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

Journal Article · 11 October 2023 · Journal of Advances in Modeling Earth Systems

DOI: https://doi.org/10.1029/2023MS003793 · OSTI ID:2067660

Rhoades, Alan M.  ^[1]; Zarzycki, Colin M.  ^[2]; Inda‐Diaz, Héctor A.  ^[1]; Ombadi, Mohammed  ^[3]; Pasquier, Ulysse  ^[1]; Srivastava, Abhishekh  ^[4]; Hatchett, Benjamin J.  ^[5]; Dennis, Eli  ^[6]; Heggli, Anne ^[5]; McCrary, Rachel ^[7]; McGinnis, Seth  ^[7]; Rahimi‐Esfarjani, Stefan  ^[6]; Slinskey, Emily  ^[6]; Ullrich, Paul A.  ^[8]; Wehner, Michael  ^[9]; Jones, Andrew D.  ^[10]

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1. Lawrence Berkeley National Laboratory Earth and Environmental Sciences Area Berkeley CA USA
2. Department of Meteorology and Atmospheric Science Penn State University State College PA USA
3. Lawrence Berkeley National Laboratory Earth and Environmental Sciences Area Berkeley CA USA, Department of Climate and Space Sciences and Engineering University of Michigan Ann Arbor MI USA
4. Department of Land, Air, and Water Resources University of California Davis CA USA
5. Desert Research Institute Reno NV USA
6. Institute of the Environment and Sustainability University of California, Los Angeles Los Angeles CA USA
7. National Center for Atmospheric Research Boulder CO USA
8. Lawrence Berkeley National Laboratory Earth and Environmental Sciences Area Berkeley CA USA, Department of Land, Air, and Water Resources University of California Davis CA USA, Lawrence Livermore National Laboratory Physical and Life Sciences Directorate Livermore CA USA
9. Computational Sciences Division Lawrence Berkeley National Laboratory Berkeley CA USA
10. Lawrence Berkeley National Laboratory Earth and Environmental Sciences Area Berkeley CA USA, Energy and Resources Group University of California, Berkeley Berkeley CA USA

Abstract The 1997 New Year's flood event was the most costly in California's history. This compound extreme event was driven by a category 5 atmospheric river that led to widespread snowmelt. Extreme precipitation, snowmelt, and saturated soils produced heavy runoff causing widespread inundation in the Sacramento Valley. This study recreates the 1997 flood using the Regionally Refined Mesh capabilities of the Energy Exascale Earth System Model (RRM‐E3SM) under prescribed ocean conditions. Understanding the processes causing extreme events informs practical efforts to anticipate and prepare for such events in the future, and also provides a rich context to evaluate model skill in representing extremes. Three California‐focused RRM grids, with horizontal resolution refinement of 14 km down to 3.5 km, and six forecast lead times, 28 December 1996 at 00Z through 30 December 1996 at 12Z, are assessed for their ability to recreate the 1997 flood. Planetary to synoptic scale atmospheric circulations and integrated vapor transport are weakly influenced by horizontal resolution refinement over California. Topography and mesoscale circulations, such as the Sierra barrier jet, are better represented at finer horizontal resolutions resulting in better estimates of storm total precipitation and storm duration snowpack changes. Traditional time‐series and causal analysis frameworks are used to examine runoff sensitivities state‐wide and above major reservoirs. These frameworks show that horizontal resolution plays a more prominent role in shaping reservoir inflows, namely the magnitude and time‐series shape, than forecast lead time, 2‐to‐4 days prior to the 1997 flood onset.

• Sponsoring Organization: USDOE
• Grant/Contract Number: NONE; SC0016605; AC02-05CH11231
• OSTI ID: 2067660
• Alternate ID(s): OSTI ID: 2067661; OSTI ID: 2228590
• Journal Information: Journal of Advances in Modeling Earth Systems, Journal Name: Journal of Advances in Modeling Earth Systems Journal Issue: 10 Vol. 15; ISSN 1942-2466
• Publisher: American Geophysical Union (AGU)Copyright Statement
• Country of Publication: United States
• Language: English