Polynya
node · earth · Both polar oceans
A persistent area of open water surrounded by sea ice - the hole rather than the ice. Two mechanisms are distinguished: a latent-heat polynya, where wind or current pushes newly formed ice away from a coast or ice shelf as fast as it forms, and a sensible-heat polynya, where warmer water rising from below keeps the surface ice-free. They matter out of all proportion to their area. Biologically they are where light reaches water in spring before the surrounding pack breaks up, and where air-breathing animals can surface in winter, so they concentrate life and the hunting that depends on it. Physically the latent-heat kind are ice factories: continuously freezing new ice rejects salt into the water beneath, and around Antarctica that dense, cold, salty water sinks off the shelf and becomes the bottom water of the world ocean.
Read in · 1
Evidence · 1
Timeline
No dated observations are stored for this object. Atlas shows what was observed and when — it does not infer a history.
Connections · 2
- Sea Icepart_of
- Antarctic Bottom Water (AABW)supplies
Assembled narrative · 1
Assembled from 30 blocks · 1 evidence · 35 related
- Story
- A persistent area of open water surrounded by sea ice - the hole rather than the ice. Two mechanisms are distinguished: a latent-heat polynya, where wind or current pushes newly formed ice away from a coast or ice shelf as fast as it forms, and a sensible-heat polynya, where warmer water rising from below keeps the surface ice-free. They matter out of all proportion to their area. Biologically they are where light reaches water in spring before the surrounding pack breaks up, and where air-breathing animals can surface in winter, so they concentrate life and the hunting that depends on it. Physically the latent-heat kind are ice factories: continuously freezing new ice rejects salt into the water beneath, and around Antarctica that dense, cold, salty water sinks off the shelf and becomes the bottom water of the world ocean.
- Knowledge
- Sea Ice
- Polynya
- Antarctic Bottom Water (AABW)
- Connections
- Sea Ice
- Antarctic Bottom Water (AABW)
- Pikialasorsuaq (the North Water Polynya)
- Polynya
- Arctic Amplification
- Antarctic Krill (Euphausia superba)
- Polar Bear (Ursus maritimus)
- Emperor Penguin (Aptenodytes forsteri)
- Halley Bay Emperor Penguin Colony
- The continuous satellite sea-ice record begins
- A long-term decline in krill density is linked to winter sea ice
- The Arctic summer minimum drops far below anything previously observed
- The lowest Arctic sea-ice extent in the satellite record
- The Halley Bay emperor colony fails and does not recover
- The emperor penguin is listed as threatened under the US Endangered Species Act
- Antarctic sea ice reaches a record low, a year after the previous one
- Polynya
- North Atlantic Deep Water (NADW)
- Weddell Sea
- Thermohaline Circulation
- Antarctic meltwater is projected to slow the abyssal cell
- Evidence
- A continuous, consistently processed record of sea-ice extent in both hemispheres exists from 1979, from which the Arctic September minima of 2007 (approximately 4.2 million km2) and 2012 (approximately 3.4 million km2) and the Antarctic February minima of 2022 and 2023 (the first below 2 million km2 in the record, and lower again the following year) are drawn. V55 VERIFICATION BASIS: nsidc.org was probed during production and refused by the network egress proxy, and the WebSearch budget was exhausted. EVERY NUMERIC VALUE IN THIS RECORD IS APPROXIMATE AND UNCHECKED, given to one or two significant figures for that reason. A curator must replace them with values read from the Sea Ice Index before publication.
Observed changes · 0
No public Signals are attached to this object. Signals show what changed and when it was observed — never a direction or a rank.
Actions
/atlas?object=PHENOMENON_POLYNYA&experience=PHENOMENON_POLYNYA