How ACORN data is shown on the IMOS OceanCurrent website

David Griffin

CSIRO Marine and Atmospheric Research

Purpose of OceanCurrent

• To provide a diverse range of user groups with a quick look at a wide range of data types – not the details of any.

• A (not exclusive) emphasis on now. • National coverage. Not tied to any node or facility.• Not interactive. Not a data portal. Just maps and words.• Interpret the data, explain the methods. Integrate the MOS.• Exercise the data system. Identify data mgt inconsistencies.• Eventually: statistical products, not just snapshots and

animations

Use of ACORN

• Went ‘live’ on 8 June 2012, ie plots update automatically• Showing ROT, SAG, BONC, COF and CBG on top of SST,

altimetry, drifters, ANMN and soon: gliders and chlor-a • TURQ is on a secret page because the data look wrong• COF and BONC have lesser problems• CBG is OK but the tides are strong and coverage intermittent• ROT provides the best eye candy – hence the Ocean News

item.

Stumbling blocks

• Several ‘inconveniences’ (for users) could be removed:• Hourly data stored 1 record per file -> 8 hours to read a year.

• Seb has now made monthly files with ~24*30 records –should be much faster to read.

• QC flags not useful (and too numerous)• CODAR:

• hidden in a folder called ‘Sea state’ – but no wave data.

• No TIME dimension. (Time is an attribute, not a variable).

• List of points. User must infer the grid.

• Many files with no data

• Main issue: gappiness. We were warned.

TURQ data (northern array) are clearly wrong:

Conclusion

• Congratulations to those who have got us to where we are now!• ACORN has a wide range of practical as well as research uses. • Some issues need addressing:• File formats• Calibration• De-tiding. Files could include tidal current predictions,

especially for CBG. In turn, analyses of ACORN data will improve those predictions.

• Need longer range. Neptune system for GAB/Browse/NWS?• Bluelink will be using ACORN mostly for validation. But Au-

focussed projects will assimilate the data into models – and then be hungry mouths.

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Thankyou

Data reading

• We use toolsIU.jar (via Matlab’s java virtual machine) for reading the files from the server. FFI: http://www.unidata.ucar.edu/software/netcdf-java/documentation.htm

• The harder job is knowing 1) what files are there and 2) what’s in them.

• To solve (1) we use Laurent Besnard’s List_NC_recur.m• To solve (2) we simply rummage the metadata with a browser.