The University of Southampton
University of Southampton Institutional Repository

Micrometeorological processes driving snow ablation in an Alpine catchment

Micrometeorological processes driving snow ablation in an Alpine catchment
Micrometeorological processes driving snow ablation in an Alpine catchment
Mountain snow covers typically become patchy over the course of a melting season. The snow pattern during melt is mainly governed by the end of winter snow depth distribution and the local energy balance. The objective of this study is to investigate micrometeorological processes driving snow ablation in an Alpine catchment. For this purpose we combine a meteorological model (ARPS) with a fully distributed energy balance model (Alpine3D). Turbulent fluxes above melting snow are further investigated by using data from eddy-correlation systems. We compare modelled snow ablation to measured ablation rates as obtained from a series of Terrestrial Laser Scanning campaigns covering a complete ablation season. The measured ablation rates indicate that the advection of sensible heat causes locally increased ablation rates at the upwind edges of the snow patches. The effect, however, appears to be active over rather short distances except for very strong wind conditions. Neglecting this effect, the model is able to capture the mean ablation rates for early ablation periods but strongly overestimates snow ablation once the fraction of snow coverage is below a critical value. While radiation dominates snow ablation early in the season, the turbulent flux contribution becomes important late in the season. Simulation results indicate that the air temperatures appear to overestimate the local air temperature above snow patches once the snow coverage is below a critical value. Measured turbulent fluxes support these findings by suggesting a stable internal boundary layer close to the snow surface causing a strong decrease of the sensible heat flux towards the snow cover. Thus, the existence of a stable internal boundary layer above a patchy snow cover exerts a dominant control on the timing and magnitude of snow ablation for patchy snow covers.
1994-0440
2159-2196
Mott, R.
269a0451-a600-4d9f-a038-ad0de0a7d003
Egli, L.
09f83dba-7788-406c-8035-8bac97be1bc9
Grunewald, T.
827fb220-7193-40ba-a4fc-acd137479bda
Dawes, N.
32637c22-60d6-4678-a292-56922f5efa33
Manes, C.
7d9d5123-4d1b-4760-beff-d82fe0bd0acf
Bavay, M.
0c5ddcae-2680-4dc8-969b-a01ed8ef92d0
Lehning, M.
72ba397f-301c-476f-83b0-d37f7620731e
Mott, R.
269a0451-a600-4d9f-a038-ad0de0a7d003
Egli, L.
09f83dba-7788-406c-8035-8bac97be1bc9
Grunewald, T.
827fb220-7193-40ba-a4fc-acd137479bda
Dawes, N.
32637c22-60d6-4678-a292-56922f5efa33
Manes, C.
7d9d5123-4d1b-4760-beff-d82fe0bd0acf
Bavay, M.
0c5ddcae-2680-4dc8-969b-a01ed8ef92d0
Lehning, M.
72ba397f-301c-476f-83b0-d37f7620731e

Mott, R., Egli, L., Grunewald, T., Dawes, N., Manes, C., Bavay, M. and Lehning, M. (2011) Micrometeorological processes driving snow ablation in an Alpine catchment. The Cryosphere Discussions, 5, 2159-2196. (doi:10.5194/tcd-5-2159-2011).

Record type: Article

Abstract

Mountain snow covers typically become patchy over the course of a melting season. The snow pattern during melt is mainly governed by the end of winter snow depth distribution and the local energy balance. The objective of this study is to investigate micrometeorological processes driving snow ablation in an Alpine catchment. For this purpose we combine a meteorological model (ARPS) with a fully distributed energy balance model (Alpine3D). Turbulent fluxes above melting snow are further investigated by using data from eddy-correlation systems. We compare modelled snow ablation to measured ablation rates as obtained from a series of Terrestrial Laser Scanning campaigns covering a complete ablation season. The measured ablation rates indicate that the advection of sensible heat causes locally increased ablation rates at the upwind edges of the snow patches. The effect, however, appears to be active over rather short distances except for very strong wind conditions. Neglecting this effect, the model is able to capture the mean ablation rates for early ablation periods but strongly overestimates snow ablation once the fraction of snow coverage is below a critical value. While radiation dominates snow ablation early in the season, the turbulent flux contribution becomes important late in the season. Simulation results indicate that the air temperatures appear to overestimate the local air temperature above snow patches once the snow coverage is below a critical value. Measured turbulent fluxes support these findings by suggesting a stable internal boundary layer close to the snow surface causing a strong decrease of the sensible heat flux towards the snow cover. Thus, the existence of a stable internal boundary layer above a patchy snow cover exerts a dominant control on the timing and magnitude of snow ablation for patchy snow covers.

Text
Mott_et_al_2011.pdf - Other
Download (1MB)

More information

Published date: 2011
Organisations: Energy & Climate Change Group

Identifiers

Local EPrints ID: 204131
URI: http://eprints.soton.ac.uk/id/eprint/204131
ISSN: 1994-0440
PURE UUID: 35a544fe-8005-4ceb-be30-819b110503dd

Catalogue record

Date deposited: 24 Nov 2011 11:17
Last modified: 14 Mar 2024 04:30

Export record

Altmetrics

Contributors

Author: R. Mott
Author: L. Egli
Author: T. Grunewald
Author: N. Dawes
Author: C. Manes
Author: M. Bavay
Author: M. Lehning

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×