Title
Orographic effects on snow deposition patterns in mountainous terrain
Date Issued
16 February 2014
Access level
open access
Resource Type
journal article
Author(s)
Publisher(s)
Wiley-Blackwell
Abstract
Orographic lifting of air masses and other topographically modified flows induce cloud and precipitation formation at larger scales and preferential deposition of precipitation at smaller scales. In this study, we examine orographic effects on small-scale snowfall patterns in Alpine terrain. A polarimetric X-band radar was deployed in the area of Davos (Switzerland) to determine the spatial variability of precipitation. In order to relate measured precipitation fields to flow dynamics, we model flow fields with the atmospheric prediction model “Advanced Regional Prediction System.” Additionally, we compare radar reflectivity fields with snow accumulation at the surface as modeled by Alpine3D. We investigate the small-scale precipitation dynamics for one heavy snowfall event in March 2011 at a high resolution of 75 m. The analysis of the vertical and horizontal distribution of radar reflectivity at horizontal polarization and differential reflectivity shows polarimetric signatures of orographic snowfall enhancement near the summit region. Increasing radar reflectivity at horizontal polarization over the windward slopes toward the crest and downwind decreasing reflectivity over the leeward slopes is observed. The temporal variation of the location of maximum concentration of snow particles is partly attributed to the effect of preferential deposition of snowfall: For situations with strong horizontal winds, the concentration maximum is shifted from the ridge crest toward the leeward slopes. Qualitatively, we discuss the relative role of cloud microphysics such as the seeder-feeder mechanism versus atmospheric particle transport in generating the observed snow deposition at the ground.
Start page
1419
End page
1439
Volume
119
Issue
3
Language
English
OCDE Knowledge area
Geografía física
Geografía física
Geoquímica, Geofísica
Ciencia del suelo
Geociencias, Multidisciplinar
Scopus EID
2-s2.0-84898951641
Source
Journal of Geophysical Research
ISSN of the container
01480227
Sponsor(s)
The work was funded by the Competence Center for Environment and Sustainability CCES (SwissEx Science and SwissEx) and by the Swiss National Science Foundation (grant 200021-125064 and grant 2000,21-125332). We thank Thomas Grünewald, Charles Fierz, and Matthew von Pokorny for their thoughtful comments, valuable discussions, and language editing. We thank Jakobshornbahn and in particular Vali Meier for their support during the radar measurement campaign. We also thank Jessica Lundquist and the anonymous reviewers who helped to improve the paper.
Sources of information:
Directorio de Producción Científica
Scopus