Qualche aggiornamento
dal sito NSDIC:
The thickness of sea ice at the beginning of spring plays a role in how much ice survives summer melt, so we pay attention to factors that influence ice thickness, such as ice motion. Ice motion is determined by winds and other factors, which in turn are influenced by weather patterns such as the Arctic Oscillation.
In February, the strongly negative phase of the Arctic Oscillation was associated with a strong Beaufort Gyre, enhancing ice motion from the western to the eastern Arctic. A weaker Transpolar Drift Stream also slowed the movement of ice from the Siberian coast of Russia across the Arctic basin, and reduced ice flow out of Fram Strait.
The wind pattern changed in March, when the Arctic Oscillation went into a more neutral phase. As a result, the flow of ice sped up through Fram Strait and along the coast of Greenland. This pattern helps to remove older ice from the central Arctic, pushing it toward the warm waters of the North Atlantic, where it will melt.
In past decades, a strong Beaufort Gyre tended to retain old, thick ice in the Arctic Ocean. However, this may no longer hold true, because in recent years ice transiting the Beaufort Gyre tends not to survive the summer melt season. This summer’s weather conditions may be key to the survival of this older ice.
|