Abstract
AbstractGlaciers located in western High Mountain Asia (HMA) have shown mass gain or limited mass losses compared to other mountain regions since ~2000. Increases in accumulation may be responsible. Although no contemporary measurements exist to explore this hypothesis, extensive historic measurements including firn density, stratigraphy and accumulation rates at ~4400 m a.s.l. on Abramov Glacier, Pamir Alay, provide valuable indications of accumulation changes. Abramov Glacier is located at the northern margin of western HMA. In this study, we assess unique historical firn data of Abramov Glacier from the 1970s to evaluate past firn conditions in this data sparse region. The current firn state is investigated based on a series of in situ measurements including firn cores and ground-penetrating radar measurements performed in 2018. We compare the legacy data with contemporary firn characteristics. Our results indicate a high year-to-year variability, but generally increasing net accumulation during the last 60 years on Abramov Glacier, with 0.84 ± 0.22 m w.e. for 2011–18 compared to 0.68 ± 0.32 m w.e. for 1965–72 and 0.59 ± 0.22 m w.e. for 1970–97. These results from in situ data provide ground truth for the data-sparse western HMA.
Highlights
The firn cover of mountain glaciers is expected to undergo changes related to global warming
We find an increase of net accumulation rates
Our results suggest that the accumulation area of Abramov Glacier is affected by this precipitation increase
Summary
The firn cover of mountain glaciers is expected to undergo changes related to global warming. Net accumulation rates derived from firn cores provide information on climatic conditions in the accumulation area of glaciers (Schwikowski and others, 2013) and represent amount of solid precipitation (Sold and others, 2015). Melt conditions at the glacier surface produce meltwater, which percolates through the firn column and may build ice lenses when refreezing within the firn column (Benson, 1996). Changes in firn stratigraphy may reflect varying atmospheric conditions. Firn temperatures reflect the short- and mid-term evolution of the energy balance at the glacier surface (Hoelzle and others, 2011). The repeated assessment of firn characteristics provides information about climate change, which is especially valuable for data sparse regions such as High Mountain Asia (HMA). Mayer and others (2014) showed that in situ measurements from snow pits on a remotely located high elevation site can be related to more general meteorological information
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