HR: 12:05h
AN: B41E-08    [PDF]
TI: Climate Phase and Long-Term Site Specific Patterns of Isotopes (d18O) in Precipitation across the U. S.
AU: * Welker, J M
EM: jwelker@nrel.colostate.edu
AF: Natural Resource Ecology Lab, Colorado State University, Fort Collins, CO 80523 United States
AU: White, J W
EM: jwhite@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80345 United States
AU: Vachon, R
EM: ryan.vachon@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80345 United States
AU: Zauscher, M
EM: melaine@gandulazul.com
AF: Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80345 United States
AU: Castro, C
EM: chris@atmos.colostate.edu
AF: Department of Atmospheric Sciences, Colorado State University, Fort Collins, CO 80523 United States
AU: Pielke, R
EM: pielke@atmos.colostate.edu
AF: Department of Atmospheric Sciences, Colorado State University, Fort Collins, CO 80523 United States
AB: Our understanding of the spatial and temporal patterns of the isotopic characteristics of precipitation across the U. S. has been limited because no systematic analysis have been conducted across the U. S. during divergent climate phases or over extended recent time periods. Using weekly precipitation samples from a spatially complete set of sampling stations across the U. S. we have evaluate the following questions: a) what are the seasonal patterns of the isotopic (d18O) patterns across the U. S. during Neutral and El Nino phases, b) to what degree do differences in temperature, precipitation and climatology explain El Nino affects on the seasonal patterns of isotopes in precipitation and c) what are the long-term patterns and magnitudes of d18O-values in precipitation over a recent 10-year period for sites in the western, central and eastern U. S.? We have found that depleted precipitation dominates the Northern Rocky Mountain region, while relatively enriched precipitation occurs in the western U. S. and in the southern Great Lakes region, however, these patterns are season specific, being magnified in spring and fall. These seasonal differences appear to reflect climatological changes with intensification of the sub-tropical flow and a delay in the monsoon formation during El Nino phases. Time-series data for sites in the western U. S. exhibit the strongest annual and monthly temperature correlations with slopes ranging between 0.3 to 0.6oC per mil of d18O.
DE: 1040 Isotopic composition/chemistry
DE: 1655 Water cycles (1836)
DE: 1854 Precipitation (3354)
DE: 3309 Climatology (1620)
DE: 4522 El Ni¤o
SC: Biogeosciences [B]
MN: 2003 Fall Meeting