Date (Creation)

2020-08-31

Date (Publication)

2020-08-31

Credit

IMAS Honours Student Program 2019-2020

Status

Completed

Temporal resolution

P0Y0M1DT0H0M0S

Topic category

• Oceans

Maintenance and update frequency

Not planned

Keywords (Theme)

• BUOYANCY
• VERTICAL VELOCITY
• ERTEL POTENTIAL VORTICITY
• UPPER OCEAN

NASA/GCMD Keywords, Version 8.5

• EARTH SCIENCE | OCEANS | OCEAN PRESSURE | SEA LEVEL PRESSURE
• EARTH SCIENCE | OCEANS | OCEAN CHEMISTRY | OXYGEN
• EARTH SCIENCE | OCEANS | OCEAN TEMPERATURE | WATER TEMPERATURE
• EARTH SCIENCE | OCEANS | SEA SURFACE TOPOGRAPHY | SEA SURFACE HEIGHT
• EARTH SCIENCE | OCEANS | SALINITY/DENSITY
• EARTH SCIENCE | OCEANS | SALINITY/DENSITY | PYCNOCLINE
• EARTH SCIENCE | OCEANS | OCEAN CIRCULATION | WATER MASSES
• EARTH SCIENCE | OCEANS | OCEAN CIRCULATION | UPWELLING/DOWNWELLING
• EARTH SCIENCE | OCEANS | OCEAN CIRCULATION | OCEAN MIXED LAYER
• EARTH SCIENCE | OCEANS | OCEAN CIRCULATION | FRONTS

Australian and New Zealand Standard Research Classification (ANZSRC): Fields of Research

• Physical Oceanography

Keywords (Theme)

• time
• latitude
• longitude
• water pressure
• in situ temperature
• practical salinity
• dissolved oxygen consetration
• conservative temperature
• absolute salinity
• potential density
• depth
• mixed layer depth
• dissolved oxygen saturation
• temperature anomaly
• salinity anomaly
• density anomaly
• oxygen anomaly
• buoyancy
• buoyancy anomaly
• horizontal buoyancy gradient
• distance
• circumpolar deep water index
• Coriolis frequency
• buoyancy (Brunt-Vaisala) frequency squared
• Richardson Number
• Ertel potential vorticity
• vertical velocity
• Vertical shear
• along front velocity
• cross-front velocity

Language

English

Character encoding

UTF8

Supplemental Information

McDougall, TJ & Barker, PM 2011, 'Getting started with TEOS-10 and the Gibbs Seawater (GSW) Oceanographic Toolbox', SCOR/IAPSO WG127, p. 28, ISBN 978-0-646-55621-5.

Content type

Physical measurement

Description

Triaxus deployed time

Name

time

Name

time

Name

second (s)

Description

Triaxus latitude

Name

latitude

Name

lat

Name

Degrees(deg)

Description

Triaxus longitude

Name

longitude

Name

lon

Name

Degrees(deg)

Description

Triaxus, Seabird SBE911 CTD 25 sensor

Name

water pressure

Name

p

Name

Decibars (dbar)

Description

Triaxus

Name

in situ temperature

Name

T

Name

Degrees Celsius (degC)

Description

Triaxus

Name

practical salinity

Name

S

Name

Practical Salinity Unit (PSU)

Description

Triaxus

Name

dissolved oxygen consetration

Name

O

Name

Milligrams per kilogram (mg/kg)

Description

Triaxus, GSW toolbox

Name

conservative temperature

Name

CT

Name

Degrees Celsius (degC)

Description

Triaxus, GSW toolbox

Name

absolute salinity

Name

SA

Name

grams per kilogram (g/kg)

Description

Triaxus, GSW toolbox

Name

potential density

Name

sigma0

Name

kilograms per stere (kg/m3)

Description

GSW toolbox

Name

depth

Name

depth

Name

meter (m)

Description

Density increase was 0.02 kg/m3 with reference to a near-surface density value at 10 m depth.

Name

mixed layer depth

Name

mld

Name

meter (m)

Description

GSW toolbox

Name

dissolved oxygen saturation

Name

O2sat

Name

1

Description

CT

Name

temperature anomaly

Name

T_anom

Name

Degrees Celsius (degC)

Description

absolute salnity

Name

salinity anomaly

Name

S_anom

Name

grams per kilogram (g/kg)

Description

potential density

Name

density anomaly

Name

sigma0_anom

Name

kilograms per stere (kg/m3)

Description

dissolved oxygen

Name

oxygen anomaly

Name

O_anom

Name

Milligrams per kilogram (mg/kg)

Description

along-track buoyancy

Name

buoyancy

Name

b

Name

s−2

Description

along-track buoyancy

Name

buoyancy anomaly

Name

b_anom

Name

s−2

Description

along-track derivative of buoyancy

Name

horizontal buoyancy gradient

Name

b_grad

Name

s-3

Description

distance from the PF center

Name

distance

Name

dis

Name

meter (m)

Description

the profiles where have CDW

Name

circumpolar deep water index

Name

cdw_index

Name

/

Name

Coriolis frequency

Name

f

Name

/

Description

GSW toolbox, smoothed in a moving weighted average for the data in 9 dbar bins

Name

buoyancy (Brunt-Vaisala) frequency squared

Name

Nsquared

Name

s-2

Description

smoothed in a moving weighted average of 9 dbar vertically

Name

Richardson Number

Name

Ri

Name

/

Description

smoothed in a moving weighted average of 9 dbar vertically

Name

Ertel potential vorticity

Name

FPV

Name

s-3

Description

derived from SADCP and Triaxus data

Name

vertical velocity

Name

w

Name

meters per second (m/s)

Description

along the PF direction

Name

Vertical shear

Name

dus_dz

Name

m/s

Description

horizontal velocity

Name

along front velocity

Name

us

Name

m/s

Description

horizontal velocity

Name

cross-front velocity

Name

vs

Name

m/s

Distribution format

• MATLAB FILE

OnLine resource

DATA ACCESS - IN2018_V05_Triaxus [explore all files]

Statement

1. Satellite data Sea surface height (SSH) gridded data were obtained from the DUACS (Data unification and Altimeter combination system) products over the Southern Ocean region [146° E, 158° E], [52.5° S, 57.5° S] during the Southern Hemisphere spring from October 16 to November 16, 2018. The satellite dataset has daily SSH data, in a 0.25° × 0.25° spatial grid, encompassing the 16° longitude × 5° latitude region. The absolute dynamic topography (adt) that is the SSH above geoid was used to identify the core of the PF meander. The adt is obtained from the calculation: adt=sla+mdt, where sla is sea level anomaly and mdt is mean dynamic topography. 2.In situ observations: voyage data a. Triaxus data The Triaxus instrument was towed behind the ship and equipped with the Seabird SBE911 CTD 25 sensor to record pressures, conductivity and temperature data. Other sensors were also installed to collect other hydrologic data like dissolved oxygen. Pressure, conductivity and temperature data were calculated using calibration factors provided by Sea-Bird and calibrations provided by CSIRO. The data were processed by automated QC to remove spikes and out-of-range values. Triaxus profiles were limited to 300 m depth with a vertical resolution of 1 dbar and an approximate 0.9-1.5 km lateral spacing between vertical Triaxus casts (averaged every 5 minutes). The oxygen data was directly measured from the dissolved oxygen sensors. The salinity was the absolute salinity. The temperature was converted to the conservative temperature at each depth. The potential density was derived from absolute salinity and conservative temperature. The Gibbs-SeaWater (GSW) Oceanographic Toolbox in MATLAB was applied for evaluating these thermodynamic properties (absolute salinity, conservative temperature, potential density and in situ density) of seawater. b. Shipboard ADCP data Shipboard Acoustic Doppler Current Profiler (SADCP) mounted on the ship hull was used to determine absolute currents in 8-m-depth bins and approximately at a 1 km lateral scale (averaged every 5 minutes) in the upper ocean in coordination with accurate heading and navigation data. Narrowband data collection was used both for the RDI Ocean Surveyor 150 kHz ADCP and the RDI Ocean Surveyor 75 kHz ADCP. The drop keel was at 6 m below the waterline during the voyage. In this study, the 150 kHz RDI ADCP measured velocities from 18 m to 500 m depth, and the data output was averaged every 5 minutes. The horizontal velocity has two components, with u being defined as the West-East (zonal) velocity component and v being defined as the North-South (meridional) velocity component. There was a spatial offset between the SADCP on the ship and the Triaxus that is towed behind the ship, which was adjusted by shifting the timestep of the SADCP back by 5 minutes. c. CTD data The voyage obtained 77 full-depth CTD casts with full hydrochemistry along 9 cross-front transects. The CTD was fitted with various sensors to collect the temperature, conductivity, pressure, dissolved oxygen and fluorescence data in a high vertical resolution. The CTD frame held 36 Niskin bottles that allowed water samples to be collected from different depths during the CTD deployments. The various parameters in the water samples, including salinity, dissolved oxygen, phosphate, silicate, nitrate plus nitrite and ammonium, were processed and analysed to calibrate the data directly on the ship.

Hierarchy level

Dataset

Resource scope

Dataset

Title

ISO 19115-3:2018