The effect of a shift in the atmospheric energy transport scales on the Greenland ice sheet surface mass balance
- University of Tromsø - The Arctic University of Norway, Tromsø, Norway (tuomas.i.heiskanen@uit.no)
Climate change in the Arctic is likely to lead to a significant melting of ice sheets and glaciers. This will be an important driving
mechanism for future sea-level rise. During the last decades the Greenland ice sheet has lost mass at an unprecedented rate.
This has lead to the Greenland ice sheet to be an important contributor to sea-level rise. Here we test the hypothesis that a
change in the atmospheric circulation over Greenland contributes to the exceptionally negative surface mass balance observed over the
last decades.
The atmospheric transport contributes an amount of energy into the Arctic that is
comparable to that provided directly by the sun. From recently developed Fourier and wavelet based methods it has been found that
the planetary component of the latent heat transport affects that Arctic surface temperatures stronger than the decomposed dry-static
energy transport and the synoptic scale component of the latent heat transport.
The south west ablation zone of the Greenland ice-sheet is one of the main contributors to mass loss of the ice-sheet. Comparing
the ablation in this area with patterns of the divergence of latent heat transport shows that similar decadal-scale trends are found
in the surface mass balance and divergence of latent heat transport data.
During the last decades the divergence of latent heat has shifted from
synoptic scale to planetary scale, implying an increased convergence of latent heat transport by synoptic scale waves to the south
west coast of Greenland.
Through linear regressions we find that the shift from planetary scale transport convergence to synoptic scale convergence describes
approximately 25 % of the surface mass balance anomaly, since year 2000, in the south west region of Greenland. The total amount
of energy transported into this region has not changed dramatically. Hence this indicates the importance of the systems transporting
the energy or conditions under which the transport by the different wave types take place.
Transport by synoptic scale waves seems to be an important contributor to the surface mass loss of the Greenland ice
sheet. A possible explanation for this is that synoptic scale transport into the ablation zone is associated with warmer conditions
than the planetary component over the same region. Hence providing favorable conditions for ice melting, and possibly a larger
fraction of liquid precipitation. However, why this is so is still a subject we study.
Further we try to identify how different melt driving mechanisms are
associated with both planetary and synoptic scale divergence of energy transport, and which of these lead to the differing effects on
the surface mass balance of the Greenland ice sheet.
How to cite: Heiskanen, T. I. H.: The effect of a shift in the atmospheric energy transport scales on the Greenland ice sheet surface mass balance, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14215, https://doi.org/10.5194/egusphere-egu21-14215, 2021.
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