Response of atmospheric river width and intensity to aquaplanet warming: A detection algorithm- and background moisture-independent approach

The width of an atmospheric river (AR) is an important parameter when
evaluating its impact. Although previous research suggests ARs will widen
with global warming, a precise response has been muddled by the large
sensitivity of width to a diverse set of AR detection techniques (ARDTs).
Here we propose a methodology that removes the influence of the ARDT by
modeling AR integrated vapor transport (IVT) profiles as idealized
exponential curves with free parameters given by background IVT, intensity
above background IVT, and profile width. Notably, our definition for AR
profile width does not include any explicit numerical thresholds, relative
or absolute, for IVT. We apply our approach to a series of idealized
aquaplanet experiments, first with a baseline sea-surface temperature
(SST) distribution, then with +2K, +4K and +6K uniform warming, so as to
determine the contributions of each free parameter to AR width. We also
apply our approach to high resolution atmosphere-only models forced with
SSTs modified to preserve historical variability but following projected
warming over 2016-2050. Our results show that contributions to
impacts-relevant AR widening comes primarily from enhancements in
background IVT and AR intensity, as opposed to from dynamic width
changes. This dataset provides data needed to reproduce the
results of this study.