Published In

Journal of Climate

Document Type

Article

Publication Date

8-1-2022

Subjects

Numerical weather forecasting, Climatology, Synoptic climatology, Atmospheric waves

Abstract

Projected changes in atmospheric ridges and associated temperature and precipitation anomalies are assessed for the end of the twenty-first century in a suite of 27 models contributing to phase 6 of the Coupled Model Intercomparison Project (CMIP6) under a high-end emissions scenario over the Pacific–North American region. Ridges are defined as spatially coherent regions of positive zonal anomalies in 500-hPa geopotential height. The frequency of ridge days in the historical period varies by geography and season; however, ridge days are broadly more common over the region in winter and least common in summer. The CMIP6 models are credible in reproducing key features of reanalysis-derived ridge climatology. The CMIP6 models also reproduce historical temperature and precipitation anomalies associated with ridges. These associations include positive temperature anomalies over and to the west/northwest of the ridge peak and negative precipitation anomalies southeast of the ridge peak. Future projections show a general decrease in ridge days across most of the region in fall through spring, with considerable model agreement. Projections for summer are different, with robust projections of increases in the number of ridge days across parts of the interior western United States and Canada. The CMIP6 models project modest decreases in the probability of stronger ridges and modest increases in the probability of weaker ridges in fall and winter. Future ridges show similar temperature and precipitation anomaly associations as in the historical climate period, when future anomalies are computed relative to future climatology.

Rights

© 2022 American Meteorological Society (AMS). For permission to reuse any portion of this Work, please contact permissions@ametsoc.org. Any use of material in this Work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act (17 U.S. Code § 107) or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC § 108) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. All AMS journals and monograph publications are registered with the Copyright Clearance Center (https://www.copyright.com). Additional details are provided in the AMS Copyright Policy statement, available on the AMS website (https://www.ametsoc.org/PUBSCopyrightPolicy).

DOI

10.1175/JCLI-D-21-0794.1

Persistent Identifier

https://archives.pdx.edu/ds/psu/38385

Available for download on Wednesday, February 01, 2023

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