Not an update of current conditions in the Beaufort Sea, but some science for your reading pleasure.
This is a guest blog by Alek Petty, a postdoc at NASA’s Goddard Space Flight Center and the University of Maryland, specializing in Arctic and Antarctic sea ice variability. Alek has just published a paper in the Journal of Geophysical Research called Sea ice circulation around the Beaufort Gyre: The changing role of wind forcing and the sea ice state, and below he explains in detail what the paper is about (also be sure to check out his website).
Sea ice circulation around the Beaufort Gyre
The Beaufort Sea ice pack has experienced a significant breakup event in recent weeks. This has coincided with some classic Beaufort Gyre ice drift circulations. In this blog, I want to talk a bit more about the sea ice circulation around the Beaufort Gyre, why it’s important, and why it might have changed over the last few decades.
The Arctic is replenished with around ten thousand gigatons of fresh water every year from river run-off into the Arctic basin, Pacific Water inflow (through the Bering Strait), precipitation and – increasingly – sea ice melt.
Figure 1: Mean dynamic topography (MDT) of the Arctic Ocean [from Farrell et al., 2012, GRL]. Grey lines are bathymetry contours [Jakobsson et al., 2012] and the black boxes indicate the Beaufort Gyre study region.
The predominantly clockwise winds over the northern Beaufort Sea draw in a significant fraction of this freshwater – through a process called Ekman pumping – resulting in a characteristic doming of the ocean surface (a ‘spin-up’ of the ocean as it is often called).
The combined forces of gravity and Coriolis drive a clockwise ocean current that circulates this relatively fresh surface water – along with its overlying sea ice cover – around the center of the dome (also clockwise). The end result is one of the most prominent features of the Arctic Ocean: the Beaufort Gyre (see Figure 1).
The sea ice sandwiched between the atmosphere and ocean responds to the combined effects of wind and ocean drag and thus modulates how effectively the winds can ‘spin up’ the ocean. The interaction between winds, ocean currents and sea ice are intrinsically linked, making it an extremely challenging system to study. We’ll get back to this point later.