TY - JOUR
T1 - Changes in atmospheric rivers and moisture transport over the Northeast Pacific and western North America in response to ENSO diversity
AU - Kim, Hye Mi
AU - Zhou, Yang
AU - Alexander, Michael A.
N1 - Funding Information:
Constructive and valuable comments from Dr. Matthew Newman (NOAA/ESRL) and two anonymous reviewers are greatly appreciated. The authors would like to thank Mr. Lequan Chi for helping with the AR detection coding. This study was supported by NOAA’s CPO MAPP under Grant NA15OAR4310078 and the KMA R&D Program under Grant KMIPA 2016–6010.
Funding Information:
Acknowledgements Constructive and valuable comments from Dr. Matthew Newman (NOAA/ESRL) and two anonymous reviewers are greatly appreciated. The authors would like to thank Mr. Lequan Chi for helping with the AR detection coding. This study was supported by NOAA’s CPO MAPP under Grant NA15OAR4310078 and the KMA R&D Program under Grant KMIPA 2016–6010.
Publisher Copyright:
© 2017, Springer-Verlag Berlin Heidelberg.
PY - 2019/6/1
Y1 - 2019/6/1
N2 - The year-to-year changes in atmospheric rivers (ARs) and moisture transport over the northeast Pacific and western North America are investigated during December to February (DJF) from 1979/80 to 2015/16. Changes in AR frequency, intensity, and landfall characteristics are compared between three ENSO phases: central Pacific El Niño (CPEN), eastern Pacific El Niño (EPEN), and La Niña (NINA). During EPEN events, the subtropical jet extends to the south and east with an anomalous cyclonic flow around a deeper Aleutian Low. More moisture is transported towards North America and AR frequency is increased over western North America. In CPEN events, the Aleutian low shifts further southward relative to its position in EPEN, resulting in an increase in the frequency and intensity of landfalling ARs over the southwestern US. In NINA events, the landfalling AR frequency is reduced associated with anomalous anticyclonic circulation over the eastern North Pacific. We diagnose the contribution of multiple factors to the seasonal mean moisture transport using moisture budgets. During the three ENSO phases, the change in low-frequency circulation (dynamical process) is the leading contributor to the seasonal mean moisture flux divergence, while the contributions of the synoptic anomalies and the change in moisture anomaly (thermodynamic process) are not significant along the west coast of North America.
AB - The year-to-year changes in atmospheric rivers (ARs) and moisture transport over the northeast Pacific and western North America are investigated during December to February (DJF) from 1979/80 to 2015/16. Changes in AR frequency, intensity, and landfall characteristics are compared between three ENSO phases: central Pacific El Niño (CPEN), eastern Pacific El Niño (EPEN), and La Niña (NINA). During EPEN events, the subtropical jet extends to the south and east with an anomalous cyclonic flow around a deeper Aleutian Low. More moisture is transported towards North America and AR frequency is increased over western North America. In CPEN events, the Aleutian low shifts further southward relative to its position in EPEN, resulting in an increase in the frequency and intensity of landfalling ARs over the southwestern US. In NINA events, the landfalling AR frequency is reduced associated with anomalous anticyclonic circulation over the eastern North Pacific. We diagnose the contribution of multiple factors to the seasonal mean moisture transport using moisture budgets. During the three ENSO phases, the change in low-frequency circulation (dynamical process) is the leading contributor to the seasonal mean moisture flux divergence, while the contributions of the synoptic anomalies and the change in moisture anomaly (thermodynamic process) are not significant along the west coast of North America.
UR - http://www.scopus.com/inward/record.url?scp=85015635669&partnerID=8YFLogxK
U2 - 10.1007/s00382-017-3598-9
DO - 10.1007/s00382-017-3598-9
M3 - Article
AN - SCOPUS:85015635669
SN - 0930-7575
VL - 52
SP - 7375
EP - 7388
JO - Climate Dynamics
JF - Climate Dynamics
IS - 12
ER -