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The Impact of Summer Ice Dynamics on the Surface Heat Budget of the Arctic Ocean |
CRREL, CRREL, Oregon State University
jrichtermenge@crrel.usace.army.mil
It is understood that winter ice dynamics play an important role in the energy budget of the air-ice-ocean system, through the formation of leads and ridges. In summer, thermodynamic processes cause a transition in the ice pack from a mechanical continuum to an ensemble of floes that move in a state of free drift, with little floe-floe interaction. Results from the recent SHEBA experiment have demonstrated that even under summer conditions, ice dynamics can still cause dramatic changes in the characteristics of the ice-ocean matrix that affect the energy budget. To illustrate this, we present observations taken before and after a period of sustained, moderate winds in late July, which was preceded by an extended period of low winds. These conditions resulted in significant differential motion of ice floes in the vicinity of SHEBA. The measurements include the mass balance of the ice cover; the distribution of ice and open water; and salinity and temperature profiles in leads. The data show that after the storm there was a significant change in the amount and distribution of open water areas; that there was an increase in the rate of bottom ablation; and that a stratified layer of warm, freshwater that had formed at the top of leads during melt had become mixed.
