Representation of Atmospheric Water Budget and Uncertainty Quantification of Future Changes in CMIP6 for the Seven U.S. National Climate Assessment Regions

Agniv Sengupta, Duane E. Waliser, Elias C. Massoud, Bin Guan, Colin Raymond, Huikyo Lee

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Observation-based climate model evaluation and future projections help policymakers in developing action plans for efficient management of water resources and mitigation of the impacts of hazardous extremes. Apart from this socioeconomic importance, the scientific value cannot be overstated, especially in light of the upcoming Fifth U.S. National Climate Assessment (NCA) report. In this study, we evaluate the realism of hydroclimate variability in the historical simulations of a suite of coupled general circulation models (CGCMs) participating in the fifth and sixth phases of the Coupled Model Intercomparison Project (CMIP5 and CMIP6). Our results demonstrate systematic biases in the simulated seasonal precipitation-most prominently, wet bias over the mountainous western United States in winter, and dry bias over the U.S. central plains in summer. A distinctive feature of this work is our focus on the examination of the atmospheric water budget, in particular the relative importance of remote and local contributions-convergence of moisture fluxes and local land surface processes (evapotranspiration) respectively-in helping produce precipitation. This diagnosis reveals that the leading contribution of the remote influence in winter is overestimated by the CMIP6 multimodel mean (MMM), whereas the local influence, which is more influential in summer, is underestimated. Our results aid in understanding the drivers of seasonal precipitation over the United States, where precipitation will likely increase by the end of the century but with significant model disagreement for the summer and fall. In support of ongoing NCA efforts, our study aims to contribute a comprehensive, regional-level analysis of the moisture budget and emphasizes the importance of realistically simulating its major components in CGCMs.

Original languageEnglish
Pages (from-to)3635-3658
Number of pages24
JournalJournal of Climate
Volume35
Issue number22
DOIs
StatePublished - Nov 15 2022

Funding

Acknowledgments. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. We acknowledge the climate modeling groups for making their model outputs available, the Program for Climate Model Diagnosis and Intercomparison for collecting and archiving CMIP data, and WCRP’s Working Group on Coupled Modelling. A.S. would like to thank Dr. Alfredo Ruiz-Barradas for his help with providing the topography and bathymetry data.

Keywords

  • Climate models
  • Model evaluation/performance
  • Water budget/balance

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