Are Polynyas self-sustaining?

R. F. Marsden, J. Serdula, E. Key, Peter J Minnett

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

In this paper, 441 Conductivity Temperature Depth (CTD) casts from the North Water (NOW) Polynya study were used to calculate geostrophic currents between the 10 and 200 dbar surface during April, May and June 1998. Results for April and May indicated a surface intensified southward flow of 10 to 15 cm s-1 with a small return flow along the Greenland coast in agreement with inferred currents described by Melling et al. (2001) and surface ice drifts found by Wilson et al. (2001). Southward transports at this time were 0.4-0.55 Sv in April and May. In June, however, surface currents diminished markedly: southward transports declined to 0.1-0.35 Sv, coincident with a decrease in directly measured winds over the polynya and in the surface barometric pressure difference between Grise Fjord and the Carey Islands that was used as a surrogate for the local north wind speed. There was no evident decrease in air pressure difference between Resolute and Grise Fjord, indicative of the strength of the north wind over the eastern Arctic in general. The results are consistent with present thinking that the NOW Polynya is primarily a latent heat polynya, forced by dominant north winds. The idea, broached here, is that the polynya creates its own microclimate which sustains the polynya's ice-free condition after its initial formation. The mechanism is identified by an anomalous low pressure region associated with surface buoyancy flux in the polynya and is pursued through the application of a simple geostrophic adjustment model that suggests two self-sustaining mechanisms. Firstly, the frontal intrusion of the cold ambient terrestrial air mass drives a significant surface wind that transports frazil ice to the edge of the polynya before it can congeal, Secondly, rotation at these high latitudes restricts the penetration of the front into the polynya, essentially insulating the centre from freezing temperatures.

Original languageEnglish (US)
Pages (from-to)251-265
Number of pages15
JournalAtmosphere - Ocean
Volume42
Issue number4
StatePublished - Dec 2004

Fingerprint

polynya
fjord
ice drift
ice
surface pressure
microclimate
surface wind
air mass
atmospheric pressure
buoyancy
freezing
low pressure
penetration
conductivity
wind velocity
temperature
water

ASJC Scopus subject areas

  • Atmospheric Science
  • Oceanography

Cite this

Marsden, R. F., Serdula, J., Key, E., & Minnett, P. J. (2004). Are Polynyas self-sustaining? Atmosphere - Ocean, 42(4), 251-265.

Are Polynyas self-sustaining? / Marsden, R. F.; Serdula, J.; Key, E.; Minnett, Peter J.

In: Atmosphere - Ocean, Vol. 42, No. 4, 12.2004, p. 251-265.

Research output: Contribution to journalArticle

Marsden, RF, Serdula, J, Key, E & Minnett, PJ 2004, 'Are Polynyas self-sustaining?', Atmosphere - Ocean, vol. 42, no. 4, pp. 251-265.
Marsden RF, Serdula J, Key E, Minnett PJ. Are Polynyas self-sustaining? Atmosphere - Ocean. 2004 Dec;42(4):251-265.
Marsden, R. F. ; Serdula, J. ; Key, E. ; Minnett, Peter J. / Are Polynyas self-sustaining?. In: Atmosphere - Ocean. 2004 ; Vol. 42, No. 4. pp. 251-265.
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