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Fractional snow-covered area: scale-independent peak of winter parameterization
oleh: N. Helbig, Y. Bühler, L. Eberhard, C. Deschamps-Berger, C. Deschamps-Berger, S. Gascoin, M. Dumont, J. Revuelto, J. Revuelto, J. S. Deems, T. Jonas
| Format: | Article |
|---|---|
| Diterbitkan: | Copernicus Publications 2021-02-01 |
Deskripsi
<p>The spatial distribution of snow in the mountains is significantly influenced through interactions of topography with wind, precipitation, shortwave and longwave radiation, and avalanches that may relocate the accumulated snow. One of the most crucial model parameters for various applications such as weather forecasts, climate predictions and hydrological modeling is the fraction of the ground surface that is covered by snow, also called fractional snow-covered area (fSCA). While previous subgrid parameterizations for the spatial snow depth distribution and fSCA work well, performances were scale-dependent. Here, we were able to confirm a previously established empirical relationship of peak of winter parameterization for the standard deviation of snow depth <span class="inline-formula"><i>σ</i><sub>HS</sub></span> by evaluating it with 11 spatial snow depth data sets from 7 different geographic regions and snow climates with resolutions ranging from 0.1 to 3 m. An enhanced performance (mean percentage errors, MPE, decreased by 25 %) across all spatial scales <span class="inline-formula">≥</span> 200 m was achieved by recalibrating and introducing a scale-dependency in the dominant scaling variables. Scale-dependent MPEs vary between <span class="inline-formula">−</span>7 % and 3 % for <span class="inline-formula"><i>σ</i><sub>HS</sub></span> and between 0 % and 1 % for fSCA. We performed a scale- and region-dependent evaluation of the parameterizations to assess the potential performances with independent data sets. This evaluation revealed that for the majority of the regions, the MPEs mostly lie between <span class="inline-formula">±</span>10 % for <span class="inline-formula"><i>σ</i><sub>HS</sub></span> and between <span class="inline-formula">−</span>1 % and 1.5 % for fSCA. This suggests that the new parameterizations perform similarly well in most geographical regions.</p>