TITLE:

INVESTIGATING THE SOURCE ORIGIN OF ATMOSPHERIC MOISTURE USING STABLE ISOTOPE OBSERVATION AND MODELING

DATE:

Friday, Oct 26th, 2012

TIME:

3:30 PM

LOCATION:

GMCS 214

SPEAKER:

Chun-Ta Lai.
Department of Biology.
San Diego State University.

ABSTRACT:

The stable isotope composition of water can be used to identify conditions and pathways
under which water exchange occurs between global reservoirs. The fundamental
mechanism involves the preferential removal of light nuclides during evaporation and
heavy nuclides during condensation. For example, the isotopic composition of vapor
released from an evaporating surface has lower contents in heavy oxygen (d18O) and
hydrogen (d2H) compared to its source water. Atmospheric transport and synoptic
weather circulation has been shown to strongly influence the isotope composition of
precipitation and atmospheric moisture measured in continental locations. Continental
water vapor is also subject to the influence of evapotranspirational fluxes. Isotope
enabled GCMs were developed to investigate forcing mechanisms in the water cycle
that alter water vapor isotopologues, and in turn, to inform climate models of the
atmospheric and hydrologic processes that act as the primary control of moisture sources,
transport and distribution. A critical component to the knowledge gained from these
modeling exercises resides in the realism of model simulation when compared to actual
observations. In this talk, I will explain the fundamental atmospheric and hydrologic
processes that govern the isotope variation in the meteoric water using case studies
coupling isotope measurements and modeling.

HOST:

Dr. Jose Castillo.

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