Investigating Glacier Surface Conditions using High-Definition Ground Based Infrared Imagery: Insight from the Cordillera Blanca, Peru

Abstract:

The Cordillera Blanca, Peru, has the highest concentration of glaciers in the tropics. These glaciers, which in some valleys provide up to 70% of the dry season runoff, are rapidly retreating, with potential impacts on water resources. To predict the future changes in water resource in the region, it is important to better understand the processes driving tropical glacier ablation at the headwater of these systems. However, due to the glaciers’ high altitude and the remote location, new techniques are needed to investigate these processes. Here we use high-definition ground-based infrared thermal imagery, paired with traditional weather monitoring instruments located on and adjacent to the glacier, to obtain high temporal and spatial resolution temperature maps of the surface of the Cuchillacocha glacier in the Cordillera Blanca. For four consecutive dry seasons (July 2011-2014), 24 to 48 hours of time-lapse imagery (5-30 minute spacing) of the glacier surface and surrounding area were acquired in conjunction with climate data. We compare the spatial and temporal variability of the surface temperature with numerous factors, including the surface conditions (e.g. ice, firn, debris cover, etc.), the thermal gradient at the edge of the glacier and with night time radiative cooling under different atmospheric conditions. The results show that sub-daily fluctuations in runoff from the glacier can be explained in large part by the incoming solar radiation and that the heating not only of the ice surface, but the surround bedrock, are important controls on the rate of meltwater generation. This study shows the potential utility for collecting and analyzing ground based infrared imagery for glacier studies, with implications for hydrologic and water resource applications.