IVT thresholds used by version 2 of the Brands algorithm:

Grid-point IVT must exceed the following relative thresholds:

1. 90th percentile at the point of AR detection
2. 85th percentile along the AR structure

and the following absolute thresholds:

3. 500 kg m-1 s-1 at the point of AR detection
4. 250 kg m-1 s-1 along the AR structure

Length criterion: 1500 km
Width criterion: None

NOTE: Percentiles are calculate separately for each grid box,
considering the time period 1981-2010 - all months are taken
into account.

More details on the method can be found in:

Brands S, Gutiérrez JM, San-Martín D (2017): Twentieth-century
atmospheric river activity along the west coasts of Europe and western
North America: algorithm formulation, reanalysis uncertainty and links 
to atmospheric circulation patterns. Climate Dynamics 48(9-10), 2771-
2795, doi: 10.1007/s00382-016-3095-6

Based on this algorithm, an AR archive has been built for western North
American and Europe, covering 1900-2014:

http://www.meteo.unican.es/atmospheric-rivers

Contact: swen.brands@gmail.com