Exploring Western North Pacific Tropical Cyclone Activity in the High‐Resolution Community Atmosphere Model

Journal Article · 29 December 2021 · Earth and Space Science

DOI: https://doi.org/10.1029/2021EA001862 · OSTI ID:1837775

Wu, Xiaoning  ^[1]; Reed, Kevin A.  ^[1]; Callaghan, Patrick  ^[2]; Bacmeister, Julio T.  ^[2]

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1. School of Marine and Atmospheric Sciences Stony Brook University Stony Brook NY USA
2. Climate and Global Dynamics Laboratory National Center for Atmospheric Research Boulder CO USA

Abstract High‐resolution climate models (∼28 km grid spacing) can permit realistic simulations of tropical cyclones (TCs), thus enabling their investigation in relation to the climate system. On the global scale, previous works have demonstrated that the Community Atmosphere Model (CAM) version 5 presents a reasonable TC climatology under prescribed present‐day (1980–2005) forcing. However, for the Western North Pacific (WNP) region, known biases in simulated TC genesis frequency and location under‐represent the basin's dominant share in observations. This study addresses these model biases in WNP by evaluating WNP TCs in a decadal simulation, and exploring potential improvements through nudging experiments. Among the major environmental controls of TC genesis, the lack of mid‐level moisture is identified as the leading cause of the deficit in simulated WNP TC genesis over the Pacific Warm Pool. Subsequent seasonal experiments explore the effect of constraining the large‐scale environment on TC development by nudging WNP temperature field toward reanalysis at various strengths. Temperature nudging elicits a significant response in TC genesis and intensity development, as well as in moisture and convection over the Warm Pool. These responses are sensitive to the choice of nudging timescale. Overall, the nudging experiments demonstrate that improvements in the large‐scale environment can lead to improvements in simulated TCs, suggesting future model developments in relation to model physics. In this way, the potential improvements in model fidelity will contribute to the understanding of how the mean state of current or future climates may give rise to extremes such as TCs.

• Research Organization: Stony Brook University, NY (United States)
• Sponsoring Organization: National Center for Atmospheric Research; National Science Foundation (NSF); USDOE; USDOE Office of Science (SC)
• Grant/Contract Number: SC0016605; SC0019459
• OSTI ID: 1837775
• Journal Information: Earth and Space Science, Journal Name: Earth and Space Science Journal Issue: 1 Vol. 9; ISSN 2333-5084
• Publisher: American Geophysical Union (AGU)Copyright Statement
• Country of Publication: United States
• Language: English