HR: 1340h
AN: H33E-1424    [Abstracts]
TI: Hydrogen and Oxygen Isotope Data From the AIRMoN Sampling Network, Central and Eastern USA, Suggest a High Degree of Short-Term Isotopic Variability in Precipitation
AU: * Sjostrom, D J
EM: ands3@uaa.alaska.edu
AF: Environmental and Natural Resources Institute, University of Alaska Anchorage, 707 A St., Anchorage, AK 99501 United States
AU: Welker, J M
EM: afjmw1@uaa.alaska.edu
AF: Environmental and Natural Resources Institute, University of Alaska Anchorage, 707 A St., Anchorage, AK 99501 United States
AB: The Atmospheric Integrated Research Monitoring Network (AIRMoN) deposition program consists of an array of precipitation collection stations located throughout the eastern and central United States. At these locations, daily to sub-weekly precipitation sample collection has resulted in an extensive archive of precipitation that allows for analysis on the scale of individual precipitation events. Approximately 500 of these samples collected during 1996-2000 from Florida, Illinois, Ohio, Tennessee, Vermont, and West Virginia have been analyzed for delta D and delta 18 O in order to assess the short-term variability of the isotopic composition of precipitation. The isotopic composition of samples among precipitation events from all locations is highly variable. For example, delta values range by as much as approximately 100 per mil for hydrogen and approximately 12 per mil for oxygen for precipitation events separated by only a few days regardless of geographic location and time of year. There is a weak correlation between temperature at the time of the precipitation event and isotopic value of precipitation at all locations. In general, the long-established trends in isotopic values at different geographic locations are evident in this dataset. For example, on average, the most depleted isotopic values are from locations in the northern and eastern part of the study area, and the most enriched values are from the low latitude sample sites. For individual precipitation events throughout the study area, however, storm source appears to be the primary control of isotopic value rather than temperature. The database that will result from the ongoing isotopic analysis of the complete suite of AIRMoN samples will allow for the examination of both short (daily) and long (decadal) timescale oxygen and hydrogen isotope composition over a wide area of the United States. This dataset will be of benefit to (for example) the study of geographic extent and influence of El Nino/La Nina cycles and other sub-annual to and decadal scale modifications to atmospheric circulation, the back-calculation of storm trajectories, and the temporal variability of climate that may not be evident from traditional climate studies.
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1836 Hydrological cycles and budgets (1218, 1655)
DE: 1848 Monitoring networks
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
SC: Hydrology [H]
MN: Fall Meeting 2005