Forecasting the Hydroclimatic Signature of the 2015/16 El Niño Event on the Western United States

Wanders, Niko; Bachas, A.; He, Xiao-Gang; Huang, Huilin; Koppa, Akash; Mekonnen, Z. T.; Pagán, Brianna R.; Peng, Liqing; Vergopolan, Noemi; Wang, K. J.; Xiao, Mu; Zhan, Shengan; Lettenmaier, Dennis P.; Wood, Eric F.

doi:10.1175/jhm-d-16-0230.1

Cited by 31 publications

(29 citation statements)

References 17 publications

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“…The operational seasonal climate prediction models from the North American Multi-Model Ensemble (NMME) (Kirtman et al 2014) successfully predicted the tropical Pacific SST aspects of this extreme El Niño event months in advance. However, the models predicted a canonical El Niño precipitation pattern with wet conditions over Southern California, thus failing to predict the observed precipitation anomalies over WUS (Wanders et al 2017). In contrast, the observed precipitation anomalies during the winter of the other most recent major El Niño in 1997/98 largely resembled the typical pattern over the WUS (Fig.…”

Section: Introductionmentioning

confidence: 85%

On the seasonal prediction of the western United States El Niño precipitation pattern during the 2015/16 winter

et al. 2018

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A "typical" El Niño leads to wet (dry) wintertime anomalies over the southern (northern) half of the Western United States (WUS). However, during the strong El Niño of 2015/16, the WUS winter precipitation pattern was roughly opposite to this canonical (average of the record) anomaly pattern. To understand why this happened, and whether it was predictable, we use a suite of high-resolution seasonal prediction experiments with coupled climate models. We find that the unusual 2015/16 precipitation pattern was predictable at zero-lead time horizon when the ocean/atmosphere/land components were initialized with observations. However, when the ocean alone is initialized the coupled model fails to predict the 2015/16 pattern, although ocean initial conditions alone can reproduce the observed WUS precipitation during the 1997/98 strong El Niño. Further observational analysis shows that the amplitudes of the El Niño induced tropical circulation anomalies during 2015/16 were weakened by about 50% relative to those of 1997/98. This was caused by relative cold (warm) anomalies in the eastern (western) tropical Pacific suppressing (enhancing) deep convection anomalies in the eastern (western) tropical Pacific during 2015/16. The reduced El Niño teleconnection led to a weakening of the subtropical westerly jet over the southeast North Pacific and southern WUS, resulting in the unusual 2015/16 winter precipitation pattern over the WUS. This study highlights the importance of initial conditions not only in the ocean, but in the land and atmosphere as well, for predicting the unusual El Niño teleconnection and its influence on the winter WUS precipitation anomalies during 2015/16.

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Section: Introductionmentioning

confidence: 85%

On the seasonal prediction of the western United States El Niño precipitation pattern during the 2015/16 winter

et al. 2018

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“…El Niño suggests warming may be influencing predictability of associated climate effects, perhaps via changes in atmospheric circulation (Seager, Naik, & Vecchi, 2010;Singh et al, 2016;Wanders et al, 2017).…”

Section: Niña Periodsmentioning

confidence: 99%

“…Failure of flipped models to predict growth during distinctly different time periods (LNP vs OY) demonstrates that models parameterized for different ENSO phases are not interchangeable, and capture distinct growth responses to climate. Changes in ENSO influences on winter precipitation could also arise with warming and changes in global or regional atmospheric circulation (Singh et al, 2016;Wanders et al, 2017). In the NAM region, winter precipitation deficits associated with La Niña years result in drought legacies and increased reliance on monsoonal precipitation, particularly for species growing at low and mid-elevations (e.g., P. edulis and P. ponderosa).…”

Section: Niña Periods Across the Nam Regionmentioning

confidence: 99%

“…Though southern populations in the Southwest may exhibit the most variable growth responses, delayed monsoon arrival would likely have particularly severe consequences for these populations following La Niña winters, as monsoonal precipitation plays a key role in drought recovery. Changes in ENSO influences on winter precipitation could also arise with warming and changes in global or regional atmospheric circulation (Singh et al, 2016;Wanders et al, 2017). Widespread mortality events suggest conditions may already be exceeding the resilience capacity in these systems (Allen et al, 2010).…”

Section: Niña Periods Across the Nam Regionmentioning

confidence: 99%

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Legacies of La Niña: North American monsoon can rescue trees from winter drought

Peltier

Ogle

2018

Global Change Biology

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While we often assume tree growth–climate relationships are time‐invariant, impacts of climate phenomena such as the El Niño Southern Oscillation (ENSO) and the North American Monsoon (NAM) may challenge this assumption. To test this assumption, we grouped ring widths (1900‐present) in three southwestern US conifers into La Niña periods (LNP) and other years (OY). The 4 years following each La Niña year are included in LNP, and despite 1–2 year growth declines, compensatory adjustments in tree growth responses result in essentially equal mean growth in LNP and OY, as average growth exceeds OY means 2–4 years after La Niña events. We found this arises because growth responses in the two periods are not interchangeable: Due to differences in growth–climate sensitivities and climatic memory, parameters representing LNP growth fail to predict OY growth and vice versa (decreases in R2 up to 0.63; lowest R2 = 0.06). Temporal relationships between growth and antecedent climate (memory) show warmer springs and longer growing seasons negatively impact growth following dry La Niña winters, but that NAM moisture can rescue trees after these events. Increased importance of monsoonal precipitation during LNP is key, as the largest La Niña‐related precipitation deficits and monsoonal precipitation contributions both occur in the southern part of the region. Decreases in first order autocorrelation during LNP were largest in the heart of the monsoon region, reflecting both the greatest initial growth declines and the largest recovery. Understanding the unique climatic controls on growth in Southwest conifers requires consideration of both the influences and interactions of drought, ENSO, and NAM, each of which is likely to change with continued warming. While plasticity of growth sensitivity and memory has allowed relatively quick recovery in the tree‐ring record, recent widespread mortality events suggest conditions may soon exceed the capacity for adjustment in current populations.

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“…Recent development of vine copulas (pair-copula constructions) can overcome these limitations as it can decompose the multivariate copulas into pair copulas based on hierarchical graphical models (Bedford and Cooke 2002;Kurowicka and Cooke 2006;Cooke et al 2015). Given these advantages, the vine copula has been widely applied in hydrology recently (e.g., Hao and Singh 2016;Wanders et al 2017;Bevacqua et al 2017). In this study, we utilized the R package VineCopula to optimize the vine structure (either C-vine or D-vine) through the determination of the most appropriate bivariate copula family and its corresponding parameters (see details in Schepsmeier et al 2012).…”

Section: E530mentioning

confidence: 99%

A Global Drought and Flood Catalogue from 1950 to 2016

Pan

Wei

et al. 2020

Bulletin of the American Meteorological Society

121

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Hydrological extremes, in the form of droughts and floods, have impacts on a wide range of sectors including water availability, food security, and energy production. Given continuing large impacts of droughts and floods and the expectation for significant regional changes projected in the future, there is an urgent need to provide estimates of past events and their future risk, globally. However, current estimates of hydrological extremes are not robust and accurate enough, due to lack of long-term data records, standardized methods for event identification, geographical inconsistencies, and data uncertainties. To tackle these challenges, this article presents the development of the first Global Drought and Flood Catalogue (GDFC) for 1950–2016 by merging the latest in situ and remote sensing datasets with state-of-the-art land surface and hydrodynamic modeling to provide a continuous and consistent estimate of the terrestrial water cycle and its extremes. This GDFC also includes an unprecedented level of detailed analysis of drought and large-scale flood events using univariate and multivariate risk assessment frameworks, which incorporates regional spatial–temporal characteristics (i.e., duration, spatial extent, severity) and global hazard maps for different return periods. This Catalogue forms a basis for analyzing the changing risk of droughts and floods and can underscore national and international climate change assessments and provide a key reference for climate change studies and climate model evaluations. It also contributes to the growing interests in multivariate and compounding risk analysis.

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Forecasting the Hydroclimatic Signature of the 2015/16 El Niño Event on the Western United States

Cited by 31 publications

References 17 publications

On the seasonal prediction of the western United States El Niño precipitation pattern during the 2015/16 winter

On the seasonal prediction of the western United States El Niño precipitation pattern during the 2015/16 winter

Legacies of La Niña: North American monsoon can rescue trees from winter drought

A Global Drought and Flood Catalogue from 1950 to 2016

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