Poulsen, Cody D., Clemesha, Rachel E. S., Howard, Ian M., Gershunov, Alexander, Dettinger, Micheal D., Zhang, Zhenhai, Luna-Niño, Rosa, Stahle, David W., Ralph, F. Martin (2025). Data from: The 1991 California "Miracle March": Precipitation Myth or Miracle?. UC San Diego Library Digital Collections. https://doi.org/10.6075/J0DR2VRQ

This object contains the data and code necessary to reproduce the plots and analysis for "The 1991 California “Miracle March”: Precipitation Myth or Miracle?", published in Environmental Research Communications by Poulsen et al. (2025). The gridded precipitation data sets used in this study and included in this collection are from the PRISM Climate Group at Oregon State University. The Livneh daily precipitation data set used for Figure 3 is from NOAA PSL. The geopotential height and wind data are from NCEP/NCAR. The vertically integrated vapor transport (IVT) data set was computed by the Center for Western Weather and Water Extremes (CW3E) using NASA data (MERRA-2). All data is publicly available from the institutions listed, and citations for data sets are located in the "Data availability statement" at the end of the manuscript.

In California, water year 1991 was characterized by heavy precipitation in March, following one of the driest winters on record, lessening the burden of drought entering the dry season. The methods used to analyze the data in this collection can be viewed in the code included (Python and R) and act as a model to work with this data to analyze the climate context and impacts of extreme precipitation events on seasonal totals. All of the data sets in this collection are in the NetCDF file format. The data files and scripts are organized into collection components based on data type and named respectively as Python code, Precipitation data, Geopotential height and wind data, Vertically-integrated water vapor transport (IVT) data, and Figure 3 data. The Readme file provides greater details on the files located in each collection component.

• 1900 to 2023

• 2025

• Clemesha, Rachel E. S.
• Dettinger, Micheal D.
• Gershunov, Alexander
• Howard, Ian M.
• Luna-Niño, Rosa
• Poulsen, Cody D.
• Stahle, David W.
• Zhang, Zhenhai

• Ralph, F. Martin

This work is funded by the California Department of Water Resources, Atmospheric River Program Phase IV (contract number 4600014942). This research also contributes to the Department of the Interior Southwest Climate Adaptation Science Center, which is managed by the USGS National Climate Adaptation Science Center.

• California
• Western North America

• Atmospheric rivers (AR)
• Daily precipitation
• Domain: Environmental sciences
• Monthly precipitation
• Precipitation extremes
• Subdomain: Environmental management
• Vertically integrated vapor transport (IVT)

• data
• software

• English

Identifier: Alexander Gershunov: https://orcid.org/0000-0002-6598-6638

Identifier: Cody D. Poulsen: https://orcid.org/0009-0001-7680-6620

Identifier: Ian M. Howard: https://orcid.org/0000-0002-8361-9575

Identifier: Micheal D. Dettinger: https://orcid.org/0000-0002-7509-7332

Identifier: Rachel E. S. Clemesha: https://orcid.org/0000-0002-3881-2384

Identifier: Rosa Luna-Niño: https://orcid.org/0000-0003-3679-6410

Identifier: Zhenhai Zhang: https://orcid.org/0000-0001-8459-4704

Primary associated publication

• Poulsen, Cody D., Clemesha, Rachel E. S., Howard, Ian M., Gershunov, Alexander, Dettinger, Michael D., Zhang, Zhenhai, Luna-Niño, Rosa, Stahle, David W., Ralph, F. Martin (2025). The 1991 California “Miracle March”: Precipitation Myth or Miracle?. Environmental Research Communications.

Creative Commons Attribution 4.0 International Public License

• UC Regents

Under copyright (US)

Use: This work is available from the UC San Diego Library. This digital copy of the work is intended to support research, teaching, and private study.

Constraint(s) on Use: This work is protected by the U.S. Copyright Law (Title 17, U.S.C.). Use of this work beyond that allowed by "fair use" or any license applied to this work requires written permission of the copyright holder(s). Responsibility for obtaining permissions and any use and distribution of this work rests exclusively with the user and not the UC San Diego Library. Inquiries can be made to the UC San Diego Library program having custody of the work.

Research Data Curation Program, UC San Diego, La Jolla, 92093-0175 (https://lib.ucsd.edu/rdcp)

2025-04-30