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    • Atmospheric Rivers, Version 1

    Metadata Updated: December 12, 2025

    The Atmospheric Rivers, Version 1 (AR V1) is a historical record of ARs and related fields based on the ERA5 Reanalysis. The data is regional in coverage (Western U.S.), high resolution in both space (~31 km) and time (6 h), and covers a long period of record (1940-present). It uses the AR scale to broadly characterizes the strength of ARs using categorical rankings from 1-5 based on the peak integrated water vapor transport (IVT) and duration of AR conditions (i.e., IVT > 250 kg m-1 s-1) at a given location. Since the AR scale does not account for object geometry, it detects some events associated with strong and persistent IVT that are not considered ARs (e.g., tropical storms and Monsoon surges). This is considered to be the "unfiltered" version of the data. In addition, a "filtered" version of the data set uses "tARget v3", a well-known AR detection tool (ARDT) that utilizes various climatological, geometric, and directional thresholds to identify ARs, to "filter" out most non-AR events - this allows events detected using the scale, from category 1-5, to be differentiated between ARs and other event types.

    Access & Use Information

    License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

    Downloads & Resources

    Dates

    Metadata Date July 24, 2025
    Metadata Created Date December 12, 2025
    Metadata Updated Date December 12, 2025
    Reference Date(s) December 1, 2024 (publication)
    Frequency Of Update monthly

    Metadata Source

    Harvested from ncdc

    Other Data Resources

    Graphic Preview

    "Filtered" AR Scale Value for Landfalling AR

    Additional Metadata

    Resource Type Dataset
    Metadata Date July 24, 2025
    Metadata Created Date December 12, 2025
    Metadata Updated Date December 12, 2025
    Reference Date(s) December 1, 2024 (publication)
    Responsible Party NOAA National Centers for Environmental Information (Point of Contact)
    Contact Email
    Guid gov.noaa.ncdc:C01714
    Access Constraints Cite as: Rutz, J. J., E. A. Slinskey, and B. Guan. 2024. Atmospheric Rivers, Version 1 .[indicate subset used]. NOAA National Centers for Environmental Information. https://doi.org/10.25921/tkq4-xj93 . Accessed [date]., Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives., Use liability: NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose.
    Bbox East Long -105.0
    Bbox North Lat 52.0
    Bbox South Lat 25.0
    Bbox West Long -135.0
    Coupled Resource
    Frequency Of Update monthly
    Graphic Preview Description "Filtered" AR Scale Value for Landfalling AR
    Graphic Preview File https://www.ncei.noaa.gov/pub/data/metadata/images/C01714.png
    Graphic Preview Type PNG
    Harvest Object Id 3523d20c-d0bd-46cc-b165-bdf1a08aabf9
    Harvest Source Id 2cb3ef77-1683-4c2a-9119-dc65e50917c6
    Harvest Source Title ncdc
    Licence The data set is based on the AR scale, for which 250 units of IVT is the lowest threshold (category 1). This works very well over lower-elevation areas of the Western U.S. where the background moisture field it quite dry. However, even the "filtered" version of the data identifies various phenomena (e.g., pressure gradient-driven low-level jets) as ARs over the eastern U.S. and other regions globally, whereas many canonical process associated with ARs are not present. In addition, the CDR has progressively limited utility over higher elevations regions, as 250 units of IVT becomes climatologically more difficult to achieve with decreasing depth of the atmospheric column.
    Lineage
    Metadata Language eng; USA
    Metadata Type geospatial
    Old Spatial {"type": "Polygon", "coordinates": [[[-135.0, 25.0], [-105.0, 25.0], [-105.0, 52.0], [-135.0, 52.0], [-135.0, 25.0]]]}
    Progress onGoing
    Spatial Data Service Type
    Spatial Reference System
    Spatial Harvester True
    Temporal Extent Begin 1940
    Temporal Extent End 2024-10-30

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