Teleconnections Governing the Interannual Variability of Great Plains Low-Level Jets in May.
In: Journal of Climate, Jg. 34 (2021-06-15), Heft 12, S. 4785-4802
Online
academicJournal
Zugriff:
A spectral analysis of Great Plains 850-hPa meridional winds (V850) from ECMWF's coupled climate reanalysis of 1901–2010 (CERA-20C) reveals that their warm season (April–September) interannual variability peaks in May with 2–6-yr periodicity, suggestive of an underlying teleconnection influence on low-level jets (LLJs). Using an objective, dynamical jet classification framework based on 500-hPa wave activity, we pursue a large-scale teleconnection hypothesis separately for LLJs that are uncoupled (LLJUC) and coupled (LLJC) to the upper-level jet stream. Differentiating between jet types enables isolation of their respective sources of variability. In the U.S. south-central plains (SCP), May LLJCs account for nearly 1.6 times more precipitation and 1.5 times greater V850 compared to LLJUCs. Composite analyses of May 250-hPa geopotential height (Z250) conditioned on LLJC and LLJUC frequencies highlight a distinct planetary-scale Rossby wave pattern with wavenumber 5, indicative of an underlying circumglobal teleconnection (CGT). An index of May CGT is found to be significantly correlated with both LLJC (r = 0.62) and LLJUC (r = −0.48) frequencies. Additionally, a significant correlation is found between May LLJUC frequency and NAO (r = 0.33). Further analyses expose decadal-scale variations in the CGT–LLJC and CGT–LLJUC teleconnections that are linked to the PDO. Dynamically, these large-scale teleconnections impact LLJ class frequency and intensity via upper-level geopotential anomalies over the western United States that modulate near-surface geopotential and temperature gradients across the SCP. [ABSTRACT FROM AUTHOR]
Titel: |
Teleconnections Governing the Interannual Variability of Great Plains Low-Level Jets in May.
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Autor/in / Beteiligte Person: | Agrawal, Shubhi ; Ferguson, Craig R. ; Bosart, Lance ; Burrows, D. Alex |
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Zeitschrift: | Journal of Climate, Jg. 34 (2021-06-15), Heft 12, S. 4785-4802 |
Veröffentlichung: | 2021 |
Medientyp: | academicJournal |
ISSN: | 0894-8755 (print) |
DOI: | 10.1175/JCLI-D-20-0451.1 |
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