On the evolution of moisture sources through the deglaciation

Abstract:

During the deglaciation, the hydrologic cycle underwent significant shifts owing to the large changes topographic forcing, greenhouse gas concentration, and orbital forcing. Water isotopologues record these shifts, but the interpretation is complicated because multiple factors – including temperature changes, precipitation changes, humidity changes, and vapor source distribution changes – influence the final composition.

Here we utilize the Goddard Institute for Space Studies general circulation model (GISS-E2) to simulate deglacial changes in water isotopes (Ullman et al, 2014). We then utilize boundary conditions from the coupled model to drive atmospheric-only simulations that incorporate a separate and complementary suite of tracers called vapor source distribution tracers to identify shifts in moisture sources at key locations for paleoclimate archives.

We find large modulations in moisture convergences, vapor source distributions, as well as temperature and precipitation happening in parallel with the water isotopologue changes. We offer some preliminary insight into the drivers of isotopologue changes in the GISS-E2 model through the deglation.