TY - JOUR
T1 - Global sinusoidal seasonality in precipitation isotopes
AU - Allen, Scott T.
AU - Jasechko, Scott
AU - Berghuijs, Wouter R.
AU - Welker, Jeffrey M.
AU - Goldsmith, Gregory R.
AU - Kirchner, James W.
PY - 2019/8/21
Y1 - 2019/8/21
N2 - Quantifying seasonal variations in precipitation δ2H and δ18O is important for many stable isotope applications, including inferring plant water sources and streamflow ages. Our objective is to develop a data product that concisely quantifies the seasonality of stable isotope ratios in precipitation. We fit sine curves defined by amplitude, phase, and offset parameters to quantify annual precipitation isotope cycles at 653 meteorological stations on all seven continents. At most of these stations, including in tropical and subtropical regions, sine curves can represent the seasonal cycles in precipitation isotopes. Additionally, the amplitude, phase, and offset parameters of these sine curves correlate with site climatic and geographic characteristics. Multiple linear regression models based on these site characteristics capture most of the global variation in precipitation isotope amplitudes and offsets; while phase values were not well predicted by regression models globally, they were captured by zonal (0-30° and 30-90°) regressions, which were then used to produce global maps. These global maps of sinusoidal seasonality in precipitation isotopes based on regression models were adjusted for the residual spatial variations that were not captured by the regression models. The resulting mean prediction errors were 0.49% for δ18O amplitude, 0.73% for δ18O offset (and 4.0 % and 7.4 % for δ2H amplitude and offset), 8 d for phase values at latitudes outside of 30°, and 20 d for phase values at latitudes inside of 30°. We make the gridded global maps of precipitation δ2H and δ18O seasonality publicly available. We also make tabulated site data and fitted sine curve parameters available to support the development of regionally calibrated models, which will often be more accurate than our global model for regionally specific studies.
AB - Quantifying seasonal variations in precipitation δ2H and δ18O is important for many stable isotope applications, including inferring plant water sources and streamflow ages. Our objective is to develop a data product that concisely quantifies the seasonality of stable isotope ratios in precipitation. We fit sine curves defined by amplitude, phase, and offset parameters to quantify annual precipitation isotope cycles at 653 meteorological stations on all seven continents. At most of these stations, including in tropical and subtropical regions, sine curves can represent the seasonal cycles in precipitation isotopes. Additionally, the amplitude, phase, and offset parameters of these sine curves correlate with site climatic and geographic characteristics. Multiple linear regression models based on these site characteristics capture most of the global variation in precipitation isotope amplitudes and offsets; while phase values were not well predicted by regression models globally, they were captured by zonal (0-30° and 30-90°) regressions, which were then used to produce global maps. These global maps of sinusoidal seasonality in precipitation isotopes based on regression models were adjusted for the residual spatial variations that were not captured by the regression models. The resulting mean prediction errors were 0.49% for δ18O amplitude, 0.73% for δ18O offset (and 4.0 % and 7.4 % for δ2H amplitude and offset), 8 d for phase values at latitudes outside of 30°, and 20 d for phase values at latitudes inside of 30°. We make the gridded global maps of precipitation δ2H and δ18O seasonality publicly available. We also make tabulated site data and fitted sine curve parameters available to support the development of regionally calibrated models, which will often be more accurate than our global model for regionally specific studies.
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U2 - 10.5194/hess-23-3423-2019
DO - 10.5194/hess-23-3423-2019
M3 - Article
AN - SCOPUS:85071237132
SN - 1027-5606
VL - 23
SP - 3423
EP - 3436
JO - Hydrology and Earth System Sciences
JF - Hydrology and Earth System Sciences
IS - 8
ER -