The effect of a shift in the atmospheric energy transport scales on the Greenland ice sheet surface mass balance
Authors: Heiskanen Tuomas Ilkka Henrikki 
Published: March 2021

&lt;p&gt;&amp;#160;Climate change in the Arctic is likely to lead to a significant melting of ice sheets and glaciers. This will be an important driving&lt;br&gt;&amp;#160; mechanism for future sea-level rise. During the last decades the Greenland ice sheet has lost mass at an unprecedented rate.&amp;#160;&lt;br&gt;&amp;#160; This has lead to the Greenland ice sheet to be an important contributor to sea-level rise. Here we test the hypothesis that a&amp;#160;&lt;br&gt;&amp;#160; change in the atmospheric circulation over Greenland contributes to the exceptionally negative surface mass balance observed over the&lt;br&gt;&amp;#160; last decades.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160; The atmospheric transport contributes an amount of energy into the Arctic that is&amp;#160;&lt;br&gt;&amp;#160; comparable to that provided directly by the sun. From recently developed Fourier and wavelet based methods it has been found that&amp;#160;&lt;br&gt;&amp;#160; the planetary component of the latent heat transport affects that Arctic surface temperatures stronger than the decomposed dry-static&amp;#160;&lt;br&gt;&amp;#160; energy transport and the synoptic scale component of the latent heat transport.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160; The south west ablation zone of the Greenland ice-sheet is one of the main contributors to mass loss of the ice-sheet. Comparing&amp;#160;&lt;br&gt;&amp;#160; the ablation in this area with patterns of the divergence of latent heat transport shows that similar decadal-scale trends are found&amp;#160;&lt;br&gt;&amp;#160; in the surface mass balance and divergence of latent heat transport data.&amp;#160;&lt;br&gt;&amp;#160; During the last decades the divergence of latent heat has shifted from&amp;#160;&lt;br&gt;&amp;#160; synoptic scale to planetary scale, implying an increased convergence of latent heat transport by synoptic scale waves to the south&lt;br&gt;&amp;#160; west coast of Greenland.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160; Through linear regressions we find that the shift from planetary scale transport convergence to synoptic scale convergence describes&lt;br&gt;&amp;#160; approximately 25 % of the surface mass balance anomaly, since year 2000, in the south west region of Greenland. The total amount&amp;#160;&lt;br&gt;&amp;#160; of energy transported into this region has not changed dramatically. Hence this indicates the importance of the systems transporting&amp;#160;&lt;br&gt;&amp;#160; the energy or conditions under which the transport by the different wave types take place.&amp;#160;&lt;br&gt;&amp;#160; Transport by synoptic scale waves seems to be an important contributor to the surface mass loss of the Greenland ice&lt;br&gt;&amp;#160; sheet. A possible explanation for this is that synoptic scale transport into the ablation zone is associated with warmer conditions&lt;br&gt;&amp;#160; than the planetary component over the same region. Hence providing favorable conditions for ice melting, and possibly a larger&amp;#160;&lt;br&gt;&amp;#160; fraction of liquid precipitation. However, why this is so is still a subject we study.&amp;#160;&lt;br&gt;&amp;#160; Further we try to identify how different melt driving mechanisms are&amp;#160;&lt;br&gt;&amp;#160; associated with both planetary and synoptic scale divergence of energy transport, and which of these lead to the differing effects on&lt;br&gt;&amp;#160; the surface mass balance of the Greenland ice sheet.&lt;/p&gt;