Application of a Semi-Lagrangian Advection Scheme for Transport of Stable Water Isotopes Over the Antarctic Plateau in the Isotope-Incorporated Global Spectral Model (IsoGSM)

Stable water isotopes have unique physical characteristics and are therefore key in research on paleoclimate proxies and Earth's hydrological cycle. Isotope-incorporated General Circulation Models (GCMs) are powerful tools that account for the physical processes related to stable water isotopes. In this study, we implemented a global version of the Non-iteration Dimensional-split Semi-Lagrangian (NDSL) advection scheme in the IsoGSM to address a systematic bias in the delta values of surface precipitation over the Antarctic Plateau during austral winter (June–July–August; JJA). Results indicate that the spatial distribution of delta deuterium of surface precipitation during austral summer (December–January–February; DJF) is accurately simulated by both the control experiment (CNTL) and a subsequent NDSL experiment (NDSLQ); however, during austral winter, CNTL and NDSLQ exhibit differences, particularly over East Antarctica. Notably, NDSLQ captures the temperature effect more effectively than CNTL. Analysis of precipitation systems crossing the Korean Peninsula reveals that NDSLQ produces a much more realistic distribution of water vapor than that of CNTL, impacting not only the overall upward motion throughout the troposphere but also the position and intensity of surface precipitation. Overall, we recommend using a global spectral model with the NDSL advection scheme instead of the spectral method to improve the simulation of stable water isotopes over Antarctica and weather systems at mid-latitudes.