Interfaces and Ocean Heat Flux derived from SIMBA_2015a and SIMBA_2015f data during N-ICE campaign in winter 2015.

Date 2015-07-15
Temporal extent 2015-01-15 -2015-03-16
Author(s) Sennechael NathalieORCID1, Provost ChristineORCID1
Affiliation(s) 1 : Laboratoire LOCEAN-IPSL Sorbonne Université (UPMC, Univ. Paris 6)-CNRS-IRD-MNHN, Paris, France
DOI 10.17882/59709
Publisher SEANOE
Keyword(s) sea ice, snow, ice growth, basal melt, flooding, snow-ice, mass balance
Abstract

We defined the interfaces between the air/snow, snow/ice, and ice/ocean and calculated the ocean heat flux for two SIMBA recordings (SIMBA2015a and SIMBA_2015f) of repeated temperature profiles at 6h interval and 2cm vertical resolution, during N-ICE 2015 experiment floe1.


  • The snow/ice interface is derived from the sharp contrast in the diffusivity proxy values between both media. The snow/ice interface does not change except for slush formation associated with flooding events.

  • The air/snow interface is calculated using simultaneous information from the vertical gradient of the temperature and the standard deviation over 24, 48, and 72 h period. Snow accumulation of more than 10 centimeters happened at different time for the 2 SIMBA.


  • The ice/ocean interface is estimated from temperature profiles alone since the winter sea-ice remains colder than the ocean. The ocean just below the ice is at or just above the freezing temperature (estimated from a near surface conductivity-temperature-depth (CTD) sensor see Koenig et al. [2016]). The method detects (1) the first sensor, downward of the snow/ice interface, with a temperature above the ocean freezing temperature and (2) the last sensor in the ice with a temperature below the mean ocean temperature by at least twice the ocean temperature standard deviation in that profile. The ice/ocean interface is then defined as half way between the last sensor in the ice and the first sensor in the ocean. Note it take 3-4 days for the deployment hole to refreeze. Then the ice thickness remains constant up to 20 February when floe1 breaks. Simba_2015f stops working and SIMBA_2015a features basal melt events corresponding to temperature changes in the ocean.

The consistency of the 3 interfaces estimate is validated with the thermal diffusivity proxy and the vertical and temporal derivatives of temperature.


  • The ocean heat flux is derived from the latent heat flux which is directly proportional to the change in time of the ice/ocean interface depth and the conductive heat flux in the lower portion of the ice estimated 6 cm above the ice/ocean interface. The ocean heat flux values for SIMBA_2015a and SIMBA2015f range from -50 to 350 W/m2, and -50 to 150 W/m2 respectively, while the basal melt events associated with ocean temperature increase stand out in SIMBA_2015a.

 

The SIMBA data are available through the Norwegian Polar Institute’s data center (https://data.npolar.no/dataset/6ed9a8ca-95b0-43be-bedf-8176bf56da80) and the method of interface detection is thoroughly described in Provost et al. (2017). Note that all time series have been smoothed with a 36-h running mean.

 

Provost, C., N. Sennechael, J. Miguet, P. Itkin, A. Rosel, Z. Koenig, N. Villacieros-Robineau, and M. A. Granskog (2017), Observations of flooding and snow-ice formation in a thinner Arctic sea-ice regime during the N-ICE2015 campaign: Influence of basal ice melt and storms, J. Geophys. Res. Oceans, 122, 7115–7134, doi:10.1002/2016JC012011.

Licence CC-BY-NC
Acknowledgements Equipment and participation to the N-ICE2015 Ice camp (organized by the Norsk Polar Institute, Norway on board R.V. Lance, Granskog et al., 2017) were funded under EQUIPEX IAOOS (Ice Atmosphere Ocean Observing System) (ANR-10-EQPX-32-01).
Sensor metadata

Both ice instruments (SIMBA_2015a and SIMBA_2015f) are SIMBAs (SAMS Ice Mass Balance for the Arctic). A SIMBA comprises a GPS and a 5 m long chain cable hanging through air, snow, sea-ice and ocean. The chain comprises solid-state sensors located every 2 cm measuring temperature at approximately 0.18°C accuracy (resolution 1/16°C). The SIMBA also features a heating mode which can be used to discriminate between different media, especially between snow and ice [Jackson et al., 2013].

Data
File Size Format Processing Access
Interfaces and Ocean Heat Flux derived from SIMBA_2015a data during N-ICE 2015 campaign North of Svalbard 14 KB NC, NetCDF Processed data Open access
Interfaces and Ocean Heat Flux derived from SIMBA_2015f data during N-ICE 2015 campaign North of Svalbard 7 KB NC, NetCDF Processed data Open access
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How to cite 

Sennechael Nathalie, Provost Christine (2015). Interfaces and Ocean Heat Flux derived from SIMBA_2015a and SIMBA_2015f data during N-ICE campaign in winter 2015. SEANOE. https://doi.org/10.17882/59709