Research

HIGH MOUNTAIN ASIA GLACIER MASS BALANCES

Altimetric studies revealed heterogenous pattern of surface elevation changes of High Mountain Asia (HMA) glaciers (e.g. Kääb et al., 2015). Unfortunately, these studies rely on ICESat altimeter satellite, which operated only between 2003 and 2009 and which has a scarse spatial sampling.

Glacier elevation changes (2003-2008) measured by ICESat altimeter. Figure from Kääb et al. (2015).

References:
– Kääb A. et al. (2015),  Brief Communication: Contending estimates of 2003–2008
glacier mass balance over the Pamir–Karakoram–Himalaya, The cryosphere.

 

ICE CLIFFS ON DEBRIS-COVERED GLACIERS OF THE NEPALESE HIMALAYAS

Ice cliffs on debris-covered glaciers might play an important role in the energy balance of the glacier and contribute significantly to the total amount of melt (Steiner et al., 2015; Buri et al., 2016). We try to assess their total contribution to the glacier mass balance by using various remote sensing and field based photogrammetric 3-D models.

References:
– Brun F. et al. (2016), Quantifying volume loss from ice cliffs on debris-covered glaciers using high-resolution terrestrial and aerial photogrammetry, Journal of Glaciology.
– Buri P. et al. (2016), A grid-based model of backwasting of supraglacial ice cliffs on debris-covered glaciers, Annals of Glaciology.
– Steiner J. et al. (2015), Modelling ice-cliff backwasting on a debris-covered glacier in the
Nepalese Himalaya, Journal of Glaciology.

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Ice cliff and supraglacial lake on Changri Nup Glacier, Everest region, Nepal

ALBEDO MEASUREMENTS AND LINKS WITH GLACIER MASS BALANCE

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Automatic weather station of Mera summit (Photo: Patrick Wagnon)

Albedo of glacier surfaces is a strong driver of the mass balance as it controls the amount of energy transferred to the glacier. Dumont et al. (2012) showed that the albedo measured from space (by MODIS sensor) could be used as a proxy for mass balance for Saint-Sorlin Glacier (French Alps).

We adapted this method to the Himalayas and showed that it worked well for Chhota Shigri Glacier (in the western part of the range), but didn’t work for Mera Glacier located in the central Himalayas. We attributed these differences to the different climate influences dominating for each glacier.

References:
– Brun, F., M. Dumont, P. Wagnon, E. Berthier, M. F. Azam, J. M. Shea, P. Sirguey, A. Rabatel, and Al. Ramanathan (2015), Seasonal changes in surface albedo of Himalayan glaciers from MODIS data and links with the annual mass balance, The Cryosphere, 9 (1), 341–355, 10.5194/ tc-9-341-2015.
– Dumont, M., Gardelle, J., Sirguey, P., Guillot, A., Six, D., Rabatel, A., and Arnaud, Y.: Linking glacier annual mass balance and glacier albedo retrieved from MODIS data, The Cryosphere, 6, 1527–1539, doi:10.5194/tc-6-1527-2012, 2012.

 

EXPERIMENTAL GEOMORPHOLOGY – EROSION BY SUSPENDED SEDIMENTS

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Figure showing the good match between the model and the experimental data for small grain sizes (Scheingross et al., 2014)

Erosion by suspended sediment is often assumed to be negligible compared with the bedload erosion in bedrock incision models. Nevertheless, some recent model developments (Lamb et al., 2008) suggested that suspended sediment could account for up to half of the total erosion.

We measured the erosion by suspended sediment in abrasion mills (similar to the one used by Sklar and Dietrich (2001)) and demonstrated their non negligible contribution to total erosion.

References:
– Scheingross, J. S., F. Brun, D. Y. Lo, K. Omerdin, and M. P. Lamb (2014), Experimental evidence for fluvial bedrock incision by suspended and bedload sediment, Geology, 42, 523–526, 10.1130/G35432.1. (pdf)
– Lamb, M. P., W. E. Dietrich, and L. S. Sklar (2008), A model for fluvial bedrock incision by impacting suspended and bed load sediment, Journal of Geophysical Research, 113 (F3), F03,025.
– Sklar, L. S., and W. E. Dietrich (2001), Sediment and rock strength controls on river incision into bedrock, Geology, 29 (12), 10871090.