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GEOPHYSICAL RESEARCH LETTERS,
VOL. 34,
L21707,
doi:10.1029/2007GL030547,
2007
Amount-weighted annual isotopic (δ18O) values are affected by the seasonality of precipitation: A sensitivity study
R. W. Vachon
Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA
J. W. C. White
Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA
E. Gutmann
Center for the Study of Earth from Space and Cooperative Institute for Research in Environmental Science, University of Colorado,
Boulder, Colorado, USA
J. M. Welker
Environment and Natural Resources Institute and Biology Department, University of Alaska Anchorage, Alaska, USA
Abstract
Year to year differences in the isotopes of precipitation (δ 18O) are typically attributed to corresponding interannual changes in mean annual temperature. However, changes in the seasonal
distribution of precipitation are one of the main complicating factors in interpreting year to year variability of isotopes
of precipitation. Using a five year dataset with 73 sites across the United States, we investigate the influence of changes
in seasonal distribution of precipitation on annually averaged δ 18O. Based on these δ 18O measurements, and using multi-decadal records of variability of monthly precipitation amounts, we identify areas within
the United States where records of isotopes in precipitation are susceptible to changes in the seasonal distribution of precipitation.
For the three regions, Northern Great Plains, the Rocky Mountains, and the Southwest, seasonality effects could be misinterpreted
as 1°C to 3°C temperature changes between years. These findings will improve and possibly change our interpretation of climate
isotopic climate records and provide spatially explicit areas where classic interpretations require caution.
Received 1
May
2007;
accepted 8
October
2007;
published 15
November
2007.
Keywords: precipitation;
stable isotopes;
climate change.
Index Terms: 1041 Geochemistry: Stable isotope geochemistry (0454, 4870); 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513); 3354 Atmospheric Processes: Precipitation (1854); 3344 Atmospheric Processes: Paleoclimatology (0473, 4900); 3333 Atmospheric Processes: Model calibration (1846).
Read Full Article (file size: 313059 bytes) Cited by
Citation: Vachon, R. W., J. W. C. White, E. Gutmann, and J. M. Welker
(2007),
Amount-weighted annual isotopic (δ18O) values are affected by the seasonality of precipitation: A sensitivity study,
Geophys. Res. Lett.,
34,
L21707,
doi:10.1029/2007GL030547.
Copyright 2007 by the American Geophysical Union.
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