Intraseasonal variation of the summer rainfall over the Southeastern United States
© 2018 Springer-Verlag GmbH Germany, part of Springer Nature This study characterizes the intraseasonal variability (ISV) in the Southeastern United States (SE US) rainfall in boreal summer and delineates the associated dynamical processes featuring three-way interactions among the SE US rainfall, t...
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ftdukeunivdsp:oai:localhost:10161/17796 2023-11-12T04:22:46+01:00 Intraseasonal variation of the summer rainfall over the Southeastern United States Wei, Wei Li, Wenhong Deng, Yi Yang, Song 2018-12-18T15:39:36Z application/pdf https://hdl.handle.net/10161/17796 en eng Springer Nature America, Inc Climate Dynamics 10.1007/s00382-018-4345-6 0930-7575 1432-0894 https://hdl.handle.net/10161/17796 Journal article 2018 ftdukeunivdsp 2023-10-17T09:40:38Z © 2018 Springer-Verlag GmbH Germany, part of Springer Nature This study characterizes the intraseasonal variability (ISV) in the Southeastern United States (SE US) rainfall in boreal summer and delineates the associated dynamical processes featuring three-way interactions among the SE US rainfall, the central US low-level jet (LLJ), and the North Atlantic subtropical high (NASH). The analysis reveals that the ISV of the SE summer rainfall peaks at the 10‒20-day timescales. The physical mechanisms for the three-way interactions on the 10‒20-day timescales are proposed. When the NASH attains a minimum strength, the reduced size of the NASH is accompanied with an eastward retreat of the western ridge of the NASH, leading to a decrease in the zonal pressure gradient and consequently a weakening of the LLJ 1 day after. The weakened LLJ and the eastward-shifted NASH western ridge induces anomalous cyclonic circulation over the SE US, moves preferred regions of moisture convergence from central US to the SE US, and 3 days later the SE US rainfall attains its maximum strength. The excessive latent heating associated with the enhanced SE US rainfall excites an anomalous anticyclone northeast of the rainfall region, resulting in an increase in the NASH intensity that peaks 2 days after the maximum SE US rainfall. The NASH subsequently expands with its western ridge moving westward, zonal pressure gradient restored, and LLJ strength recovered. An anomalous anticyclone then emerges over the SE US and suppresses rainfall, marking the shift from an intraseasonal wet phase to dry phase in this region. A more rigorous proof of these causalities demand carefully designed numerical experiments and further statistical analysis in future. Our results suggest that improved prediction of SE US summer rainfall across intraseasonal scales depends critically on the model representation of the three-way coupling among the NASH, the central US LLJ, and the SE US rainfall. Article in Journal/Newspaper North Atlantic Duke University Libraries: DukeSpace Nash ENVELOPE(-62.350,-62.350,-74.233,-74.233) |
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English |
description |
© 2018 Springer-Verlag GmbH Germany, part of Springer Nature This study characterizes the intraseasonal variability (ISV) in the Southeastern United States (SE US) rainfall in boreal summer and delineates the associated dynamical processes featuring three-way interactions among the SE US rainfall, the central US low-level jet (LLJ), and the North Atlantic subtropical high (NASH). The analysis reveals that the ISV of the SE summer rainfall peaks at the 10‒20-day timescales. The physical mechanisms for the three-way interactions on the 10‒20-day timescales are proposed. When the NASH attains a minimum strength, the reduced size of the NASH is accompanied with an eastward retreat of the western ridge of the NASH, leading to a decrease in the zonal pressure gradient and consequently a weakening of the LLJ 1 day after. The weakened LLJ and the eastward-shifted NASH western ridge induces anomalous cyclonic circulation over the SE US, moves preferred regions of moisture convergence from central US to the SE US, and 3 days later the SE US rainfall attains its maximum strength. The excessive latent heating associated with the enhanced SE US rainfall excites an anomalous anticyclone northeast of the rainfall region, resulting in an increase in the NASH intensity that peaks 2 days after the maximum SE US rainfall. The NASH subsequently expands with its western ridge moving westward, zonal pressure gradient restored, and LLJ strength recovered. An anomalous anticyclone then emerges over the SE US and suppresses rainfall, marking the shift from an intraseasonal wet phase to dry phase in this region. A more rigorous proof of these causalities demand carefully designed numerical experiments and further statistical analysis in future. Our results suggest that improved prediction of SE US summer rainfall across intraseasonal scales depends critically on the model representation of the three-way coupling among the NASH, the central US LLJ, and the SE US rainfall. |
format |
Article in Journal/Newspaper |
author |
Wei, Wei Li, Wenhong Deng, Yi Yang, Song |
spellingShingle |
Wei, Wei Li, Wenhong Deng, Yi Yang, Song Intraseasonal variation of the summer rainfall over the Southeastern United States |
author_facet |
Wei, Wei Li, Wenhong Deng, Yi Yang, Song |
author_sort |
Wei, Wei |
title |
Intraseasonal variation of the summer rainfall over the Southeastern United States |
title_short |
Intraseasonal variation of the summer rainfall over the Southeastern United States |
title_full |
Intraseasonal variation of the summer rainfall over the Southeastern United States |
title_fullStr |
Intraseasonal variation of the summer rainfall over the Southeastern United States |
title_full_unstemmed |
Intraseasonal variation of the summer rainfall over the Southeastern United States |
title_sort |
intraseasonal variation of the summer rainfall over the southeastern united states |
publisher |
Springer Nature America, Inc |
publishDate |
2018 |
url |
https://hdl.handle.net/10161/17796 |
long_lat |
ENVELOPE(-62.350,-62.350,-74.233,-74.233) |
geographic |
Nash |
geographic_facet |
Nash |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
Climate Dynamics 10.1007/s00382-018-4345-6 0930-7575 1432-0894 https://hdl.handle.net/10161/17796 |
_version_ |
1782337702764478464 |