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Understanding Arctic Polynyas and Their Impact on Oceanic Conveyor Belt Changes

This document explores the phenomenon of polynyas—persistent openings in sea ice that form year after year in the Arctic. It distinguishes between two types of polynyas: sensible and katabatic. These openings play a crucial role in the Arctic's oceanic conveyor belt, facilitating the inflow of warmer Atlantic waters and outflow to surrounding oceans. The analysis covers the recent decline in Arctic sea ice extent, the implications of accelerated ice loss due to rising temperatures, and its effects on local ecology, weather patterns, and ocean circulation.

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Understanding Arctic Polynyas and Their Impact on Oceanic Conveyor Belt Changes

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Presentation Transcript

  1. GEOS 110 FALL 2011 SEA ICE

  2. Polynyas – openings in the ice • Persistent, forming year after year • 2 types: Sensible & Katabatic

  3. Polynyas – openings in the iceKatabatic – Dense Drainage Winds

  4. Understanding and Projecting the Changes in the Oceanic Conveyor Belt is a Critical Question for Science

  5. Arctic inflow Arctic outflow The North Atlantic Current provides about 60% of the inflow to the Arctic Ocean bringing warmer water from the Atlantic Ocean. Some water also moves into the Arctic Ocean from the Bering Sea and the Pacific Ocean, by way of the Bering Strait. Water flows from the Arctic Ocean into the Pacific and Atlantic Oceans, as well as into a number of surrounding seas. By far, the greatest volume of water leaves the Arctic Ocean through the passage between Greenland and Spitsbergen.

  6. Minimum arctic sea-ice extent from 1979 to 2007

  7. observations vs. models IPCC FAR model ensemble mean of all models observed sea ice decline is 50 years ahead of expectation from models forced by GHG’s (and other human and natural radiative forcings discussed earlier) suggesting models do not capture all relevant interactions

  8. “A linear increase in heat in the Arctic will lead to a non-linear, and accelerating, loss of ice”

  9. impacts of an summer-ice free Arctic ? • sharply warmer Arctic Autumn and Winter from increased O-A heat fluxes (polar amplification of warming) • local ecological and human impacts • altered weather patterns outside the Arctic (due to altered patterns of heating and pressure) • altered salinity and ocean circulation no evidence of summer-ice free Arctic in last million years

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