Grand challenges in asian summer monsoon modeling - representation of processes and sources of model error

H. Annamalai, William R. Boos, Gill Martin, Brian Mapes, Yi Ming, P. Mukhopadhyay, Tieh Yong Koh, Suryachandra Rao

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Simulating the monsoon precipitation climatology in climate models remains a grand challenge. Multi-model-mean (MMM) errors for the Asian-Australian Monsoon (AAM) precipitation climatology have shown little improvement in 7 years (from CMIP3 to CMIP5), relative to observations. Bias in future projections of seasonal-mean AAM rainfall may therefore, logically, also not have been reduced. Might there be fundamental limits to realistically simulating the AAM? Or can a concerted observational and modeling effort enhance the fidelity of models in simulating the monsoon? The persistence of model errors suggests that they are not easy to fix, perhaps arising from multiple processes and their interactions. However, the constancy of their spatial pattern may suggest a robust source of error, perhaps in model numerics (e.g., treatments of topography at coarse resolution) or in a fundamental assumption behind physical parameterizations (such as convection) that, perhaps, persists because of a lack of detailed observations to constrain model physics. A systematic effort on this problem would require, but might also serve to foster, a better understanding of the interacting dynamic, thermodynamic, orographic, and oceanographic processes that shape the monsoon precipitation climatology, and the representation of these processes in climate models. Toward these goals, members of the CLIVAR-GEWEX Working Group on the Asian-Australian monsoons have diagnosed processes in CMIP3/5 models, performed idealized numerical experiments with coupled and uncoupled models, and identified a few possible sources of model errors. In this paper, we present key results from these recent studies and discuss how errors in one variable cascade into others. For improved process representation and monsoon simulation, we stress the need for coordinated efforts including focused process-based diagnostics and high-quality observations to constrain model physics.

Original languageEnglish (US)
Title of host publicationMultiscale Global Monsoon System, The
PublisherWorld Scientific Publishing Co.
Pages367-386
Number of pages20
ISBN (Electronic)9789811216602
DOIs
StatePublished - Jan 4 2021
Externally publishedYes

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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