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Abstract:
During the melting season absorbed solar radiation is the governing energy source for surface-melt on glaciers in Iceland. Many of the desert areas near glaciers (e.g., glacio-fluvial plains, beached and sand plains, defined as dust hot spots) have unstable surfaces and are prone to dust aerosol production that can deposit in snow and glacier surfaces influencing the surface albedo and thus the radiative energy absorption.
Volcanic ash and tephra fallouts on snow- and ice-covered surfaces can enhance melt or, if the ash layer is thick enough, providing isolation, reducing melt significantly due to isolation. Surface energy balance models generally do not simulate processes affected by Light Absorbing Particle (LAP) depositions, as they are often complex to describe and can originate from sources far away from glaciated surfaces.
An energy balance model was developed with the possibility to utilize spatiotemporal albedo products developed from daily MODIS data driven by high-resolution climate forcing data to reconstruct the surface energy balance (SEB) for all Icelandic glaciers. Large impacts on the surface energy balance were observed for years with high LAPs deposits, such as volcanic eruptions in 2004, 2010, 2011 and the sand and dust rich years of 2019 and 2022.
The impacts of volcanic eruptions and other LAPs events were estimated using historical mean albedo under the same climatology forcing, to provide estimations of melt energy enhancements. The results showed that in many cases, the impacts were significant even though the glaciers were far away from the eruption site, and dust sources.
