The isotopic signal (δ¹⁸O and δD) imprinted in ice cores from Antarctica is not solely generated by the temperature sensitivity of the isotopic composition of precipitation, but it also contains the signature of the intermittency of the precipitation patterns, as well as of post-deposition processes occurring at the surface and in the firn. This leads to a proxy signal recorded by the ice cores that may not be representative of the local climate variations. Due to precipitation intermittency, the ice cores only record brief snapshots of the climatic conditions, resulting in aliasing of the climatic signal and thus a large amount of noise which reduces the minimum temporal resolution at which a meaningful signal can be retrieved. The analyses are further complicated by isotopic diffusion, which acts as a low-pass filter that dampens any high-frequency changes. Here, we use reanalysis data (ERA-Interim) combined with satellite products of accumulation to evaluate the spatial distribution of the numerical estimates of the transfer function that describes the formation of the isotopic signal across Antarctica. As a result, the minimum timescales at which the signal-to-noise ratio exceeds unity range from less than 1 year at the coast to about 1000 years further inland. Based on solely physical processes, we are thus able to define a lower bound for the timescales at which climate variability can be reconstructed from the isotopic composition in ice cores.

中文翻译：

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冰芯中存储的气候信息：间断性和扩散对南极记录的同位素信号的影响

同位素信号（δ ¹⁸ ö和δ d）印在南极冰芯中的原因不仅是由沉淀的同位素组成的温度敏感性产生的，而且还包含降水模式的间歇性特征以及在地表和地面上发生的沉积后过程的特征。开枪。这导致由冰芯记录的替代信号可能无法代表当地的气候变化。由于降水的间歇性，冰芯仅记录了气候条件的简短快照，从而导致了气候信号的混叠，并因此产生了大量的噪声，从而降低了可用来检索有意义信号的最小时间分辨率。同位素扩散使低通滤波器变得更加复杂，同位素扩散充当了抑制任何高频变化的低通滤波器。这里，我们使用再分析数据（ERA-Interim）结合累积的卫星积来评估传递函数数值估计值的空间分布，该函数描述了横跨南极洲的同位素信号的形成。结果，信噪比超过1的最小时间范围从海岸的不到1年到内陆的大约1000年。因此，仅基于物理过程，我们就可以为可从冰芯中的同位素组成重建气候变异性的时间范围定义下限。信噪比超过1的最小时间范围从海岸不到1年到内陆约1000年。因此，仅基于物理过程，我们就可以为可从冰芯中的同位素组成重建气候变异性的时间范围定义下限。信噪比超过1的最小时间范围从海岸不到1年到内陆约1000年。因此，仅基于物理过程，我们就可以为可从冰芯中的同位素组成重建气候变异性的时间范围定义下限。