Global 21st Century Wind-Wave Climate Projections Using Australasian CORDEX Downscaled CMIP6 Wind Forcing (with spectral partitions)

Full description

This dataset contains archived 3-hourly outputs from global wave climate simulations regridded at 0.5-degree resolution using the WaveWatch III model (v6.07), forced by higher-resolution CORDEX-downscaled CMIP6 wind fields. It is intended to support regional to global wind-wave climate assessments, particularly over the Australasian domain, and enables comparison with projections based on coarser-resolution CMIP6 GCM wind forcing.

The simulations use an Irregular-Regular-Irregular (IRI) three-grid system, which enables accurate representation of wave processes in the polar regions while maintaining global coverage. WaveWatch III was run using the ST6 source term physics. The wave model configuration, including grid system, physics settings, and spectral resolution, is consistent with the previously published "CMIP6 global wind-wave 21st century climate projections – combined dataset" (http://hdl.handle.net/102.100.100/601698?index=1). However, NOTE THAT both the wind input and the output variables in this dataset differ, as detailed below and in the Lineage section.
Outputs are provided for 30-year time slices for historical and future climate scenarios, covering the following periods:

- Historical (1985–2014)
- End of 21st century (2071–2100) under three Shared Socioeconomic Pathways (SSPs):
SSP1-2.6 (low emissions)
SSP3-7.0 (medium–high emissions)
SSP5-8.5 (high emissions)

An important update over the previous wave climate simulations is the inclusion of a comprehensive set of integral parameter partitions (see list below), which are provided globally and allow for spectral reconstruction of sea states anywhere around the globe. The data are available at each model output time step and include spatial coordinates (longitude, latitude) and time, along with the following variables:

uwnd, vwnd – Eastward and northward components of 10 m wind
hs – Significant wave height
t01, t02, t0m1 – Mean wave periods (based on different spectral moments)
fp – Peak wave frequency
dir – Mean wave direction
spr – Directional spread of the wave field
dp – Peak wave direction
CgE – Wave energy flux

Partitioned wave parameters are provided for up to four distinct wave systems per time step:

phs0–4 – Significant wave height for each partition
ptp0–4 – Peak period for each partition
pdir0–4 – Mean wave direction for each partition
pspr0–4 – Directional spread for each partition
pdp0–4 – Peak wave direction for each partition
pqp0–4 – Wave peakedness parameter for each partition
ppe0–4 – Peak enhancement factor (gamma) for each partition

The dataset also includes directional wave spectra, which were extracted to support dynamical downscaling using the CCHaPS SCHISM WWMIII wave and hydrodynamic modelling framework. Spectra are provided for two domains (see Supp. Material document):

ww3_ounp_SCHISM – covering the model boundary points used in the SCHISM-WWMIII system
ww3_ounp_VCboun – covering a broader region around southeast Australia, to support future wave climate downscaling in the area
Lineage: The WaveWatch III simulations were forced by 3-hourly CMIP6 CMIP GCM surface wind fields downscaled with two CORDEX-Australasia Regional Climate Models (RCMs): the Conformal Cubic Atmospheric Model (CCAM) and the Bureau of Meteorology Atmospheric Regional Projections for Australia (BARPA-R). The GCMs downscaled are the ACCESS-CM2 model (realisation r4i1p1f1) and the EC-Earth3 model (realisation r1i1p1f1).

- CCAM (Conformal Cubic Atmospheric Model) is a variable-resolution global atmospheric model based on a C384 stretched grid (Schmidt factor = 2.1), providing high spatial resolution over the Australasian region. The grid resolution ranges from approximately 12.5 km in the Australasian focus region to ~150 km elsewhere.

- BARPA-R (Bureau Atmospheric Regional Projections for Australia) is a land–atmosphere limited-area Regional Climate Model (RCM) developed by the Australian Bureau of Meteorology. It operates at a horizontal resolution of 17 km and is used to provide dynamically downscaled regional wind forcing over Australia. Being this is a limited-area RCM, the regional BARPA-R high-resolution wind speed field is blended in the background CMIP6 GCM wind input. To ensure a smooth transition between the high-resolution BARPA-R wind fields and the coarser GCM data, a blending procedure was applied within a 10-degree buffer zone along the interior edge of the BARPA-R domain boundary. This blending uses a half-Gaussian weighting function. The result is a seamless spatial merge that avoids artificial discontinuities or sharp gradients in the wind field at the edge of the BARPA-R domain.

Linearly interpolated daily sea ice concentrations were taken from the corresponding ACCESS-CM2 and EC-Earth3 CMIP coarse-resolution GCMs.