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Precipitation δ 18 O over the Himalaya‐Tibet orogen from ECHAM5‐wiso simulations: Statistical analysis of temperature, topography and precipitation
Author(s) -
Mutz Sebastian G.,
Ehlers Todd A.,
Li Jingmin,
Steger Christian,
Paeth Heiko,
Werner Martin,
Poulsen Christopher J.
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd024856
Subject(s) - precipitation , plateau (mathematics) , context (archaeology) , climatology , general circulation model , atmospheric sciences , climate change , orogeny , environmental science , isotopes of oxygen , common spatial pattern , geology , physical geography , meteorology , geography , geomorphology , structural basin , mathematical analysis , paleontology , oceanography , mathematics , geochemistry , statistics
Variations in oxygen isotope compositions (δ 18 O) provide insight into modern climate and past changes in climate and topography. In addition, in regions such as Tibet, geologic archives of isotope ratios record climate change driven by plateau uplift and therefore also provide information about the surface uplift history. A good understanding of modern‐day controls on δ 18 O is crucial for interpreting geologic δ 18 O in this context. We use the ECHAM5‐wiso global atmospheric general circulation model to calculate δ 18 O in precipitation (δ 18 O p ) for the present‐day climate. In the region of the Tibetan Plateau, spatial variations of monthly means of δ 18 O p are statistically related to spatial variations of 2 m air temperature and precipitation rate, as well as to topography. The size and location of investigated regions are varied in our study to capture regional differences in these relationships and the processes governing the modern δ 18 O p . In addition to correlation analyses, a cross‐validated stepwise multiple regression is carried out using δ 18 O p as the predictand, and topography and atmospheric variables (temperature and precipitation amount) as predictors. The 2 m air temperature and topography yield the highest spatial correlation coefficients of >0.9 and < −0.9, respectively, throughout most of the year. Particularly high correlation coefficients are calculated for the region along the Himalayan orogeny and parts of western China. The predictors explain >90% of the δ 18 O p spatial variance in the same regions. The 2 m air temperature is the dominant predictor and contributes 93.6% to the total explained spatial variance on average. The results demonstrate that most of the δ 18 O p pattern on and around the Tibetan Plateau can be explained by variation in 2 m air temperature and altitude. Correlation of the dependent predictors indicate that in low‐altitude regions where topography does not determine temperature variability, the high correlation of temperature and δ 18 O p may partially be explained by variations in precipitation rates.