04 Apr 2023
 | 04 Apr 2023

Understanding snow saltation parameterizations: lessons from theory, experiments and numerical simulations

Daniela Brito Melo, Armin Sigmund, and Michael Lehning

Abstract. Drifting and blowing snow are important features in polar and high mountain regions. They control the surface mass balance in windy conditions and influence sublimation of snow and ice surfaces. Despite their importance, model representations in weather and climate assessments have high uncertainties because the associated physical processes are complex and highly variable in space and time. This contribution investigates the saltation system, which is the lower boundary condition for drifting and blowing snow models. Using a combination of (previous) measurements and new physics-based modeling with Large Eddy Simulations (LES), we show that the prevailing parameterizations that describe the saltation system in atmospheric models are based on contradictory assumptions: while some scaling laws are typical of a saltation system dominated by aerodynamic entrainment, others represent a saltation system controlled by splash. We show that both regimes can exist, depending on the friction velocity. Contrary to sand saltation, aerodynamic entrainment of surface particles is not negligible. It is important at low wind speeds, leading to a saltation height and near surface particle velocity which increase with the friction velocity. In a splash dominated saltation regime at higher friction velocities, the saltation height and near surface particle velocity become invariant with the friction velocity and closer to what is observed with sand. These findings are accompanied by a detailed description of the theoretical, experimental and numerical arguments behind snow saltation parameterizations. This work offers a comprehensive understanding of the snow saltation system and its scaling laws, useful for both modelers and experimentalists.

Daniela Brito Melo et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-488', Nikolas Aksamit, 07 May 2023
  • RC2: 'Comment on egusphere-2023-488', Anonymous Referee #2, 15 May 2023

Daniela Brito Melo et al.

Model code and software

CodeData_Melo_etal_2023 Daniela Brito Melo

Daniela Brito Melo et al.


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Short summary
Snow saltation – the transport of snow close to the surface – occurs when the wind blows over a snow covered surface with sufficient strength. This phenomenon is represented in several climate models, however, with a limited accuracy. By performing numerical simulations and a detailed analysis of previous works, we show that snow saltation is characterized by two different regimes. This is not properly represented in the large scale models, which hinder the quantification of snow sublimation.