Data

Your access to IMOS Ocean Glider data discovery and exploration is through the Australian Ocean Data Network (AODN) Portal.

The GLIDERSCOPE software is available for data visualisation.

Autonomous ocean gliders can be built relatively cheaply, are controlled remotely and reusable allowing them to make repeated subsurface ocean observations at a fraction of the cost of conventional methods. They are vehicles that carry a different suite of sensors thourgh the area of interest providing storage and communication of data sets. The data retrieved from the IMOS glider fleet is contributing to the study of the major boundary current systems surrounding Australia and their links to coastal ecosystem processes. Both the Slocum and Seagliders are equipped with measure conductivity, temperature, dissolved oxygen, phycoerythrin, chlorophyll-a, turbidity, and dissolved organic matter against position and depth. All of the variables are available in real time during the deployment and quality controlled delayed mode data is available within four months approximately of the glider being retrieved. The table below shows the parameters measured by the IMOS gliders.

Parameters measured as timeseries by sensors on IMOS ocean gliders

code

standard_name / long_name (for non-CF)

observation_type

units

 

CNDC

 

 

sea_water_electrical_conductivity

 

measured

 

S m-1

 

 

TEMP

 

 

sea_water_temperature

 

measured

 

Celsius

 

PRES

sea_water_pressure

measured

dbar

 

BBP

 

particle_backscattering_coefficient

 

 

computed

 

m-1

 

PSAL

 

 

sea_water_salinity

 

computed

 

1e-3

 

DOX1

 

mole_concentration_of_dissolved_molecular_oxygen_in_sea_water

measured (SG) computed (SL)

 

umol l-1

 

DOX2

 

moles_of_oxygen_per_unit_mass_in_sea_water

 

computed

 

umol l-1

 

CPHL

 

 

mass_concentration_of_chlorophyll_in_sea_water

 

computed

 

mg m-3

 

 

CDOM

 

 

concentration_of_coloured_dissolved_organic_matter

 

computed

 

1e-9

 

VBSC

 

volumetric_scattering_function

 

computed

 

m-1 sr-1

 

 

IRRADxxx*

 

 

downwelling_spectral_irradiance_in_sea_water_beamn+

 

computed

uW cm-2 nm-1

 

HEAD

 

vehicle_heading

 

measured

 

Degrees

 

UCUR

 

 

eastward_sea_water_velocity

 

computed

 

m s-1

 

VCUR

 

 

northward_sea_water_velocity

 

computed

 

m s-1

 

UCUR_GPS

 

 

eastward_surface_sea_water_velocity

 

computed

 

m s-1

 

VCUR_GPS

 

 

northward_surface_sea_water_velocity

 

computed

 

m s-1

 

PHASE

 

 

glider_trajectory_phase_code

 

computed

 

1

 

PROFILE

 

 

glider_trajectory_profile_number

 

computed

 

1

 

 

indicates a non-CF parameter. These parameters do not have associated standard names. Instead, long_name is listed.

* the codes are wave length dependant, different on each sensor. In total we have 7 generic wavelengths, i.e. ANFOG data contain the following parameters: IRRAD443, IRRAD490, IRRAD555, IRRAD670, IRRAD456, IRRAD 470 and IRRAD520. For instance for platform SL210, the four irradiance codes are: IRRAD443, IRRAD490, IRRAD555 and IRRAD670. The real wavelength, that is sometimes slightly different from the generic one (and differs from one sensor SN to another), is specified in the ‘comment’ attribute of the corresponding parameter.

+ n indicates the beam number, e.g. 1, 2, 3 or 4.

The use of the high-resolution repeat sampling possible with ocean gliders in the continental shelf have revealed dense pools of shelf water. These dense water pools are due to sea temperatures being significantly warmer than air temperatures during winter, with the ocean losing heat to the atmosphere. Cooled surface water sinks as a consequence of its density increasing. In shallow water, where there is no deep reservoir of heat, the whole water column can cool down nearly to air temperature. Once dense enough, the cold coastal water slides down the sloping sea floor as a ‘gravity current’ to form a distinct layer underneath the warmer offshore waters. Slocum glider missions around Australia (Spencer Gulf, Two Rocks in WA, the Kimberley and Yamba NSW) have all just recently encountered dense shelf water pools.

Spencer Gulf, Density, May 28 - June 2, 2015

In addition to the potential transport properties of DSWC, the glider surveys have indicated that the formation of these dense water masses may have important impacts on nearshore phytoplankton production.

Cross-shelf profiles, temperature, salinity, and phytoplankton chlorophyll fluorescence along the Two Rocks transect in April 2009.

Time series data collected by the Seaglider deployment between Perth Canyon and Jurien Bay during 2010 show the Seaglider making 6 encounters with the Leeuwin Current as identified through the warmer, lower salinity (therefore lower density) water. The Leeuwin current was also higher in fluorescence. The higher dissolved oxygen values are again associated with the Leeuwin Current.

Time series of Seaglider data: (a) temperature; (b) salinity; (c) density; (d) chlorophyll fluorescence; and, (e) dissolved oxygen obtained between Perth Canyon and Jurien Bay in 2010