skip to main content

Title: Measurements of 18 O 18 O and 17 O 18 O in the atmosphere and the role of isotope-exchange reactions: 18 O 18 O AND 17 O 18 O IN THE ATMOSPHERE
; ;
Award ID(s):
Publication Date:
Journal Name:
Journal of Geophysical Research: Atmospheres
Page Range or eLocation-ID:
n/a to n/a
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    The isotopic composition of precipitation is used to trace water cycling and climate change, but interpretations of the environmental information recorded in central Andean precipitation isotope ratios are hindered by a lack of multi‐year records, poor spatial distribution of observations, and a predominant focus on Rayleigh distillation. To better understand isotopic variability in central Andean precipitation, we present a three‐year record of semimonthly δ18Opand δ2Hpvalues from 15 stations in southern Peru and triple oxygen isotope data, expressed as ∆′17Op, from 32 precipitation samples. Consistent with previous work, we find that elevation correlates negatively with δ18Opand that seasonal δ18Opvariations are related to upstream rainout and local convection. Spatial δ18Opvariations and atmospheric back trajectories show that both eastern‐ and western‐derived air masses bring precipitation to southern Peru. Seasonal d‐excesspcycles record moisture recycling and relative humidity at remote moisture sources, and both d‐excesspand ∆′17Opclearly differentiate evaporated and non‐evaporated samples. These results begin to establish the natural range of unevaporated ∆′17Opvalues in the central Andes and set the foundation for future paleoclimate and paleoaltimetry studies in the region. This study highlights the hydrologic understanding that comes from a combination of δ18Op, d‐excessp, and ∆′17Opdata and helps identify the evaporation, recycling, and rainout processesmore »that drive water cycling in the central Andes.

    « less