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Observed impacts of duration and seasonality of atmospheric-river landfalls on soil moisture and runoff in coastal northern California

Journal of Hydrometeorology

By:
, , , , and
DOI: 10.1175/JHM-D-12-076.1

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Abstract

This study is motivated by diverse needs for better forecasts of extreme precipitation and floods. It is enabled by unique hourly observations collected over six years near California’s Russian River and by recent advances in the science of atmospheric rivers (ARs). This study fills key gaps limiting the prediction of ARs and, especially, their impacts by quantifying the duration of AR conditions and the role of duration in modulating hydrometeorological impacts. Precursor soil moisture conditions and their relationship to streamflow are also shown. On the basis of 91 well-observed events during 2004-10, the study shows that the passage of ARs over a coastal site lasted 20 h on average and that 12% of the AR events exceeded 30 h. Differences in storm-total water vapor transport directed up the mountain slope contribute 74% of the variance in storm-total rainfall across the events and 61% of the variance in storm-total runoff volume. ARs with double the composite mean duration produced nearly 6 times greater peak streamflow and more than 7 times the storm-total runoff volume. When precursor soil moisture was less than 20%, even heavy rainfall did not lead to significant streamflow. Predicting which AR events are likely to produce extreme impacts on precipitation and runoff requires accurate prediction of AR duration at landfall and observations of precursor soil moisture conditions.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Observed impacts of duration and seasonality of atmospheric-river landfalls on soil moisture and runoff in coastal northern California
Series title:
Journal of Hydrometeorology
DOI:
10.1175/JHM-D-12-076.1
Volume
14
Issue:
2
Year Published:
2013
Language:
English
Publisher:
American Meteorological Society
Contributing office(s):
Branch of Regional Research-Western Region
Description:
17 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Hydrometeorology
First page:
443
Last page:
459
Country:
United States
State:
California