Assessment and projection of the water budget over western Canada using convection-permitting weather research and forecasting simulations
<p>Water resources in cold regions in western Canada face severe risks posed by anthropogenic global warming as evapotranspiration increases and precipitation regimes shift. Although understanding the water cycle is key for addressing climate change issues, it is difficult to obtain high spati...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-07-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://hess.copernicus.org/articles/24/3677/2020/hess-24-3677-2020.pdf |
| Summary: | <p>Water resources in cold regions in western Canada face severe risks
posed by anthropogenic global warming as evapotranspiration increases
and precipitation regimes shift. Although understanding the water
cycle is key for addressing climate change issues, it is difficult to
obtain high spatial- and temporal-resolution observations of
hydroclimatic processes, especially in remote regions. Climate models
are useful tools for dissecting and diagnosing these processes,
especially the convection-permitting (CP) high-resolution regional
climate simulation, which provides advantages over lower-resolution models by explicitly representing convection. In addition to better representing
convective systems, higher spatial resolution also better represents
topography, mountain meteorology, and highly heterogeneous
geophysical features. However, there is little work with
convection-permitting regional climate models conducted over western
Canada. Focusing on the Mackenzie River and Saskatchewan River basins, this
study investigated the surface water budget and atmospheric moisture
balance in historical and representative concentration pathway (RCP8.5) projections using 4 km CP Weather
Research and Forecasting (WRF). We compared the high-resolution 4 km CP
WRF and three common reanalysis datasets, namely the North American Regional Reanalysis (NARR), the Japanese 55-year Reanalysis (JRA-55), and
European Centre for Medium-Range Weather Forecasts
reanalysis interim dataset (ERA-Interim). High-resolution WRF outperforms the reanalyses in
balancing the surface water budget in both river basins with much
lower residual terms. For the pseudo-global-warming scenario at the
end of the 21st century with representative concentration pathway (RCP8.5) radiative forcing, both the
Mackenzie River and Saskatchewan River basins show increases in the
amplitude for precipitation and evapotranspiration and a decrease in
runoff. The Saskatchewan River basin (SRB) shows a moderate increase in
precipitation in the west and a small decrease in the east. Combined
with a significant increase in evapotranspiration in a warmer climate,
the Saskatchewan River basin would have a larger deficit of water
resources than in the current climate based on the pseudo-global-warming (PGW) simulation. The
high-resolution simulation also shows that the difference of atmospheric
water vapour balance in the two river basins is due to flow
orientation and topography differences at the western boundaries of
the two basins. The sensitivity of water vapour balance to fine-scale
topography and atmospheric processes shown in this study demonstrates
that high-resolution dynamical downscaling is important for
large-scale water balance and hydrological cycles.</p> |
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| ISSN: | 1027-5606 1607-7938 |