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The Full Extent of El Niño's Precipitation Influence on the United States and the Americas: The Suboptimality of the Niño 3.4 SST Index
Author(s) -
Nigam Sumant,
Sengupta Agniv
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl091447
Subject(s) - precipitation , climatology , index (typography) , spring (device) , environmental science , la niña , atmospheric sciences , geography , geology , el niño southern oscillation , meteorology , physics , world wide web , computer science , thermodynamics
Key features of El Niño's influence on North American winter precipitation are well‐known but we show that this influence has, hitherto, been suboptimally characterized in winter, and especially in fall and spring. The suboptimality has arisen from the historical over‐reliance on regressions on the Niño 3.4 SST index—a widely used marker of El Niño variability. We show that El Niño's full influence is obtained from assembling the regressions on the spatiotemporal modes constituting El Niño variability, rather than from regressions on an SST index keyed just to its mature phase (Niño 3.4 index). The notably different influence of central and eastern Pacific El Niños on Eastern Seaboard is documented. The full influence of El Niño on North American precipitation is shown to be substantially larger than previously recognized and pronounced not just in northern winter but even in fall and spring—enhancing prospects for year‐round seasonal prediction.