Recreating the California New Year's Flood Event of 1997 in a Regionally Refined Earth System Model

Rhoades, Alan M.; Zarzycki, Colin M.; Inda‐Diaz, Héctor A.; Ombadi, Mohammed; Pasquier, Ulysse; Srivastava, Abhishekh; Hatchett, Benjamin J.; Dennis, Eli; Heggli, Anne; McCrary, Rachel; McGinnis, Seth; Rahimi‐Esfarjani, Stefan; Slinskey, Emily; Ullrich, Paul A.; Wehner, Michael; Jones, Andrew D.

doi:10.1029/2023ms003793

Cited by 8 publications

(10 citation statements)

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“…To simulate the 1997 flood, we employ the U.S. Department of Energy-funded Energy Exascale Earth System Model (E3SM) version 2 (Golaz et al, 2022;Tang et al, 2022;Harrop et al, 2023). To ensure that the 1997 flood event hydrometeorological characteristics are skillfully recreated, we leverage the regionally refined mesh capabilities of E3SM (RRM-E3SM) at 3.5km horizontal resolution centered over California (Rhoades et al, 2023). The RRM-E3SM simulations are simulated using Atmosphere Model Intercomparison Project (AMIP) protocols (Gates et al, 1999) whereby the atmospheric (E3SM Atmosphere Model; EAM) and land surface (E3SM Land Model; ELM) sub-component models of E3SM are two-way coupled and lower boundary sea surface temperatures and sea ice conditions are prescribed.…”

Section: Methodsmentioning

confidence: 99%

“…A detailed explanation of the RRM-E3SM (3.5km) model experimental setups (e.g., dynamical core choice, subgrid-scale parameterization schemes, etc.) are provided in Rhoades et al (2023).…”

Section: Methodsmentioning

confidence: 99%

“…We acknowledge a small amount of warming occurred between 1850 and 1920 (approximately +0.1°C; see Figure 2 of Kay et al [2015]), however, we opt to use the pre-industrial naming convention to maintain consistency with Pettett and Zarzycki (2023). We simulate the 1997 flood under the observed atmospheric, land and oceanic conditions in 1997, called the "control" simulation (Rhoades et al, 2023). Then, we simulate the 1997 flood event under "contemporary" atmospheric and oceanic conditions where the CESM-LENS ensemble average reaches a global-mean value of +1°C of warming (in 2019) relative to 1920 in the atmosphere over both the ocean and land.…”

Section: Methodsmentioning

confidence: 99%

“…The New Year's flood event of 1997, hereafter referred to as the 1997 flood, is an object lesson (or case study) of a RoS event that had substantial societal implications in both California and Nevada (Tarouilly et al, 2021). The 1997 flood featured land surface preconditioning (e.g., saturated soils and accumulation of an above normal snowpack, even at lower elevations, following an extremely wet November-December) and a strong landfalling AR event that elevated freezing levels to nearly 3000 m, and resulted in widespread snowmelt following prolonged rainfall (Rhoades et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

“…In Rhoades et al (2023), we simulated the 1997 flood "event that was" as realistically as possible. This study identified that the regionally refined mesh capabilities of the Energy Exascale Earth System Model (RRM-E3SM) with the appropriate horizontal resolution and forecast lead time is fit-for-purpose to recreate several of the major hydrometeorological drivers of the 1997 flood.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Anticipating How Rain-on-Snow Events Will Change through the 21st Century: Lessons from the 1997 New Year’s Flood Event

Rhoades,

Zarzycki,

Hatchett

et al. 2024

Preprint

Self Cite

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The California-Nevada 1997 New Year’s flood was an atmospheric river (AR)-driven rain-on-snow (RoS) event and remains the costliest in their history. The joint occurrence of saturated soils, rainfall, and snowmelt generated inundation throughout northern California-Nevada. Although AR RoS events are projected to occur more frequently with climate change, the warming sensitivity of their flood drivers across scales remains understudied. We leverage the regionally refined mesh capabilities of the Energy Exascale Earth System Model (RRM-E3SM) to recreate the 1997 New Year’s flood at a horizontal resolution of 3.5km across California, with forecast lead times of 2-4 days, and across six warming levels ranging from pre-industrial conditions to +3.5\degree{}C. We describe the sensitivity of the 1997 flood drivers to warming including AR duration and intensity, precipitation phase, intensity and efficiency, snowpack mass and energy changes, and runoff efficiency. Our findings indicate current levels of climate change negligibly influence the 1997 flood. At warming levels ≥1.7°C, AR hazard potential increases, snowpack nonlinearly decreases, antecedent soil moisture decreases (except where the snowline retreats), and runoff decreases (except in the southern Sierra Nevada where antecedent snowpack persists). Storm total precipitation increases, but at rates below warming-induced increases in saturation-specific humidity. Warming intensifies short-duration, high-intensity rainfall, particularly where snowfall-to-rainfall transitions occur. This study highlights the nonlinear tradeoffs in 21st-century RoS flood hazards with warming and provides water management and infrastructure investment adaptation considerations.

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Section: Methodsmentioning

confidence: 99%

“…A detailed explanation of the RRM-E3SM (3.5km) model experimental setups (e.g., dynamical core choice, subgrid-scale parameterization schemes, etc.) are provided in Rhoades et al (2023).…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Anticipating How Rain-on-Snow Events Will Change through the 21st Century: Lessons from the 1997 New Year’s Flood Event

Rhoades,

Zarzycki,

Hatchett

et al. 2024

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

Anticipating how rain-on-snow events will change through the 21st century: lessons from the 1997 new year’s flood event

Rhoades,

Zarzycki,

Hatchett

et al. 2024

Clim Dyn

View full text Add to dashboard Cite

The California-Nevada 1997 New Year’s flood was an atmospheric river (AR)-driven rain-on-snow (RoS) event and remains the costliest in their history. The joint occurrence of saturated soils, rainfall, and snowmelt generated inundation throughout northern California-Nevada. Although AR RoS events are projected to occur more frequently with climate change, the warming sensitivity of their flood drivers across scales remains understudied. We leverage the regionally refined mesh capabilities of the Energy Exascale Earth System Model (RRM-E3SM) to recreate the 1997 New Year’s flood with horizontal grid spacings of 3.5 km across California, with forecast lead times of up to 4 days, and across six warming levels ranging from pre-industrial conditions to $$+3.5\,^\circ$$ + 3.5 ∘ C. We describe the sensitivity of the flood drivers to warming including AR duration and intensity, precipitation phase, intensity and efficiency, snowpack mass and energy changes, and runoff efficiency. Our findings indicate current levels of climate change negligibly influence the flood drivers. At warming levels $$\ge 1.7\,^\circ$$ ≥ 1.7 ∘ C, AR hazard potential increases, snowpack nonlinearly decreases, antecedent soil moisture decreases (except where the snowline retreats), and runoff decreases (except in the southern Sierra Nevada where antecedent snowpack persists). Storm total precipitation increases, but at rates below warming-induced increases in saturation-specific humidity. Warming intensifies short-duration, high-intensity rainfall, particularly where snowfall-to-rainfall transitions occur. This study highlights the nonlinear tradeoffs in 21st-century RoS flood hazards with warming and provides water management and infrastructure investment adaptation considerations.

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Reinterpreting ENSO's Role in Modulating Impactful Precipitation Events in California

Guirguis,

Hatchett,

Gershunov

et al. 2024

Geophysical Research Letters

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Water years (WY) 2017 and 2023 were anomalously wet for California, each alleviating multiyear drought. In both cases, this was unexpected given La Niña conditions, with most seasonal forecasts favoring drier‐than‐normal winters. We analyze over seven decades of precipitation and snow records along with mid‐tropospheric circulation to identify recurring weather patterns driving California precipitation and Sierra Nevada snowpack. Tropical forcing by ENSO causes subtle but important differences in these wet weather patterns, which largely drives the canonical seasonal ENSO‐precipitation relationship. However, the seasonal frequency of these weather patterns is not strongly modulated by ENSO and remains a primary source of uncertainty for seasonal forecasting. Seasonal frequency of ENSO‐independent weather patterns was a major cause of anomalous precipitation in WY2017, record‐setting snow in WY2023, and differences in precipitation outcome during recent El Niño winters 1983, 1998, and 2016. Improved understanding of recurrent atmospheric weather patterns could help to improve seasonal precipitation forecasts.

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Recreating the California New Year's Flood Event of 1997 in a Regionally Refined Earth System Model

Cited by 8 publications

References 125 publications

Anticipating How Rain-on-Snow Events Will Change through the 21st Century: Lessons from the 1997 New Year’s Flood Event

Anticipating How Rain-on-Snow Events Will Change through the 21st Century: Lessons from the 1997 New Year’s Flood Event

Anticipating how rain-on-snow events will change through the 21st century: lessons from the 1997 new year’s flood event

Reinterpreting ENSO's Role in Modulating Impactful Precipitation Events in California

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