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Cold Spice: Double Diffusion Generated by Vertical Ice Walls at Erebus Ice Tongue and Drygalski Ice Tongue, Antarctica

Federal Geographic Data Committee (FGDC) Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator: Unknown
Publication_Date: Unknown
Title: Cold Spice: Double Diffusion Generated by Vertical Ice Walls at Erebus Ice Tongue and Drygalski Ice Tongue, Antarctica
Description:
Abstract:
“Ocean spice” refers to one of the great hidden mechanisms driving ocean missing. Large regions of the oceans are layered in such a way that differences in molecular characteristics between heat and the salt (technically called double diffusion) are sufficient to vigorously mix the seawater – but only in vertically confined layers. These layers form tendrils anywhere from 1 to 100 m thick and can extend for hundreds of kilometres. Yet we have few direct measurements of the rates of vertical mixing within and between these layers. It is likely that rates of mixing will differ by orders of magnitude within a few meters, or even mix in the opposite direction to “normal”. This process is seen in polar oceans where the interaction between seawater and melting ice (both sea ice and ice shelves) modulates ocean stratification and transport. In turn, stratification and transport strongly affect the combined climate-ecosystem. Here we will link field measurements of ocean spice generated by ice shelves with laboratory and computer models. The aim of the work is two-fold: better understanding of the details of this mixing and to fill in a key gap in predictive climate models. Antarctic ice shelf cavities are one of the last unknown geophysical domains. The Ross Ice Shelf Cavity alone contains ~120,000 cubic km (1.3x that of the North Sea), of essentially un-sampled ocean. Geophysical-scale fluid mechanical modelling has the potential to identify the dominant energy and material pathways, but only if this modelling is strongly informed by the correct mechanics. At these scales oceanic transport and diffusion are dominated by mixing near sharp topography. Very recent ocean observations from the front of the Ross Ice Shelf suggest that this might also be true for ice shelf cavities. Here we are using glacier tongues as an accessible proxy for the front of an ice shelf. We are looking at the downstream manifestation of this ice shelf water and how it is influenced by giant glacier tongues of which there are many along the Victoria Land Coast. Oceanic mixing processes in the lee of a floating glacier tongue, the Erebus Ice Tongue, McMurdo Sound, were investigated to inform geophysical-scale fluid mechanical modelling of ice shelves. The Erebus Ice Tongue was used as an accessible proxy for the front of an ice shelf. Ocean flow rates and rates of mixing (= turbulence), temperature and salinity were measured next to the Erebus Ice Tongue and an AUV and ROV was deployed to make measurements at depth. Four different acoustic current profilers generated velocity data extending right from just beneath the ice-ocean interface to the seafloor bed (340m). Turbulence profile data (VMP 500 profiler) was obtained in 24 hour bursts (a profile every 20 minutes) during spring and neap tides. The Drygalski Ice Tongue is the largest existing ice tongue remaining. Not only is it in the path of buoyant out flow from the Ross Ice Cavity it also heavily influences the Terra Nova Bay Polynya one of the key oceanographic features in the area. The main focus for the research was to determine flows beneath/next to glacier tongue, determine rates of ocean mixing and seek super cooling effects.
Purpose:
Not Available
Supplemental_Information:
REFERENCE: Stevens, C. L., Stewart, C. L., Robinson, N. J., Williams, M. J. M., and Haskell, T. G.: Flow and mixing near a glacier tongue: a pilot study, Ocean Sci., 7, 293-304, doi:10.5194/os-7-293-2011, 2011.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20101024
Ending_Date: 20120126
Currentness_Reference:Unknown
Status:
Progress: Complete
Maintenance_and_Update_Frequency: As needed
Spatial_Domain:
Description_of_Geographic_Extent:
Bounding_Coordinates:
West_Bounding_Coordinate: 166.446
East_Bounding_Coordinate: 166.446
North_Bounding_Coordinate: -77.7025
South_Bounding_Coordinate: -77.7025
Spatial_Domain:
Description_of_Geographic_Extent:
Bounding_Coordinates:
West_Bounding_Coordinate: 163.30923
East_Bounding_Coordinate: 163.30923
North_Bounding_Coordinate: -75.31655
South_Bounding_Coordinate: -75.31655
Keywords:
Theme:
Theme_Keyword_Thesaurus: GCMD SCIENCE PARAMETERS
Theme_Keyword_Thesaurus: GCMD PLATFORM
Theme_Keyword_Thesaurus: GCMD INSTRUMENT
Theme_Keyword_Thesaurus: ISO TOPIC CATEGORY
Theme_Keyword_Thesaurus: DATA SET LANGUAGE
Theme_Keyword: EARTH SCIENCE > CRYOSPHERE > GLACIERS/ICE SHEETS > ICE SHEETS
Theme_Keyword: EARTH SCIENCE > OCEANS > OCEAN CIRCULATION > OCEAN MIXED LAYER
Theme_Keyword: EARTH SCIENCE > OCEANS > OCEAN CIRCULATION > TURBULENCE
Theme_Keyword: EARTH SCIENCE > OCEANS > OCEAN CIRCULATION > WATER MASSES
Theme_Keyword: EARTH SCIENCE > OCEANS > SALINITY/DENSITY > CONDUCTIVITY
Theme_Keyword: EARTH SCIENCE > OCEANS > SALINITY/DENSITY > SALINITY
Theme_Keyword: EARTH SCIENCE > CRYOSPHERE > GLACIERS/ICE SHEETS > GLACIERS
Theme_Keyword: EARTH SCIENCE > OCEANS > SEA ICE > POLYNYAS
Theme_Keyword: FIELD INVESTIGATION
Theme_Keyword: FIELD SURVEYS
Theme_Keyword: CURRENT METERS
Theme_Keyword: CTD > CONDUCTIVITY, TEMPERATURE, DEPTH
Theme_Keyword: STICS > SUPRATHERMAL ION COMPOSITION SPECTROMETER
Theme_Keyword: ADCP > ACOUSTIC DOPPLER CURRENT PROFILER
Theme_Keyword: OCEANS
Theme_Keyword: ENGLISH
Place:
Place_Keyword_Thesaurus: GCMD
Place_Keyword: CONTINENT > ANTARCTICA > DRYGALSKI ICE TONGUE
Place_Keyword: CONTINENT > ANTARCTICA > EREBUS ICE TONGUE
Place_Keyword: CONTINENT > ANTARCTICA
Place_Keyword: GEOGRAPHIC REGION > POLAR
Access_Constraints: Not Available
Use_Constraints:
Not Available
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: CRAIG STEVENS
Contact_Position: INVESTIGATOR
Contact_Address:
Address_Type: Mailing and Physical Address
Address: NIWA
Address: Private Bag 14901
City: WELLINGTON
Postal_Code: 6021
Country: NEW ZEALAND
Contact_Voice_Telephone: 04 386 0476
Contact_Facsimile_Telephone: +64 4 386 2153
Contact_Electronic_Mail_Address: c.stevens@niwa.co.nz
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Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
2010/2011 research is stored at NIWA archive, UC-Davis Archive, UBC Canada Archive. 2011/2012 research is stored at NIWA secure archive, Italian PNRA archive. Shear microstructure profiles from beneath sea ice south of Drygalski Ice Tongue - only top 300 m whereas water column is ~ 700m. Some adcp data of top 100 m. If you require any further information please contact NIWA, Wellington.
Logical_Consistency_Report:
Not Available
Completeness_Report:
Not Available
Lineage:
Process_Step:
Process_Description:
Not Available
Process_Date: Unknown
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Spatial_Reference_Information:
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: NZ/NZAI/ANZ > Antarctica New Zealand, New Zealand Antarctic Institute, New Zealand
Contact_Person: CAROLINE MACLAURIN
Contact_Position: DATA CENTER CONTACT
Contact_Address:
Address_Type: Mailing and Physical Address
Address: Antarctica New Zealand
Address: Private Bag 4745
City: Christchurch 8140
Country: New Zealand
Contact_Voice_Telephone: (03) 358 0200
Contact_Facsimile_Telephone: (03) 358 0211
Contact_Electronic_Mail_Address: c.maclaurin@antarcticanz.govt.nz
Resource_Description: K132_2010_2012_NZ_1
Distribution_Liability:
Not Available
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: Not Available
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
http://www.antarcticanz.govt.nz/
Access_Instructions:
DATA CENTER URL
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
http://supercritical.civil.ubc.ca/%7Eefmweb/hamilt...
Access_Instructions:
GLACIER TOUNGES AND OCEAN MIXING
Fees: Not Available
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Metadata_Reference_Information:
Metadata_Date: 20120617
Metadata_Review_Date: 20120618
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: GCMD User Support Office
Contact_Organization: NASA Global Change Master Directory
Contact_Address:
Address_Type: Mailing and Physical Address
Address: Not Available
City: Lanham
State_or_Province: MD
Postal_Code: 20706
Country: USA
Contact_Voice_Telephone: Not Available
Contact_Electronic_Mail_Address: gcmduso@gcmd.gsfc.nasa.gov
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time
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