季节的开始日期和长度在整个地区各不相同，这些夏季降雨气候学的区域差异可能会影响晚材年表的暖季降水响应的强度和时间。最佳晚材夏季降水的响应计算每天使用67调整晚材年表（LWa）从美国西南部，调整，以消除与先前早材生长的相关性。大多数LWa年表显着相关的降水量总结在一段时间内约4周（29天），在初夏。这种初夏降水信号是目前在整个研究区域的黄松年表。这在道格拉斯冷杉年表中也很明显，但仅限于亚利桑那州南部和新墨西哥州。在美国西南部的仪器降水数据中，夏季降水开始的儒略日期从南到北增加。在大多数LWa年表中，初夏季节降水响应的时间也往往发生在夏季晚些时候，从亚利桑那州东南部到北方新墨西哥州和科罗拉多东部。LWa年表的主成分分析再现了仪器数据中看到的初夏降水协变的三个最重要的空间模式中的两个。LWa的第一个PC与仪器初夏降水的PC 1相关的相同大气环流特征有关，包括美国西南部的气旋环流和东太平洋的水汽平流。使用仪器和树木年轮重建的降水量对前期冷季降水和初夏降水之间的相关性分析表明，树木年轮数据再现了仪器数据中季节之间相关性的多年变化。
Latewood width tree‐ring chronologies from arid‐site conifers in the southwestern United States are correlated with precipitation during portions of the summer monsoon season. The onset date and length of the monsoon season varies across the region, and these regional differences in summer rainfall climatology may impact the strength and timing of the warm season precipitation response of latewood chronologies. The optimal latewood response to summer precipitation is computed on a daily basis using 67 adjusted latewood chronologies (LWa) from the southwestern United States, adjusted to remove correlation with preceding earlywood growth. Most LWa chronologies are significantly correlated with precipitation summed over a period of approximately 4 weeks (29 days) in early summer. This early summer precipitation signal is present in most ponderosa pine chronologies across the study area. It is also evident in Douglas‐fir chronologies, but only from southern Arizona and New Mexico. The Julian date of summer precipitation onset increases from south to north in the instrumental precipitation data for the southwestern United States. The timing of the early summer season precipitation response in most LWa chronologies also tends to occur later in the summer from southeastern Arizona into northern New Mexico and eastern Colorado. Principal components analysis of the LWa chronologies reproduces two of the three most important spatial modes of early summer precipitation covariability seen in the instrumental data. The first PC of LWa is related to the same atmospheric circulation features associated with PC1 of instrumental early summer precipitation, including cyclonic circulation over the southwestern United States and moisture advection from the eastern Pacific. Correlation analyses between antecedent cool season precipitation and early summer rainfall using instrumental and tree‐ring reconstructed precipitation indicates that the tree‐ring data reproduce the multi‐decadal variability in correlation between seasons seen in the instrumental data.