• UGI USER
  • May 07, 2024
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POLYNYAS:

Why in the news?

Polynyas release more heat and moisture, fueling cloud formation, trapping heat, and hindering sea ice refreezing.

 

source:oceanbites

About Polynyas:

  • A polynya is an area of open water surrounded by sea ice, categorised into coastal and mid-sea types.
  • Coastal polynyas form near Antarctic and Arctic coasts due to strong winds pushing ice away, while mid-sea polynyas occur sporadically within ice packs, often triggered by specific atmospheric conditions.
  • Coastal polynyas form through sensible and latent heat processes, influenced by warm water upwelling or katabatic winds driving ice away from fixed boundaries.
  • Mid-sea polynyas result from atmospheric conditions like polar cyclones or cold fronts, causing ice drift in opposite directions and opening ice packs.
  • Polynyas serve as critical habitats for marine life, fostering biodiversity and supporting the food chain.
What is Antarctic Bottom Water (AABW)?

  • Antarctic Bottom Water (AABW) is dense, highly saline water in the Southern Ocean’s abyssal layer, crucial for global ocean circulation.
  • Coastal polynyas contribute to AABW formation by increasing seawater salinity through brine rejection during sea ice formation.
  • Antarctic polynyas result from diverging ice masses, forming exposed sea water that freezes over, contributing to AABW creation.

About Polynya blooms:

  • Polynya blooms occur in open water amidst ice-covered regions, fostering rapid phytoplankton growth due to increased sunlight penetration and nutrient-rich upwelling.
  • Lack of sea ice allows deeper light penetration, promoting elevated phytoplankton growth compared to ice-covered waters.
  • Upwelling transports nutrient-rich water to the surface, further enhancing polynya bloom conditions.

Understanding the Maud Rise polynya:

  • The Maud Rise polynya, named after a submerged mountain, appears in early spring and sometimes winter.
  • Ocean currents driven by the Weddell Gyre bring warm water to the surface, melting sea ice.