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Sea Ice Mass Balance in the Antarctic - Physical Oceanography

Entry ID: SIMBA_Physical_Oceanography

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Summary

Abstract: Between September 25 and October 25 there were a total of 69 CTD casts with the NBP’s 24 bottle rosette system deployed from ship’s Baltic room (‘Baltic CTD’) and 14 casts with a sensor-only CTD package deployed from the stern A-frame (‘Stern CTD’) when conditions or work on the ice did not allow starboard-side access to the water. The Baltic room system includes a 24-place rosette frame with ... bullister-type rosette bottles of slightly less than 10 liter capacity each. Data acquisition for these two CTD systems as well as the Trace Metal Clean (TMC) CTD took place on an NBP Windows XP computer running Sea-Bird’s Seasave software. Electronics problems and computer software freeze-ups required repeated re-terminations of the CTD cables and at least one change of CTD computer during the course of NBP07-09. All three CTD packages included dual temperature, salinity, and oxygen sensors, while the Baltic and TMC packages additionally carried transmissometers, fluorometers, and PAR sensors (the latter being depth-rated to 1000m, it was removed from the Baltic CTD frame for deep casts). Additionally, dissolved oxygen (winkler method) and salinity values determined via laboratory analysis of water collected from rosette bottles following the Baltic and TMC casts were used to correct for any drift that may be detected in the cast data. Other laboratory analyses of water samples collected from rosette bottles included DMS, pH, total pH, DIC, total alkalinity, nutrients, and chlorophyll. Depending on water column characteristics such as temperature, salinity, and (later in the cruise / season), fluorescence, niskin bottles were triggered at various (between two and 23) depths during the CTD up-cast. Additional water sampling was conducted from the NBP’s uncontaminated seawater line, both for salinity analyses and for total CO2, which will be analyzed at the Lamont-Doherty Earth Observatory in conjunction with the ongoing Takahashi pCO2 surface observation project.

Our first three Baltic CTD casts to 500-550m were acquired over a north-south transect from southeast of Peter 1 Island (7016S), to the most southerly CTD location of the cruise (70 38 S). All three CTD casts showed characteristic winter profiles with a cold (-1.8C), fresh (33.96-34.02ppt) surface mixed layer down to 90m, 120m and 150m (from north to south), overlying warm (1.4-1.9C), salty (34.68-34.72ppt) Upper Circumpolar Deep Waters.

Purpose: Basic physical and chemical oceanography from CTD, trace metal and other bottle casts is generally poor in the Southern Ocean and particularly so in the ice-covered winter pack ice zone. This data set provides better information on the ocean beneath the ice pack in the Bellingshausen Sea than previously available.

Related URL

Link: VIEW PROJECT HOME PAGE

Geographic Coverage

(Click for Interactive Map)

Spatial coordinates

N: -61.85

S: -70.68

E: -64.05

W: -94.85

Temporal Coverage

Start Date: 2007-09-01

Stop Date: 2007-10-31

Location Keywords

CONTINENT > ANTARCTICA

GEOGRAPHIC REGION > POLAR

OCEAN > SOUTHERN OCEAN > BELLINGSHAUSEN SEA

Science Keywords

OCEANS > OCEAN CHEMISTRY > OXYGEN

OCEANS > SALINITY/DENSITY > SALINITY

ISO Topic Category

CLIMATOLOGY/METEOROLOGY/ATMOSPHERE

ENVIRONMENT

OCEANS

Platform

SV > Snow Vehicle

GPS > Global Positioning System Satellites

R/V NBP > R/V Nathaniel B. Palmer

Instrument

CTD > Conductivity, Temperature, Depth

Project

NSF/OPP > Office of Polar Programs, National Science Foundation

IPY > INTERNATIONAL POLAR YEAR

Access Constraints None

Data Set Progress

IN WORK

Originating Center

Laboratory for Remote Sensing and Geoinformatics UTSA

Data Center

National Snow and Ice Data Center

Data Center URL: http://nsidc.org

Data Center Personnel
Name: STEPHEN ACKLEY Phone: +1 1 210 341 6556 Email: sackley at pol.net, Stephen.ackley at utsa.edu Contact Address: 118 W Castle Ln City: San Antonio Province or State: Texas Postal Code: 78213 Country: USA

Data Center Personnel
Name: NSIDC USER SERVICES Phone: +1 (303) 492-6199 Fax: +1 (303) 492-2468 Email: nsidc at nsidc.org Contact Address: National Snow and Ice Data Center CIRES, 449 UCB University of Colorado City: Boulder Province or State: CO Postal Code: 80309-0449 Country: USA