Level 3 data (velocity profilers)

Page status: Draft
Author(s):	Cynthia
Reviewer(s):
Comment:

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Schematic of ADCP processing nomenclature

The required dimensions and variables for the structure-function processing level within NetCDF ATOMIX format for velocity ADCP measurements are described below. This NetCDF group contains the structure function (DLL) calculated as a function of the along-beam separation for the available/usable ADCP bins.

Dimensions

Short name	Standard name	Dimensions	Comments
TIME	time	TIME	Units in Days since 1950-01-01T00:00:00Z
N_BEAM	unique_identifier_for_each_beam	N_BEAM	Array of 1 to number of beams (4 or 5 typically)
R_DIST	distance_from_sensor_along_beams	R_DIST	Along-beam bin centre distance (in meters) from the transducer
R_DEL??	??	R_DEL (variable?)
Optional dimensions for 5-beam ADCP <math>\ddagger</math>
R_DIST5	distance_from_sensor_along_beam_5	R_DIST5	Along-beam bin centre distance (in meters) from the transducer for the 5th vertical beam

Variables

Short name	Standard name	Dimensions	Comment
DLL	water_radial_velocity_of_scatterers_toward_instrument_in_each_beam	TIME, R_DIST, R_DEL, N_BEAM
N_SEGMENT	unique_identifier_for_each_ segment_in_the_entire_available_timeseries	TIME	Enables backtracking to previous processing level
BURST_NUMBER <math>\dagger\dagger</math>	unique_identifier_for_each_burst	TIME	Only required when measuring in burst-mode. Integers of 1, 2, etc to designate which burst the velocities are associated with.
Optional dimensions for 5-beam ADCP <math>\ddagger</math>
DLL5	water_radial_velocity_of_scatterers_toward_instrument_in_beam_5	TiME, R_DEL5, R_DIST5	Only necessary for 5-beam ADCP
<math>\dagger\dagger</math> Variable required only when measuring in bursts e.g., 18 min of continuous measurements every hour.

Group attributes (metadata)

This section describes attributes that may provide additional information about how the data was processed and manipulated at this stage.

Attribute name	Purpose	Suggested content
processing_level	Boilerplate about the content of the NetCDF group.	This group includes the structure function Dll as a function of the separation distance. Any ancillary information required for estimatng the dissipation of turbulent kinetic energy may also be stored here.
dll_calculation_type	Specify differencing technique used to estimate DLL	Examples include Central-differencing Forward-differencing
Optional group attributes <math>\ddagger</math>
stationarity_testing	Any testing done on the segment to verify stationarity?
noise_testing	Details of testing the noise levels, or if the signal comprises mostly of noise?
comment (optional)	Any additional information pertinent to other users who test their algorithms against the file.

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