Intra-Annual Snow Cover Variability on the Quelccaya Ice Cap (Peru)
Abstract
The remarkable retreat of tropical glaciers in the Peruvian Andes poses additional water supply challenges to downstream communities with growing populations. For many communities, a substantial portion of water demands is met via runoff from nearby melting glaciers, particularly during the dry season and drought years. The location and rate of melting on tropical glaciers are dictated, in part, by the position of snow cover and how it changes with time. Previous research on Andean tropical glaciers has analyzed inter-annual snow cover variability, but additional research is needed on shorter timescales.
We track intra-annual snow cover variability on the Quelccaya Ice Cap in Peru by analyzing all Landsat images from 2000 and 2001 where the ice cap is cloud-free. To identify snow cover on the ice cap, we apply thresholds on green and near-infrared bands. For elevation data, we use the 2000 Shuttle Radar Topography Mission (STRM) digital elevation model (DEM). Most cloud-free scenes are from the dry season (June - August), but scenes span from March to October. For both years, the amount of snow cover decreased from March to August, and the minimum snow cover and maximum snow line elevation occurred at the start of August. Snow cover fluctuated slightly during the dry season due to rare snowfall events, but complete coverage did not occur until early September in 2000. In 2001, complete coverage did not occur within the window of our analysis. Dry season snow cover trends on the Quelccaya Ice Cap are similar to snow cover trends on mid-latitude glaciers during the summer, which suggests that liquid precipitation may fall on the periphery of the ice cap. Additionally, we derive an empirical relationship between the snow cover area and snow line elevation that can be used to predict future snow cover changes. This research delivers new insights about intra-annual snow cover variability on the Quelccaya Ice Cap and provides data that can be used in future mass balance studies.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C31B1505N
- Keywords:
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- 0720 Glaciers;
- CRYOSPHERE;
- 0758 Remote sensing;
- CRYOSPHERE;
- 0762 Mass balance;
- CRYOSPHERE;
- 0776 Glaciology;
- CRYOSPHERE