eReefs CSIRO Hydrodynamic model (Temperature, Salinity, Wind, Current) Summaries (AIMS)

Brief description

This data set contains summaries (daily, monthly, seasonal, annual) of the eReefs CSIRO hydrodynamic model outputs (GBR 4km v2.0 and GBR 1km v 2.0), covering water temperature, salinity and current at 6 depths (GBR1: 1.5m, 18m, 49m, 103m, 200m and 315m, GBR4: 2.35m, 18m, 49m, 103m, 200m and 315m). These summaries are aggregates derived from the original hourly model data made available via the National Computing Infrastructure (NCI). These summaries have been re-gridded from the original curvilinear grid used by the eReefs model into a regular grid so that the data files can be easily loaded into standard GIS software. These summaries are useful as they reduce the huge volume of the original model data down to a size that is manageable.

These aggregates data sets are updated in near-real time (daily) and are made available via a THREDDS server in NetCDF format. A subset of these outputs has been exported and converted to GeoTiff format for convenient download.

A subset of the the aggregate products are visualised on the AIMS eReefs Data Visualisation Portal (http://aims.ereefs.org.au).


Method:

The original source eReefs data is mirrored from the NCI THREDDS service then processed daily to update aggregate products. Aggregations are performed on the hourly data to create daily summaries. These are then used to create monthly, seasonal, annual aggregates.

As part of the process the data is re-gridded from the original curvilinear model grid to a regular grid using linear interpolation of the nearest four points up to a maximum distance of 4 times the grid spacing. For the GBR 4 model the outputs were re-gridded to 0.03 degrees (~3 km) and the GBR 1 model is regridded to 0.005 degrees (~500 m). The regular grids were chosen to be finer than the original grids to minimise defects introduced by the regridding process.


Data Dictionary:

The following summary variables are available:
- max_cur: Maximum sea water velocity (current) magnitude (ms-1)
- min_cur: Minimum sea water velocity (current) magnitude (ms-1)
- mean_cur: Mean sea water velocity (current) magnitude (ms-1)
- v: Northward sea water velocity (half of the current vector) (ms-1)
- u: Eastward sea water velocity (second half of the current vector) (ms-1)
- salt: Salinity (PSU)
- temp: Temperature (degrees C)
- max_wspeed: Maximum window speed magnitude
- min_wspeed: Minimum window speed magnitude
- wspeed_v: Northward wind (ms-1)
- wspeed_u: Eastward wind (ms-1)


Limitations:

The wind data is originally from the BOM Access-R weather models. These models capture synoptic winds and some of the features of cyclones, however they do not represent the high speed winds near the eye of cyclones well. For this reason the maximum wind speed aggregations do not capture the peak winds of cyclones.

The GBR1 yearly summaries of salinity and temperature have a known problem where the data is WRONG with a sharp boundary appearing at edge of the GBR. Do not use this data. We will investigate and resolve the issue with this data.


Product extracts:

GBR_AIMS-CSIRO_eReefs_GBR1-Hydro-v2_Mean-current_2015-2016_-2.35m.zip
This extract contains annual summaries of the surface mean current for 2015 and 2016 converted to GeoTiff format. This conversion was performed in ArcMap using the 'Make netcdf raster layer' tool to load the NetCDF file, then the data was exported as GeoTiff images.