Preprints
https://doi.org/10.5194/tc-2022-125
https://doi.org/10.5194/tc-2022-125
 
30 Aug 2022
30 Aug 2022
Status: this preprint is currently under review for the journal TC.

The diurnal evolution of oceanic boundary layer beneath early-frozen landfast ice in Prydz Bay, East Antarctica

Haihan Hu1,2, Jiechen Zhao3,4, Petra Heil5, Jingkai Ma6, Fengming Hui1,2, and Xiao Cheng1,2 Haihan Hu et al.
  • 1School of Geospatial Engineering and Science, Sun Yat-Sen University, Guangzhou 510275, China
  • 2Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China
  • 3Qingdao Innovation and Development Base (Centre) of Harbin Engineering University, Qingdao, 266500, China
  • 4College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China
  • 5Australia Antarctic Division & Australian Antarctic Programmer Partnership, Private Bag 80, Hobart TAS 7001, Australian
  • 6Key Laboratory of Research on Marine Hazards Forecasting, National Marine Environmental Forecasting Centre, Beijing 100081, China

Abstract. The ice–ocean boundary layer parameters are one of the main drivers of sea ice mass balance in the Polar Regions. To investigate the oceanic contribution to the landfast ice evolution, an integrated ocean observation system, including Acoustic Doppler Velocimeter, COMPACT-CTD, and Sea Ice Mass Balance Array, was deployed near Zhongshan Station in Prydz Bay, East Antarctica. The minute-resolution of ocean temperature, salinity, density, current, and heat flux from 16 to 23 April, 2021 were obtained and analysed. The results showed that ocean temperature experienced a jump increase, from -1.59±0.03 °C during 16–19 April to -1.47±0.07 °C during 20–23 April, which may relate to the tide transform from semi-diurnal to diurnal. Ocean salinity and density showed a gradual trend increasing by 0.013 psu day-1 and 0.009 kg m-3 day-1, respectively, related to the salt rejection of ice bottom freezing. The mean ocean velocity was 3.13±1.63 cm s-1 and 34 % of the current directions accounted to the northwest. Oceanic heat flux was estimated by the bulk parameterization method and residual energy method, which were 32.26±18.07 W m-2 and 34.95±17.52 W m-2, averaged for the study period respectively. Oceanic heat flux showed a large increase during 20–23 April, which shut down ice growth and resulted in 2 cm melting at the ice bottom. The high frequency of ocean observations allows us to deeply investigate diurnal changes of oceanic regimes and understand their influences on sea ice evolution.

Haihan Hu et al.

Status: open (until 30 Oct 2022)

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Haihan Hu et al.

Haihan Hu et al.

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Short summary
The oceanic characteristics beneath sea ice affects significantly the ice growth and melting. Based on the minute-scale observations of the ocean-ice boundary layer in the Prydz Bay, East Antarctica, this study analyzed the diurnal variation of oceanic parameters, and found some interested results from the detailed processes. For example, the change of tide phases raised ocean temperature and further the ocean-to-ice heat flux, causing an observed ice melting in the cold winter.