For Nortek and RDI ADCP data file products (MAT and netCDF formats)
For Nortek and RDI ADCP daily current plot products (PNG and PDF formats)
Ensemble Period:
- Data not altered (none)
- 1 Minute
- 10 Minute
- 15 Minute
- 1 Hour
When selecting any of the ensemble periods, this option will cause the search to perform the standard box-car average resampling on the data. 'Boxes' of time are defined based on the ensemble period, e.g. starting every 15 minutes on the 15s, with the time stamp given as the center of the 'box'. Acoustic pings that occur within that box are averaged and the summary statistics are updated. This process is often called 'ping averaging'. The process uses log scale averaging on the intensity data, which involves backing out the logarithmic scale, compute the weighted average, and then compute the logarithmic scale again. Weighted averages are used when raw files bridge an ensemble period and when the data is already an ensemble or ping average.
New files are started when the maximum records per file is exceeded (usually set to make files that will use less than 1 GB of memory when loaded), or when there is a configuration, device or site changes. In the case where there is data from either side of a configuration change within the one ensemble period, two files will be produced with the same ensemble period, with the same time stamps, but different data. Users may use the ensemble statistics on the number of pings or samples per ensemble to filter out ensembles that do not have enough data. (As an aside, we do this by default with clean averaged scalar data - each ensemble period needs to have at least 70% of it's expected data to be reported as good.)
The default value is no averaging, meaning the data is not altered. This option is only available for MAT and NETCDF files.
File-name mode field
Selecting an ensemble period will add 'Ensemble' followed by the ensemble period. For example '-Ensemble600s'.
Velocity Bin-mapping
This option specifies the bin-mapping processing method to be applied. Bin-mapping is also known as 'depth cell mapping' or 'tilt compensation' or even 'map to vertical'. There are two methods, both correct for tilt effects on ADCP velocity data, while the none option leaves the velocity data as is. For details on the two methods, see the section on correction and rotation of velocities (included below). The 'None' option is the default for Nortek ADCPs since the free version of the manufacturer's software does not apply bin-mapping (a core goal of our data products is to replicate the functionality offered by the manufacturer's software). The 'Nearest vertical bin' is the default for RDI ADCPs as winADCP and onboard Earth rotations apply this method. The best method has been shown to be the linear interpolation method (Ott, 1992).
File-name mode field
The velocity bin-mapping option will be appended to the filename. For example: '-binMapNone', 'binMapLinearInterp', 'binMapNearest'.
Horizontal / Vertical Current Plot Limits
This option allows the user to select automatic or fixed limits for ADCP daily current plots. The limits are on the colour axis of the daily current plots for either horizontal currents (East u, North v) or vertical currents (Up w) and are symmetric about zero (to support the diverging colour map, maintaining zero as white). The fixed limits have the benefit of being consistent from plot to plot, while the automatic limits can very. The automatic limit does attempt to maintain stable, suitable limits; the limit is selected from the same set of fixed limits that is available to the user by finding the limit that is greater than or equal the 90th percentile of one-side horizontal or vertical current data.
File-name mode field
Selecting a limit option other than 'Automatic' will append to the file-name a '-Limit', following by the two limits selected, without the decimal point or trailing zeros. If one of the limits is automatic, 'Auto' will appear. Examples: '-Limit0105', '-Limit021', '-Limit05Auto', '-LimitAuto5'.