Detection of Climate Signal by Inter-stake Correlations of Annual Ablation Data Qamanârssûp Sermia, West Greenland

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Abstract
Annual ablation on Qamanârssûp sermia, West Greenland, varies with year and location. The time variation of ablation at any stake consists of climate signal and noise due to errors and local topography. Variations of ablation at different stakes are positively correlated with each other with inter-stake correlation coefficients depending on the relative magnitudes of climate signal and noise. Inter-stake correlations and noise are very sensitive to gross errors in the data, while climate signal is less sensitive. Low values of inter-stake correlations are used to detect suspect data, and elimination of such data reduces the noise standard deviation from ±0.40 to ±0.28 m water a−1 for 6 years of record compared with a climate signal of ±0.55 m water a−1. The climate signal on Qamanârssûp is positively correlated with summer mean temperature and negatively correlated with annual precipitation. This shows that even a sparse stake network as at Qamanârssûp sermia gives useful glacier-climate information which can be applied to studies of both glacier hydrology and greenhouse effect.