Level 3 data (velocity profilers): Difference between revisions

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Updated dimension to be N_DEL instead of R_DEL
Change dll_calculation type to dll_method for consistency with Brian's data
 
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| time
| time
| TIME
| TIME
| Units in Days since 1950-01-01T00:00:00Z. Provide bounds attribute to designate the variable containing the limits of each segment ([http://cfconventions.org/cf-conventions/v1.6.0/cf-conventions.html#methods-applied-to-a-timeseries-ex see CF-compliant example]).
| Segment midpoint time. Units in Days since reference time specified in variable attribute.
|-
|-
| Z_DIST
| Z_DIST
| distance_from_sensor_along_z_instrument_axis
| distance_from_sensor_along_vertical
| Z_DIST
| Z_DIST
| bin centre distance (in meters) from the transducer along the instrument's vertical axis
| bin centre distance (in meters) from the transducer along the instrument's vertical axis
|-
| N_DEL
| along-beam_separation_distance_
over_which_DLL_is_evaluated_in_number_of_bins
| N_DEL
| Number of bins separating two velocity measurements used to calculate DLL
|-
|-
| N_BEAM
| N_BEAM
Line 39: Line 33:
| N_BEAM
| N_BEAM
| Array of 1 to number of beams (3 to 5 typically)
| Array of 1 to number of beams (3 to 5 typically)
|-
| N_DEL
| along-beam_separation_distance_over_
which_DLL_is_evaluated_in_number_of_bins
| N_DEL
| Number of bins separating two velocity measurements used to calculate DLL
|}
|}
</div>
</div>
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| DLL
| DLL
| second_order_structure_function
| second_order_structure_function
| TIME, Z_DIST, N_DEL, N_BEAM
| TIME, Z_DIST, N_BEAM, N_DEL
| Differences in velocities squared have been time-averaged (units of m2/s2).
| Differences in velocities squared have been time-averaged (units of m2/s2).
|-
|-
| DLL_FLAGS
| DLL_FLAGS
| second_order_structure_function_status_flags
| second_order_structure_function_
| TIME, Z_DIST, N_DEL, N_BEAM
status_flag
| {{FontColor|fg=white|bg=red|text=To be linked, when boolean flags defined}}
| TIME, Z_DIST, N_BEAM, N_DEL
| For details see [[Velocity Profiler data flags| Velocity profiler data flags]]
|-
|-
| R_DEL
| R_DEL
| along-beam_separation_distance_
| along-beam_separation_distance_at_
at_which_structure_function_is_evaluated
which_structure_function_is_evaluated
| N_DEL, Z_DIST, N_BEAM, TIME
| N_BEAM, N_DEL
| Estimated quantity (in meters) from bin sizes and theta in Level 2 qaqc variables
| Estimated quantity (in meters) from N_DEL (Level 3), BIN_SIZE (Level 2) and THETA (Level 2).
|-
|-
| R_DIST
| R_DIST
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|-
|-
| DLL_N
| DLL_N
| second_order_structure_function_number_of_observations
| second_order_structure_function_number_
| TIME, Z_DIST, N_DEL, N_BEAM
of_observations
| Measure the number of available measurements in each segment i.e., data quality.
| TIME, Z_DIST, N_BEAM, N_DEL
| The number of available measurements in each segment i.e., data quality.
|-
|-
| N_SEGMENT
| N_SEGMENT
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| TIME
| TIME
| Enables backtracking to [[Level 2 segmented (velocity profilers)|previous processing level]]
| Enables backtracking to [[Level 2 segmented (velocity profilers)|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.
|-
| colspan="4" |
<math>\dagger\dagger</math> Optional variable required only when measuring in bursts e.g., 18 min of continuous measurements every hour.
|}  
|}  
</div>
</div>
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| <blockquote>''This group includes the structure function Dll as a function of the separation distance.  Any ancillary information required for estimating the dissipation of turbulent kinetic energy may also be stored here. ''</blockquote>
| <blockquote>''This group includes the structure function Dll as a function of the separation distance.  Any ancillary information required for estimating the dissipation of turbulent kinetic energy may also be stored here. ''</blockquote>
|-
|-
| dll_calculation_type
| dll_method
| Specify differencing technique used to estimate DLL
| Specify differencing technique used to estimate DLL
| Examples include:
| Examples include:

Latest revision as of 13:53, 8 July 2022

Page status: Ready for review
Author(s): Cynthia
Reviewer(s):
Comment:
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. 

Only a few attributes for each variable are listed since the page's purpose is to describe the information layout within each NetCDF file. Please refer to the complete list for the additional attributes related to each variable (e.g., units, bounds, cell_methods).

Dimensions

Short name Standard name Dimensions Comments
TIME time TIME Segment midpoint time. Units in Days since reference time specified in variable attribute.
Z_DIST distance_from_sensor_along_vertical Z_DIST bin centre distance (in meters) from the transducer along the instrument's vertical axis
N_BEAM unique_identifier_for_each_beam N_BEAM Array of 1 to number of beams (3 to 5 typically)
N_DEL along-beam_separation_distance_over_

which_DLL_is_evaluated_in_number_of_bins

N_DEL Number of bins separating two velocity measurements used to calculate DLL

Variables


Short name Standard name Dimensions Comment
DLL second_order_structure_function TIME, Z_DIST, N_BEAM, N_DEL Differences in velocities squared have been time-averaged (units of m2/s2).
DLL_FLAGS second_order_structure_function_

status_flag

TIME, Z_DIST, N_BEAM, N_DEL For details see Velocity profiler data flags
R_DEL along-beam_separation_distance_at_

which_structure_function_is_evaluated

N_BEAM, N_DEL Estimated quantity (in meters) from N_DEL (Level 3), BIN_SIZE (Level 2) and THETA (Level 2).
R_DIST distance_from_sensor_along_beams Z_DIST, N_BEAM Along-beam bin centre distance (in meters) from the transducer
DLL_N second_order_structure_function_number_

of_observations

TIME, Z_DIST, N_BEAM, N_DEL The number of available measurements in each segment i.e., data quality.
N_SEGMENT unique_identifier_for_each_segment_

in_the_entire_available_timeseries

TIME Enables backtracking to previous processing level

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 estimating the dissipation of turbulent kinetic energy may also be stored here.

dll_method Specify differencing technique used to estimate DLL Examples include:

Central-differencing

Forward-differencing

Optional group attributes [math]\displaystyle{ \ddagger }[/math]
stationarity_testing Any testing done on the segment to verify stationarity? To be revisited once testing begins. Tentatively refer to demo yaml file.
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.

Return to Level 2 segmented velocities

Go to Level 4 dissipation estimates

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