ENSO influence on surface energy and mass balance at Shallap Glacier, Cordillera Blanca, Peru
ENSO influence on surface energy and mass balance at Shallap Glacier, Cordillera Blanca, Peru
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DOI：
10.5194/tc-9-1663-2015
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发表时间：
2015-01-01
期刊：
影响因子：
5.2
通讯作者：
Marzeion, B.
中科院分区：
文献类型：
--
作者：
Maussion, F.;Gurgiser, W.;Marzeion, B.
厄尔尼诺/南方涛动 (ENSO) 是热带安第斯山脉气候变化的主要驱动因素，最近的尼诺和尼娜事件对冰川质量平衡留下了明显的影响。然而，ENSO 与冰川质量平衡之间关系的性质和强度因地区和时间段的不同而有所不同，从而留下了一些关于其确切机制的未解答的问题。这项研究的起点是使用基于过程的模型计算的分布式表面能量和质量平衡 (SEB/SMB) 的 4 年长时间序列，该模型由 Shallap 冰川（秘鲁科迪勒拉布兰卡）的观测驱动。这些数据用于校准基于回归的降尺度模型，该模型将当地 SEB/SMB 通量与每月的大气再分析变量联系起来，从而可以在气候时间尺度（1980-2013 年，ERA-中期）对 ENSO 对 SEB/SMB 的影响进行前所未有的量化。我们发现太平洋海面温度（SST）和冰川质量平衡之间的反相关性比之前报道的更强、更稳定。这种关系在雨季（12 月、5 月）和低海拔地区最为明显，其中尼诺（Nina）事件伴随着降雪不足（过多）和较高（较低）的辐射能量输入。我们检测到 ENSO 与总降水量（尼诺干信号）存在较弱但显着的反相关性，并且与感热通量呈正相关性，但发现 ENSO 对升华没有影响。比较几种降尺度方法和再分析数据集的敏感性分析得出了与太平洋海表温度稳定的质量平衡相关性，但也揭示了计算过去几十年质量平衡趋势的巨大不确定性。新推出的开源缩小尺度工具可以轻松应用于热带地区的其他冰川，从而在更长的时间尺度上开辟新的研究可能性。
The El Nino/Southern Oscillation (ENSO) is a major driver of climate variability in the tropical Andes, where recent Nino and Nina events left an observable footprint on glacier mass balance. The nature and strength of the relationship between ENSO and glacier mass balance, however, varies between regions and time periods, leaving several unanswered questions about its exact mechanisms. The starting point of this study is a 4-year long time series of distributed surface energy and mass balance (SEB/SMB) calculated using a process-based model driven by observations at Shallap Glacier (Cordillera Blanca, Peru). These data are used to calibrate a regression-based downscaling model that links the local SEB/SMB fluxes to atmospheric reanalysis variables on a monthly basis, allowing an unprecedented quantification of the ENSO influence on the SEB/SMB at climatological time scales (1980-2013, ERA-Interim period). We find a stronger and steadier anti-correlation between Pacific sea-surface temperature (SST) and glacier mass balance than previously reported. This relationship is most pronounced during the wet season (December May) and at low altitudes where Nino (Nina) events are accompanied with a snowfall deficit (excess) and a higher (lower) radiation energy input. We detect a weaker but significant ENSO anti-correlation with total precipitation (Nino dry signal) and positive correlation with the sensible heat flux, but find no ENSO influence on sublimation. Sensitivity analyses comparing several downscaling methods and reanalysis data sets resulted in stable mass balance correlations with Pacific SST but also revealed large uncertainties in computing the mass balance trend of the last decades. The newly introduced open-source downscaling tool can be applied easily to other glaciers in the tropics, opening new research possibilities on even longer time scales.