Publication Abstracts

Baek et al. 2020, in press

Baek, S.H., J.E. Smerdon, B.I. Cook, and A.P. Williams, 2020: US Pacific coastal droughts are predominantly driven by internal atmospheric variability. J. Climate, in press, doi:10.1175/JCLI-D-20-0365.1.

Droughts that span the states of Washington, Oregon, and California are rare but devastating due to their large spatial coverage and potential loss of redundancies in water, agricultural, and fire-fighting resources. Such pan-coastal droughts (which we define using boreal summer volumetric soil moisture along the US Pacific coast (32-50°N; 115-127°W)) require a more precise understanding of the roles played by the Pacific Ocean and internal atmospheric variability. We employ 16-member ensembles of the Community Atmosphere Model 5 and Community Climate Model 3 forced with observed sea surface temperatures (SSTs) from 1856-2012 to explicitly separate and quantify the influences of the tropical Pacific and internal atmospheric variability on pan-coastal droughts; all other boundary conditions are kept at climatological levels to explicitly isolate for the impacts of SST changes. Internal atmospheric variability is the dominant driver of pan-coastal droughts, accounting for 84% of their severity and can reliably generate pan-coastal droughts even when ocean conditions do not favor drought. Cold phases of the Pacific Ocean play a secondary role and contribute, on average, only 16% to pan-coastal drought severity. Spatiotemporal analyses of precipitation and soil moisture along the US Pacific coast corroborate these findings and identify an anti-phased, wet/dry dipole pattern induced by the Pacific to play a more secondary role. Our model framework expands on previous observational analyses that point to the spatially uniform forcing of internal atmospheric variability as the more dominant mode of hydroclimate variability along the US Pacific coast. The secondary nature of oceanic forcing suggests limited predictability of pan-continental droughts.

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BibTeX Citation

@unpublished{ba09600r,
  author={Baek, S. H. and Smerdon, J. E. and Cook, B. I. and Williams, A. P.},
  title={US Pacific coastal droughts are predominantly driven by internal atmospheric variability},
  year={2020},
  journal={J. Climate},
  doi={10.1175/JCLI-D-20-0365.1},
  note={Manuscript accepted for publication}
}

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RIS Citation

TY  - INPR
ID  - ba09600r
AU  - Baek, S. H.
AU  - Smerdon, J. E.
AU  - Cook, B. I.
AU  - Williams, A. P.
PY  - 2020
TI  - US Pacific coastal droughts are predominantly driven by internal atmospheric variability
JA  - J. Climate
DO  - 10.1175/JCLI-D-20-0365.1
ER  -

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