Simulated Signatures of Greenland Melting in the North Atlantic: A Model Comparison With Argo Floats, Satellite Observations, and Ocean Reanalysis

Abstract

Increased Greenland ice sheet melting has an impact on global mean and regional sea level rise and the ocean circulation. In this study, we explore whether Greenland melting signatures found in ocean model simulations are visible in observations from radar altimetry, satellite gravimetry and Argo floats. We have included Greenland freshwater flux (GF) in the global Finite‐Element‐Sea ice‐Ocean Model (FESOM) for the years 1993–2016. The reference run is computed by excluding Greenland freshwater input. These experiments are performed on a low resolution (ca. 24 km) and a high resolution (ca. 6 km) eddy‐permitting mesh. For comparison with the model experiments, we use different observational data, such as Argo floats, satellite observations, and reanalyses. We find that surface GF maps into signatures in temperature and salinity down to about 100 m in the surroundings of Greenland. The simulated melting signatures are particularly visible in steric heights in Baffin Bay and Davis Strait. Here, we find an improvement of the mean square error of up to 30% when including GF. For the Nordic part of the Nordic Seas, however, we find no improvement when including GF. We compare steric heights with reanalysis data and a new setup of the inversion method from gravimetric and altimetric satellite data. We cannot confirm that the GF signatures on variables such as temperature and salinity are visible in the observations on the time scales considered. However, we find that increased model resolution often causes larger improvements than occur due to including the simulated melting effect.

Arctic freshwater impact on the Atlantic Meridional Overturning Circulation: status and prospects

“…Moreover, the sensitivity of budget analyses to choice of variable (LFC, salt), control volume (full-depth, upper ocean; whole SPNA, eastern SPNA) and data source (state estimates, circulation models) should be explored.Observe and understand SPNA freshwater dispersion. In particular, the processes controlling transport of Arctic freshwater off the Greenland and Canadian shelves into the deep SPNA occur at small space-time scales and are poorly observed, modelled and understood [62,96]. Characterize the fingerprint of Arctic anthropogenic freshening in the SPNA and recommend strategies to observe it.…”

“… Observe and understand SPNA freshwater dispersion. In particular, the processes controlling transport of Arctic freshwater off the Greenland and Canadian shelves into the deep SPNA occur at small space-time scales and are poorly observed, modelled and understood [ 62 , 96 ]. Characterize the fingerprint of Arctic anthropogenic freshening in the SPNA and recommend strategies to observe it.…”

“…One example is anthropogenic loss of the Greenland Ice Sheet (GIS), which has not yet led to detectable SPNA freshening [61,62]. Nevertheless, uncertainty exists on the fate of GIS meltwater because it depends on circulation model resolution, and how the GIS discharge is parametrized [62][63][64]. These processes are not accurately represented in the ECCOv4r4 state estimate.…”

“…One example is anthropogenic loss of the Greenland Ice Sheet (GIS), which has not yet led to detectable SPNA freshening [ 61 , 62 ]. Nevertheless, uncertainty exists on the fate of GIS meltwater because it depends on circulation model resolution, and how the GIS discharge is parametrized [ 62 – 64 ]. These processes are not accurately represented in the ECCOv4r4 state estimate.…”

High‐Resolution Simulations of the Plume Dynamics in an Idealized 79°N Glacier Cavity Using Adaptive Vertical Coordinates

“…In large‐scale ocean models without explicitly resolved glacier cavities, meltwater from fjords is often introduced at the sea surface (e.g., Stolzenberger et al., 2022). Our model results show that this is generally not realistic for fjords with an ice tongue.…”