Atmospheric Rivers, Version 1

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.