Climate Dynamics

, Volume 41, Issue 2, pp 403–420

Winter precipitation isotope slopes of the contiguous USA and their relationship to the Pacific/North American (PNA) pattern

  • Zhongfang Liu
  • Gabriel J. Bowen
  • Jeffrey M. Welker
  • Kei Yoshimura
Article

DOI: 10.1007/s00382-012-1548-0

Cite this article as:
Liu, Z., Bowen, G.J., Welker, J.M. et al. Clim Dyn (2013) 41: 403. doi:10.1007/s00382-012-1548-0

Abstract

This study compares the synoptic-dynamic relationship between two phases of the Pacific/North American (PNA) pattern and winter precipitation isotopes at 73 sites across the contiguous USA. We use the spatial pattern of isotope slope—the rate of changes in precipitation isotope ratios with distance—to identify features in the seasonal precipitation isotope fields related to climatic patterns, PNA positive and PNA negative. Our results show relationships between zones of high isotope slopes and the spatial position of the polar jet stream and juxtaposition of air masses associated with the PNA pattern. During a positive PNA winter, zones of high isotope slope in the eastern USA shift southward. This change is coincident with a southward displacement of the polar jet stream in this region, which leads to a greater frequency of polar air masses and 18O-depleted isotope values of precipitation in the region. In the western USA, zones of high slope shift eastward during the positive PNA winter, associated with more frequent penetration of tropical air masses that bring 18O-enriched precipitation to the region. Differences in δ18O/temperature relationships between the PNA-positive and -negative winters and contrasting δ18O/temperature behaviors in the eastern and western USA provide support for the role of variation in moisture source and transport as a control on the isotopic patterns. These findings highlight the importance of synoptic climate driven by PNA pattern in determining the spatial patterns of precipitation isotopes and provide constraints on paleo-water isotope interpretation and modern isotope hydrological processes.

Keywords

Precipitation isotope slope Pacific/North American Atmospheric circulation 

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Zhongfang Liu
    • 1
    • 5
  • Gabriel J. Bowen
    • 2
    • 6
  • Jeffrey M. Welker
    • 3
    • 4
  • Kei Yoshimura
    • 5
  1. 1.Tianjin Key Laboratory of Water Resource and EnvironmentTianjin Normal UniversityTianjinChina
  2. 2.Department of Earth and Atmospheric SciencesPurdue UniversityWest LafayetteUSA
  3. 3.Environment and Natural Resources InstituteUniversity of Alaska AnchorageAnchorageUSA
  4. 4.Department of Biological SciencesUniversity of Alaska AnchorageAnchorageUSA
  5. 5.Atmosphere and Ocean Research InstituteUniversity of TokyoKashiwaJapan
  6. 6.Department of Geology and GeophysicsUniversity of UtahSalt Lake CityUSA