Ross Ice Shelf Cavity Ocean Data
|Temporal extent||2017-12-03 -2018-02-27|
|Author(s)||Stevens Craig1, Brewer Mike1, Grant Brett1|
|Affiliation(s)||1 : NIWA, New Zealand|
|Keyword(s)||ice shelf cavity, Ross Ice Shelf, ocean mooring, hydrography, CTD profile, current meter, microstructure profile|
Here we provide data from the Ross Ice Shelf ocean cavity. Location - The HWD2 Camp was established in October of 2017 at 80o 39.497’S, 174o 27.678’E where the ice is moving seaward at around ~600 m a-1 and is sourced from the Transantarctic Mountains. Profiling Instruments - Profiling was primarily conducted with an RBR Concerto CTD (conductivity-temperature depth) profiling instrument, and this was cross-calibrated against irregular profiles with an RBR Duet (pressure and temperature only), a SBE37 MicroCat CTD as well as moored SBE37 MicroCat CTDs. The RBR unit is small and has suitable sensor capability (temperature and conductivity accuracies of ±0.002°C and ±0.003 mS cm-1). Its conductivity cell design is not prone to fouling by ice crystals, making it ideal for work in the sometimes crystal-laden borehole conditions. We were inconsistent in how we mounted the CTD on its protective frame and this appeared to make small difference in the conductivity signal (resulting in an ~0.03 psu variation). This was post-corrected based on the essentially invariant mooring data from the lower water column as well as SBE37 cross-calibration profile data. Because of the potential for sediment contamination of the sensors, the profiles were mostly conservative in their proximity to the sea floor. On several occasions, profiles were conducted all the way to the sea floor. The temperature and salinity are presented in EOS-80 in order to compare with available data. Eighty three profiles are provided here (ctd_HWD2_*.dat). In addition, limited microstructure profiling was conducted to provide insight into some of the mixing details.
|Acknowledgements||This research was facilitated by the New Zealand Antarctic Research Institute (NZARI) funded Aotearoa New Zealand Ross Ice Shelf Programme and the Victoria University of Wellington Hot Water Drilling initiative. We thank the Victoria University of Wellington Hot Water Drilling Team led by Alex Pyne and Darcy Mendeno. Jeff Dunne, Lana Hastie and Kurt Roberts made it possible to work at camp. Dan Lowry, Gavin Dunbar and Gary Wilson provided field assistance and invaluable discussions. Brett Grant, Pete de Joux and Nick Eaton developed and mobilised the instrumentation. Logistics support and flights were provided by Antarctica New Zealand and Kenn Borek Air. Additional support was provided by NIWA Strategic Science Investment Funding, the Deep South National Science Challenge and the Antarctic Science Platform. Further details in: Stevens C, Hulbe C, Brewer M, Stewart C, Robinson N, Ohneiser C and Jendersie J, 2020. Ocean mixing and heat transport processes observed under the Ross Ice Shelf controls its basal melting, accepted PNAS, May 2020.|
Eighty three profiles are provided here (ctd_HWD2_*.dat) using RBR Concerto CTD (conductivity temperature depth).
Five files are provided here (HWD2_Init_rcm*.dat4). The mooring instruments at HWD2-A comprised 5 Nortek Aquadopp single point current meters in titanium housings reporting to the surface (30-minute interval, Table SI-Three) via an inductive modem to a Sound-9 data logger and Iridium transmitter. The current meter measurements were corrected to account for the 138o magnetic declination offset (i.e. the south magnetic pole is to the north-west of the field site).
A single microstructure profile segment is included (VMP_HWD2.dat).
Details in: Stevens C, Hulbe C, Brewer M, Stewart C, Robinson N, Ohneiser C and Jendersie J, 2020. Ocean mixing and heat transport processes observed under the Ross Ice Shelf controls its basal melting, accepted PNAS, May 2020.