Interdecadal variability of the austral summer precipitation over the Central Andes
Interdecadal variability of the austral summer precipitation over the Central Andes
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DOI：
10.3389/feart.2022.954954
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发表时间：
2022-09
期刊：
影响因子：
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通讯作者：
Juan C. Sulca;M. Vuille;B. Dong
中科院分区：
文献类型：
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作者：
Juan C. Sulca;M. Vuille;B. Dong
基于逐月格点降水资料和低通滤波后的Niño 4指数（IN4）、Niño 1+2指数（IN1+2*）、大西洋多年代际涛动（AMO）和太平洋年代际涛动（IPO）指数时间序列，研究了1921-2010年南方夏季（12月- 1 - 2月，DJF）太平洋和大西洋年代际变率对安第斯中部降水的影响。以及大西洋海温距平年代际分量的前三个旋转主分量。对安第斯山脉中部（10°S - 30°S）降水进行旋转经验正交函数（REOF）分析，得到两个主要模态RPC1和RPC2，分别占总方差的40.4%和18.6%。REOF1在玻利维亚北部和智利高原之间具有降水偶极子。REOF2还具有降水偶极子，在秘鲁安第斯山脉南部负载荷最高。REOF1正相与水汽从低地向玻利维亚高原输送有关，这是由安第斯山脉中部上空的高层东风异常引起的。与此同时，秘鲁安第斯山脉南部的气候趋于干燥。REOF2正相与秘鲁高空西风异常引起的水汽输送减弱有关。首次公开募股暖期通过安第斯山脉中部上空的高层西风异常，引起玻利维亚高原明显的干燥异常，尽管弱于IN4暖期。安第斯山脉中部降水与AMO在年代际时间尺度上无显著关系。
The impacts of the interdecadal variability of the Pacific and the Atlantic Oceans on precipitation over the Central Andes during the austral summer (December-January-February, DJF) are investigated for the 1921–2010 period based on monthly gridded precipitation data and low-pass filtered time series of the Niño 4 index (IN4), the Niño 1 + 2 index with Niño 3.4 index removed (IN1+2*), Atlantic Multidecadal Oscillation (AMO), and Interdecadal Pacific Oscillation (IPO) indices, and the three first rotated principal components of the interdecadal component of the sea surface temperature (SST) anomalies over the Atlantic Ocean. A rotated empirical orthogonal function (REOF) analysis of precipitation in the Central Andes (10°S–30°S) yields two leading modes, RPC1 and RPC2, which represent 40.4% and 18.6% of the total variance, respectively. REOF1 features a precipitation dipole between the northern Bolivian and the Chilean Altiplano. REOF2 also features a precipitation dipole, with highest negative loading over the southern Peruvian Andes. The REOF1 positive phase is associated with moisture transport from the lowlands toward the Bolivian Altiplano, induced by upper-level easterly wind anomalies over the Central Andes. At the same time conditions tend to be dry over the southern Peruvian Andes. The positive phase of REOF2 is related to weakened moisture transport, induced by upper-level westerly wind anomalies over Peru. The IPO warm phase induces significant dry anomalies over the Bolivian Altiplano, albeit weaker than during the IN4 warm phase, via upper-level westerly wind anomalies over the Central Andes. No significant relationship was found between Central Andean precipitation and the AMO on interdecadal timescales.