the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
The importance of model horizontal resolution for improved estimation of Snow Water Equivalent in a mountainous region of Western Canada
Abstract. Accurate estimation of snow water equivalent (SWE) over high mountainous regions is essential to support water resource management. Due to the sparse distribution of in situ observations, models have been used to estimate SWE. However, the influence of horizontal resolution on the accuracy of simulations remains poorly understood. This study evaluates the potential of the Weather Research and Forecasting (WRF) model at horizontal resolutions of 9, 3 and 1 km to estimate the daily values of SWE over the mountainous South Saskatchewan River Basin (SSRB) in Western Canada, for a representative water year, 2017–18. Results show an accumulation period from October 2017 to the annual peak in April 2018, followed by a melting period to the end of water year. All WRF simulations tend to underestimate annual SWE, with largest biases (up to 58 kg/m2, i.e. relatively 24 %) at higher elevations and coarser horizontal resolution. The two higher-resolution simulations capture the magnitude (and timing) of peak SWE very accurately, with only a 3 to 6 % low bias for 1 km and 3 km simulations, respectively. This demonstrates that a 3 km resolution may be appropriate for estimating SWE accumulation across the region. A relationship is identified between model elevation bias and SWE biases, suggesting that the smoothing of topographic features at lower horizontal resolution leads to lower grid cell elevations, warmer temperatures, and lower SWE. Overall, high resolution WRF simulations can provide reliable SWE values as an accurate input for hydrologic modeling over a sparsely monitored mountainous catchment.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2024-42', Anonymous Referee #1, 19 Mar 2024
The comment was uploaded in the form of a supplement
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AC1: 'Reply on RC1', Samaneh Sabetghadam, 10 Jun 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-42/egusphere-2024-42-AC1-supplement.pdf
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AC1: 'Reply on RC1', Samaneh Sabetghadam, 10 Jun 2024
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RC2: 'Comment on egusphere-2024-42', Anonymous Referee #2, 14 May 2024
In general it is hard to read the figures — the authors should consider saving them at a higher resolution and/or increasing font sizes. This is making it harder to interpret the figures.
"Figure 2. Temporal variation of SWE, from CanSWE data and WRF model resolution over the SSRB region. The SWEdata are aggregated for all stations inside the innermost domain. The spikes in the graph correspond to snowfall events."
Do the spikes imply that the snow accumulated and then melts, or that this is a data artifact? The authors should state what they think is actually causing the spikes. It seems unusual to have the spikes consistent across all of the CanSWE observations.
"Figure 6. Simulated mean SWE (kg/m2)"
kg/m2 should be properly formatted
"is is because the actual topography and associated elevation will typically be much more variable over an area of 81 km2 than over 1 km..."
Same here — correctly format km2.
"The large bias in the coarsest resolution also may be due to the incapability of the WRF-9km to simulate the processes that are responsible for snow deposition and erosion in mountainous areas (Mott et al., 2018; Raparelli et al. 2021)."
It is not clear what "snow erosion" is in this context. Maybe "snow redistribution"? The latter is the more commonly used term.
Citation: https://doi.org/10.5194/egusphere-2024-42-RC2 -
AC2: 'Reply on RC2', Samaneh Sabetghadam, 10 Jun 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-42/egusphere-2024-42-AC2-supplement.pdf
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AC2: 'Reply on RC2', Samaneh Sabetghadam, 10 Jun 2024
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