Author(s): Stephen Ackley; Madison M. Smith; Peter Guest; Agnieszka Herman; Hayley Shen
Linked Author(s):
Keywords: Sea Ice; Ice Formation; Growth and Dynamics
Abstract: Antarctic coastal polynyas have been coined as “ice factories” because of the high ice formation rates under the influence of cold katabatic winds from the Antarctic continent. Ice forms at high rates in the open water areas created by the wind-blown advection of the new ice formed. During the May 2017 PIPERS cruise into Terra Nova Bay (TNB) in the Ross Sea, we observed unique coupling between the winds, waves and ice formation rates in TNB. Spectral wave measurements from SWIFT buoys revealed significant wave heights exceeding 2m. Observation of the newly formed ice showed the primary ice type generated was pancake ice formed in the wave fields. Heat flux measurements (Guest, 2021) suggested a 50% enhancement when sea spray is generated by the breaking waves in the open water sections of the polynya. Two methods are used to determine the enhancement of ice production by wave-generated pancake ice and sea spray heat flux enhancement in the coastal polynyas. Wave spectra from high resolution satellite radar imagery obtained contemporaneously with the SWIFT buoy wave spectra are compared to see if the high-frequency spectra indicative of breaking waves and sea spray can be determined (or parameterized) from the satellite imagery. Second, we examine whether general principles of wind and waves (e.g. the Beaufort scale) can be used in this coastal polynya case to determine a threshold wind speed for breaking waves and sea spray from winds measured at an automatic weather station near the TNB polynya. Estimated ice production rates are compared with previous estimates published from the field measurements. From these comparisons, we evaluate whether ice production in coastal polynyas can be estimated from remote sensing or from the winds in coupled air-ice-ocean models.
Year: 2022