Title: Future Projections of the Large-Scale Meteorology Associated with California Heat Waves in CMIP5 Models

Abstract

Abstract Previous work showed that climate models capture historical large‐scale meteorological patterns (LSMPs) associated with California Central Valley heat waves including both ways these heat waves form. This work examines what models predict under the Representative Concentration Pathway (RCP) 4.5 and RCP8.5 scenarios. Model performance varies, so a multimodel average weights each model based on its historical performance in four parameters. An LSMP index (LSMPi) defined using upper atmosphere variables captures dates of past extreme surface temperature maxima. LSMPi correlates well with all values of California Central Valley‐average surface maximum temperature. LSMPi distributions in future simulations shift ~0.6 standard deviations higher between 1961–2000 and 2061–2100 for RCP8.5 data. Based on the historical climatology, future scenarios show a large increase in the frequency and duration of heat waves in every model. Four times as many heat waves occur and their median duration doubles, using historical thresholds. Of the two ways heat waves form, Type 1 has similar frequency in the future. But, Type 2 becomes much more common because Type 2 has a preexisting hot anomaly in Southwestern Canada, much like the historical to future climatological change in that region (a “global warming” signal). The 20‐year return value anomaly increases bymore » 30–40%. The average of the 50 hottest temperatures increases 3.5–6 K depending on the scenario. When extreme values are defined using the future climatology, the models and their average have no consistent increase or decrease of distribution properties such as shape, scale, and return values of the extremes compared to historical values.« less

Authors:

Palipane, Erool  ^[1];

• Search DOE PAGES for author "Palipane, Erool"
• Search DOE PAGES for ORCID "0000-0003-4482-6106"

Grotjahn, Richard  ^[1]

• Search DOE PAGES for author "Grotjahn, Richard"
• Search DOE PAGES for ORCID "0000-0003-0918-0215"

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+ Show Author Affiliations

1. Univ. of California, Davis, CA (United States)

Publication Date:

Sat Jul 28 00:00:00 EDT 2018

Research Org.:

Univ. of California, Davis, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1539764

Alternate Identifier(s):

OSTI ID: 1465893

Grant/Contract Number:  

SC0016605

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research: Atmospheres

Additional Journal Information:

Journal Volume: 123; Journal Issue: 16; Journal ID: ISSN 2169-897X

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; Meteorology & Atmospheric Sciences