CARS home page is now http://www.cmar.csiro.au/cars. That page gives access to the latest version (CARS2009).

The penultimate version of CARS is described at CARS2006.

The page below describes the superceded earliest version, called CARS2000.

CSIRO Atlas of Regional Seas (CARS2000)

On this page: Using CARS | Software | Access | About CARS | References | Sample plots

CARS is a digital atlas of seasonal ocean water properties, covering the seas around Australia. The six water properties mapped are temperature, salinity, oxygen, nitrate, silicate, phosphate.

Using CARS

Each water property atlas is available separately. CARS is on CSIRO standard depth levels: version 2 (56 levels) for CARS2000 and version 3 (79 levels) for CARS2005. CARS2000 is on a .5X.5 degree grid in the region 30E - 200E, 70S - 10N. CARS2005 is on a .5X.5 degree grid in the region 0E - 360E, 70S - 26N (10N only in the Atlantic). The following variables are likely to be most useful:

Variables

Name	Description
depth	depths of the 56 or 79 mapping levels (in metres)
depth_timefit	depths of the 35 levels for which seasonal cycles are estimated (these are just levels 1 to 35 of "depth") ( CARS2000 )
depth_ann	depths of the levels for which annual cycles are estimated ( CARS2005 )
depth_semiann	depths of the levels for which semiannual cycles are estimated ( CARS2005 )
mean	estimate of mean value
an_cos	cosine of annual sinusoids fitted for depth levels 1 to 35 (0 to 1000m)
an_sin	sine of annual sinusoids
sa_cos	cosine of semiannual sinusoids fitted for depth levels 1 to 35 for Temperature and Salinity maps
sa_sin	sine of semiannual sinusoids
lat,lon	grid point locations

Example

To construct the temperature map for mid-February at 200m depth:

Extract variable "depth" and find that 200m is at level 17.

Extract at level 17, and in the region required:

mean

an_cos

an_sin

sa_cos

sa_sin

Evaluate at day-of-year 45 (mid February)

t = 2pi x 45/366

feb = mean + an_cos*cos(t) + an_sin*sin(t) + sa_cos*cos(2*t) + sa_sin*sin(2*t)

Software (a limited package of access routines)

Many popular software products have interfaces or library routines to interrogate and extract data from netCDF files.

The only assistance we are able to provide is a small package of unsupported Matlab access routines which require local installation of the Matlab-netcdf "toolbox". This can be downloaded along with the CARS data.

Matlab functions for CARS access

Name	Use
getchunk	extracts a 3D chunk
getmap	extracts a single depth layer or horizontal slice
get_clim_casts	extract vertical profiles at the lats/longs and optionally time of year
get_clim	alternative to get_clim_casts
atday	evaluate the mean and temporal harmonics at a particular day-of-year.
atdaypos	as for atday, but also interpolates to desired locations
dep_csl, csl_dep	convert between depth (m) and CSIRO standard depth levels (CSL)

Accessing CARS

CARS2000 is provided freely via web download.

If publications arise from work that makes use of CARS, please send us a copy, via email

Jeff.Dunn@csiro.au

or to:

Jeff Dunn

CSIRO Marine Laboratories

GPO Box 1538

Hobart, TAS, 7000, Australia

Before retrieving data please read the conditions below and acknowledge that you accept them. Acceptance of the conditions will activate the download page.

Conditions

The User acknowledges that the Product was developed by CSIRO for its own research purposes. The CSIRO will not therefore be liable for interpretation of or inconsistencies, discrepancies, errors or omissions in any or all of the Product as supplied.

Any use of or reliance by the User on the Product or any part thereof is at the User's own risk and CSIRO shall not be liable for any loss or damage howsoever arising as a result of such use.

The User agrees that whenever the Product or imagery/data derived from the Product are published by the User, the CSIRO Marine Laboratories shall be acknowledged as the source of the Product.

The User agrees to indemnify and hold harmless CSIRO in respect of any loss or damage (including any rights arising from negligence or infringement of third party intellectual property rights) suffered by CSIRO as a result of User's use of or reliance on the Data.

If you accept these conditions please enter the information below for our records, and press Accept.

About making CARS

Data sources

The atlas is derived from two major datasets, interpolated onto standard depths:

• NODC World Ocean Atlas 1998 hydrographic data (NODC home page)
• CSIRO archive of Australian hydrographic data

Data was screened for duplicates and bad positions, outliers to local t-s relations in density coordinates, and outliers of residuals to intermediate mappings.

Mapping method

The mapping algorithm is adapted from the weighted least-squares quadratic smoother, known as a "loess" smoother. Quadratics were fitted in horizontal and vertical coordinates, with bathymetry-influenced weighting. For nutrient maps, annual harmonics were simultaneously fitted down to 1000m. For temperature and salinity (where data density was much higher), semi-annual harmonics were also fitted for all maps down to 1000m.

For every mapped point, a (zonally stretched) radius was calculated that provided 400 data points at that depth. Other points were used from one standard depth above and below, if their combined XY-radius, Z-distance, and bathymetry-weight-distance fell within the 400-point horizontal radius. That is, in ocean of uniform depth, the data source region roughly forms a 3 dimensional ellipse. An important characteristic of this type of mapping is that length scales are automatically adapted to data density, providing maximum resolution in areas of high sample density.

A value is provided everywhere the ocean is deep enough, and one gridpoint landwards of each depth "shoreline" (this allows interpolation between gridpoints to locations near the shorelines).

References

Ridgway K.R., J.R. Dunn, and J.L. Wilkin, Ocean interpolation by four-dimensional least squares -Application to the waters around Australia, J. Atmos. Ocean. Tech., Vol 19, No 9, 1357-1375, 2002

Dunn J.R., and K.R. Ridgway, Mapping ocean properties in regions of complex topography, Deep Sea Research I : Oceanographic Research, 49 (3) (2002) pp. 591-604

Selected images from CARS2000

These gif images are also freely available by anonymous ftp from ftp.marine.csiro.au in directory /pub/dunn/CARS2000/gifs/.