Comparing meteorological records between mountainous and valley bottom sites in the upper reaches of the Heihe River, northwestern China: implications for dendroclimatology

Abstract

Tree-ring records from remote upland areas are widely used in climate reconstructions, but they are typically calibrated by meteorological data from low-lying areas. With the aim of assessing relationships between climatic records from mountainous and valley bottoms, this study compared meteorological records between mountainous sites (lower to upper elevations) and valley bottoms (Qilian (QL) and Yeniugou (YNG)) in the upper reaches of the Heihe River, northwestern China. We found that daily, 5-day, 10-day, and monthly mean air temperatures observed during a 4-year observational period in valley bottoms were strongly correlated (R = 0.90–0.99) to their mountainous site counterparts. Additionally, temperature records from the QL meteorological station shared a higher percentage of variance with each mountainous site compared to YNG. Correlations of precipitation totals between valley bottoms and mountainous sites showed a similar pattern to temperatures. Furthermore, different time series of total rainfall in YNG can explain more variance than those from QL and were also more suitable representations of mountainous sites. Our results confirmed the reliability of utilizing monthly climatic records from valley bottoms to calibrate tree-ring records in mountainous sites. We also caution that when conducting fine-scale microcoring and dendrometer monitoring studies, lower correlations of short-term scale precipitation records between valley bottoms and mountainous sites may introduce unavoidable errors.