Spatial, seasonal and interannual variability of supraglacial ponds in the Langtang Valley of Nepal, 1999–2013

• Published in: Journal of Glaciology
• Main Authors: MILES, EVAN S., WILLIS, IAN C., ARNOLD, NEIL S., STEINER, JAKOB, PELLICCIOTTI, FRANCESCA
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2016
• Subjects: Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/jog.2016.120; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143016001209

ABSTRACT Supraglacial ponds play a key role in absorbing atmospheric energy and directing it to the ice of debris-covered glaciers, but the spatial and temporal distribution of these features is not well documented. We analyse 172 Landsat TM/ETM+ scenes for the period 1999–2013 to identify thawed supraglacial ponds for the debris-covered tongues of five glaciers in the Langtang Valley of Nepal. We apply an advanced atmospheric correction routine (Landcor/6S) and use band ratio and image morphological techniques to identify ponds and validate our results with 2.5 m Cartosat-1 observations. We then characterize the spatial, seasonal and interannual patterns of ponds. We find high variability in pond incidence between glaciers (May–October means of 0.08–1.69% of debris area), with ponds most frequent in zones of low surface gradient and velocity. The ponds show pronounced seasonality, appearing in the pre-monsoon as snow melts, peaking at the monsoon onset at 2% of debris-covered area, then declining in the post-monsoon as ponds drain or freeze. Ponds are highly recurrent and persistent, with 40.5% of pond locations occurring for multiple years. Rather than a trend in pond cover over the study period, we find high interannual variability for each glacier after controlling for seasonality.