Abstract. Recent modelling studies have indicated that icebergs alter the ocean's state, the thickness of sea ice and the prevailing atmospheric conditions, in short play an active role in the climate system. The icebergs' impact is due to their slowly released melt water which freshens and cools the ocean. The spatial distribution of the icebergs and thus their melt water depends on the forces (atmospheric and oceanic) acting on them as well as on the icebergs' size. The studies conducted so far have in common that the icebergs were moved by reconstructed or modelled forcing fields and that the initial size distribution of the icebergs was prescribed according to present day observations. To address these shortcomings, we used the climate model iLOVECLIM that includes actively coupled ice-sheet and iceberg modules, to conduct 15 sensitivity experiments to analyse (1) the impact of the forcing fields (atmospheric vs. oceanic) on the icebergs' distribution and melt flux, and (2) the effect of the used initial iceberg size on the resulting Northern Hemisphere climate and ice sheet under different climate conditions (pre-industrial, strong/weak radiative forcing). Our results show that, under equilibrated pre-industrial conditions, the oceanic currents cause the bergs to stay close to the Greenland and North American coast, whereas the atmospheric forcing quickly distributes them further away from their calving site. These different characteristics strongly affect the lifetime of icebergs, since the wind-driven icebergs melt up to two years faster as they are quickly distributed into the relatively warm North Atlantic waters. Moreover, we find that local variations in the spatial distribution due to different iceberg sizes do not result in different climate states and Greenland ice sheet volume, independent of the prevailing climate conditions (pre-industrial, warming or cooling climate). Therefore, we conclude that local differences in the distribution of their melt flux do not alter the prevailing Northern Hemisphere climate and ice sheet under equilibrated conditions und constant supply of icebergs. Furthermore, our results suggest that the applied radiative forcing scenarios have a stronger impact on climate than the used initial size distribution of the icebergs.
Time-Lapse Imaging of Ag3Sn Thermal Coarsening in Sn-3Ag-0.5Cu Solder Joints
