| Abstrakt: |
Submarine melting at Greenland's marine terminating glaciers is a crucial, yet poorly constrained process in the coupled ice‐ocean system. Application of Antarctic melt rate representations, derived for floating glacier tongues, to non‐floating marine terminating glaciers commonly found in Greenland, results in a dramatic underestimation of submarine melting. Here, we revisit the physical theory underlying melt rate parameterizations and leverage recently published observational data to derive a novel melt rate parameterization. This is the first parameterization that (a) consistently comprises both convective‐ and shear‐dominated melt regimes, (b) includes coefficients quantitatively constrained using observational data, and (c) is applicable to any vertical glacier front. We show that, compared to the current state‐of‐the‐art approach, the scheme provides an improved fit to observed melt rates on the scale of the terminating front, offering an opportunity to incorporate this critical missing forcing into ocean circulation models. Plain Language Summary: Where Greenland's glaciers terminate in the ocean, the relatively warm waters in the fjords melt the ice. This is a very important process, as the rate of melt determines how fast the glaciers are losing mass and inject freshwater into the ocean, which contributes to sea level rise and can change ocean currents. Unfortunately, it is still difficult to calculate how much glacial ice is melted by the warm ocean around Greenland, as it is unfeasible to measure the small melting processes so close to the calving glacier front. Up to now, melt rate calculations rely on estimates for floating glacier tongues in Antarctica, which are more accessible, but it has become increasingly apparent that important differences exist for these two cases. In this study, we try to find a better way to calculate melt rates for marine terminating glaciers with vertical fronts, by reconsidering the underlying physics of submarine melt, and by using observations of submarine melt waters near a vertical glacier front in Alaska. Key Points: Convective instabilities may govern vertical ice front melting at low ambient currents but are ignored in existing parameterizationsWe propose a novel melt parameterization for vertical fronts continuous across convective and shear regimes constrained by observationsThe contribution of background melting as opposed to melting within subglacial discharge plumes might be larger than previously thought [ABSTRACT FROM AUTHOR] |
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