DOI: 10.5061/dryad.wstqjq2zb
title: Response of atmospheric river width and intensity to aquaplanet warming: A detection algorithm- and background moisture-independent approach

description: 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.
description: # Response of atmospheric river width and intensity to aquaplanet warming:
 A detection algorithm- and background moisture-independent approach This
 dataset provides integrated vapor transport (IVT) and TempestExtremes
 catalogs for (i) the CESM2 uniform warming experiments and (ii) the
 CMCC-CM2-VHR4 and MPI-ESM1-2-HR highresSST experiments. Integrated water
 vapor is also included for the CESM2 experiments. The data provided here
 accompany (and can be used to reproduce) the results of the
 above-mentioned study. Brief descriptions of model experiments are
 provided below: The CESM2 model is run under an aquaplanet configuration
 at 3-hourly time resolution. The aquaplanet has no land, sea, ice,
 topography, or axial tilt (i.e., perpetual equinox conditions), and
 features a single-layer “data ocean” which thermally forces the atmosphere
 with fixed sea surface temperatures (SSTs). Specifically, we use the
 “QOBS” profile from Neale and Hoskins (2000), while the warming scenarios
 feature globally uniform SST increases of +2 K, +4 K, and +6 K,
 respectively. Each respective SST experiment (Baseline, +2K, +4, and +6K)
 is run for 31 months. We examine "highresSST" experiments of the
 High Resolution Model Intercomparison Project (HighResMIP) at 6-hourly
 resolution, focusing on outputs from the CMCC-CM2-VHR4 and MPI-ESM1-2-HR
 models. The experiments force CMCC-CM2-VHR4 and MPI-ESM1-2-HR models with
 modified HadISST2.2 that preserve historical variability but follow RCP8.5
 warming over 2016-2050. We analyze ARs and IVT from the two models over
 the North Pacific to better facilitate comparisons to aquaplanet
 experiments, focusing specifically on two 31-month intervals: (i)
 06/01/2008 to 12/31/2010; and (ii) 06/01/2048 to 12/31/2050. ###
 Description of the data and file structure Files are provided as .nc
 files. A brief description of the files are provided: *
 spinears_plus0K.nc: TempestExtreme spine AR tags for the CESM2 +0K
 experiment. * spinears_plus2K.nc: TempestExtreme spine AR tags for the
 CESM2 +2K experiment. * spinears_plus4K.nc: TempestExtreme spine AR tags
 for the CESM2 +4K experiment. * spinears_plus6K.nc: TempestExtreme spine
 AR tags for the CESM2 +6K experiment. * IVTx_plus0K.nc: IVTx for the CESM2
 +0K experiment. * IVTx_plus2K.nc: IVTx for the CESM2 +2K experiment. *
 IVTx_plus4K.nc: IVTx for the CESM2 +4K experiment. * IVTx_plus6K.nc: IVTx
 for the CESM2 +6K experiment. * IVTy_plus0K.nc: IVTy for the CESM2 +0K
 experiment. * IVTy_plus2K.nc: IVTy for the CESM2 +2K experiment. *
 IVTy_plus4K.nc: IVTy for the CESM2 +4K experiment. * IVTy_plus6K.nc: IVTy
 for the CESM2 +6K experiment. * IWV_plus0K.nc: Integrated water vapor for
 the CESM2 +0K experiment. * IWV_plus2K.nc: Integrated water vapor for the
 CESM2 +2K experiment. * IWV_plus4K.nc: Integrated water vapor for the
 CESM2 +4K experiment. * IWV_plus6K.nc: Integrated water vapor for the
 CESM2 +6K experiment. * TE_spinears_MPI-ESM1-2-HR_20080601-20101231.nc:
 TempestExtreme spine AR tags for the MPI-ESM1-2-HR highresSST experiment
 over 06/01/2008 to 12/31/2010. *
 TE_spinears_MPI-ESM1-2-HR_20480601-20501231.nc: TempestExtreme spine AR
 tags for the MPI-ESM1-2-HR highresSST experiment over 06/01/2048 to
 12/31/2050. * IVT_MPI-ESM1-2-HR_20080601-20101231.nc: IVT for the
 MPI-ESM1-2-HR highresSST experiment over 06/01/2008 to 12/31/2010. *
 IVT_MPI-ESM1-2-HR_20480601-20501231.nc: IVT for the MPI-ESM1-2-HR
 highresSST experiment over 06/01/2048 to 12/31/2050. *
 TE_spinears_CMCC-CM2-VHR4_20080601-20101231.nc: TempestExtreme spine AR
 tags for the CMCC-CM2-VHR4 highresSST experiment over 06/01/2008 to
 12/31/2010. * TE_spinears_CMCC-CM2-VHR4_20480601-20501231.nc:
 TempestExtreme spine AR tags for the CMCC-CM2-VHR4 highresSST experiment
 over 06/01/2048 to 12/31/2050. * IVT_CMCC-CM2-VHR4_20080601-20101231.nc:
 IVT for the CMCC-CM2-VHR4 highresSST experiment over 06/01/2008 to
 12/31/2010. * IVT_CMCC-CM2-VHR4_20480601-20501231.nc: IVT for the
 CMCC-CM2-VHR4 highresSST experiment over 06/01/2048 to 12/31/2050. ###
 Sharing/Access information The CESM2 experiments were generated by
 University of California, Davis. The highresSST experiments, including SST
 and sea ice forcing data, are available at
 [https://highresmip.org/](https://highresmip.org/). The TempestExtremes AR
 detection software is available on Zenodo at
 [https://doi.org/10.5281/zenodo.15320218](https://doi.org/10.5281/zenodo.15320218).