Multifractal Analysis of Snowfall Recorded Using a 2D Video Disdrometer

Timothy H. Raupach (1) , Auguste Gires (2) , Ioulia Tchiguirinskaia (2) , D Schertzer (2) , Alexis Berne (1)

1 EPFL - Ecole Polytechnique Fédérale de Lausanne
2 HM&Co - Hydrologie, Météorologie et Complexité

Universal multifractal (UM) analysis was used to investigate the scaling properties of snowfall at high temporal and spatial resolutions. Snowfall data were recorded using a 2D video disdrometer (2DVD) in the Swiss Alps. Six 1-h-long periods of snowfall, half in calm and half in light wind conditions, were selected for analysis. UM analysis was performed on reconstructed 35-m vertical columns of snowfall structure, snowfall time series at 100-ms resolution, and two-dimensional snowflake accumulation maps over a 5.12 5.12 cm2 area. Multifractal scaling was observed for the vertical structure of snow particle number concentration, for scales between about 35 and 4.4 m, and sometimes down to about 0.5 m. At smaller scales, no scaling was observed. In high-resolution time series of snowfall, evidence of scaling was found for scales between about 7 min and ~26 s in most of the analyzed hours. Snowflake accumulations within a subset of the small sampling area of the 2DVD showed no scaling properties, suggesting homogeneous structure in snowfall at the very small (~5 cm) scale, which agrees with the results for vertical structure and time series.

Mots clés: Snow; multifractals; Small scale processes; Snowfall; Microscale processes/variability

Domaines: Météorologie; Sciences de l'environnement

Timothy H. Raupach, Auguste Gires, Ioulia Tchiguirinskaia, D Schertzer, Alexis Berne. Multifractal Analysis of Snowfall Recorded Using a 2D Video Disdrometer. Journal of Hydrometeorology, 2017, 18 (9), pp.2453-2468. ⟨10.1175/JHM-D-16-0224.1⟩. ⟨hal-01673434⟩