Level 1 data (velocity profilers): Difference between revisions

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{{ReviewStage
{{ReviewStage
|toreview=Draft
|toreview=Ready for review
|authors=Cynthia
|authors=Cynthia
|instrument_type=Velocity profilers
|instrument_type=Velocity profilers
}}
}}
The required dimensions and variables for the first processing level within NetCDF ATOMIX format for ADCP velocity measurements are described below.  This processing level contains the raw measurements recorded by the instrument. If sampling is in burst mode, the measurements from individual bursts are appended together.  
The required dimensions and variables for the first processing level within NetCDF ATOMIX format for ADCP velocity measurements are described below.  This processing level contains the raw measurements recorded by the instrument. If sampling is in [[Burst sampling|burst mode]], the measurements from individual [[Burst sampling|bursts]] are appended together.  


Only a few attributes for each variable are listed since the page's purpose is to describe the information layout within each NetCDF file. {{FontColor|bg=#fca1fd|text=Please refer to the [[NetCDF_parameter|complete list]] for the additional attributes}} related to each variable.
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 {{FontColor|bg=#fca1fd|text= [[NetCDF_parameter|complete list]]}} for the additional attributes related to each variable (e.g., units, bounds, cell_methods).


=Dimensions=
=Dimensions=
Line 22: Line 22:
| time
| time
| TIME
| TIME
| Units in Days since 1950-01-01T00:00:00Z
| Units in Days since reference time specified in variable attribute
|-
|-
| R_DIST
| Z_DIST
| distance_from_sensor_along_beams
| distance_from_sensor_along_vertical
| R_DIST
| Z_DIST
| along-beam bin centre distance (in meters) from the transducer 
| bin centre distance (in meters) from the transducer along the instrument's vertical axis
|-
|-
| N_BEAM
| N_BEAM
| unique_identifier_for_each_beam
| unique_identifier_for_each_beam
| N_BEAM
| N_BEAM
| Array of 1 to number of beams (4 or 5 typically)  
| Array of 1 to number of beams (3 to 5 typically)  
|-
| colspan="4" style="text-align:center; font-weight:bold; background-color:#f9eddd"|  Optional dimensions
|-
| R_DIST5
| distance_from_sensor_along_beam_5
| R_DIST5
| along-beam bin centre distance (in meters) from the 5th beam, which is usually aligned with vertical axis of the ADCP. 
|}
|}
</div>
</div>
Line 54: Line 47:
! Comments and units
! Comments and units
|-
|-
| RVEL
| R_VEL
| radial_velocity_of_scatterers_toward_instrument_in_each_beam
| water_radial_velocity_of_scatterers_
| TIME, R_DIST, N_BEAM
towards_instrument. 
| Units in m/s  
| TIME, Z_DIST, N_BEAM
| Units in m/s. Corresponds to <math> b </math> in [[Nomenclature]]
|-
| R_VEL_FLAGS
| water_radial_velocity_of_scatterers_
towards_instrument_status_flag
| TIME, Z_DIST, N_BEAM
| Boolean flags (8 bit, 0-255) to represent one of 8 possible reasons for rejection. {{FontColor|fg=white|bg=red|text= Link to own flagging page}}
|-
|-
| THETA
| THETA
| beam_angle_from_instrument_z_axis
| beam_angle_from_instrument_z_axis
| TIME, N_BEAM
| N_BEAM
| Units in degrees, positive (usually ~20-30o)
| Units in degrees, positive (usually ~20-30<math>^\circ</math>)
|-
|-
| BIN_SIZE
| BIN_SIZE
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| vertical size of the ADCP bins. Usually the same for all 4 beams, but 5th beam can vary.
| vertical size of the ADCP bins. Usually the same for all 4 beams, but 5th beam can vary.
|-
|-
| BURST_NUMBER
| colspan="4" style="text-align:center; font-weight:bold; background-color:#f9eddd" | '''Quality-control variables recorded by acoustic-Doppler instruments''' <math>\ddagger</math>
| unique_identifier_for_each_burst
|-
| TIME
| ABSIC
| Integers of 1, 2, etc to designate which burst the velocities are associated with. Can set all to 1 if continuously sampled.
| backscatter_intensity
| TIME,  Z_DIST, N_BEAM
| Units of counts
|-
| CORR
| correlation_magnitude_from_each_acoustic_beam
| TIME, Z_DIST, N_BEAM
| Unit of counts
|-
|-
| colspan="4" style="text-align:center; font-weight:bold; background-color:#f9eddd" | '''Platform motion variables'''
| colspan="4" style="text-align:center; font-weight:bold; background-color:#f9eddd" | '''Platform motion variables''' <math>\dagger</math>
|-
|-
| HEADING
| HEADING
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| degrees
| degrees
|-
|-
| colspan="4" style="text-align:center; font-weight:bold; background-color:#f9eddd" | '''Quality-control variables recorded by acoustic-Doppler instruments''' <math>\ddagger</math>
| colspan="4" style="text-align:center; font-weight:bold; background-color:#f9eddd" | '''Optional variables''' <math>\dagger\dagger</math>
|-
|-
| ABSI
| BURST_NUMBER
| backscatter_intensity_from_each_acoustic_beam
| unique_identifier_for_each_burst
| TIME, R_DIST, N_BEAM
| TIME
| db
| Integers of 1, 2, etc to designate which [[Burst sampling|burst]] the velocities are associated with.  Only required when measuring in burst-mode.
|-
|-
| CORR
| PROFILE_NUMBER
| correlation_magnitude_from_each_acoustic_beam
| unique_identifier_for_each_profile
| TIME,  R_DIST, N_BEAM
| TIME
| {{FontColor|fg=red|text=can't remember}}
| This variable identifies each record (velocity) profile
|-
|-
| colspan="4" style="text-align:center; font-weight:bold; background-color:#f9eddd" | '''Optional variables for [[:File:SF atomix ADCP.png|5-beam ADCP]]'''<math>\dagger</math>
| colspan="4" | <math>\ddagger</math> Quality-control variable names are consistent for those onboard RDI Teleydyne ADCPs. Nortek has CORRN (noise correlation as a % instead of counts) detailed in the [[Level_1_data_(velocity_point-measurements)#Variables|ADV Level 1 variables]].
|-
 
| RVEL5
<math>\dagger</math> Motion variables are necessary for structure function analysis for situating the bins relative the vertical (gravity). These variables do enable converting measurements into geographical.
| radial_velocity_of_scatterers_toward_instrument_of_beam_5
| TIME, R_DIST5
| Units in m/s
|-
| colspan="4" | <math>\ddagger</math> Quality-control variable names are consistent for those onboard RDI Teleydyne ADCPs. {{FontColor|fg=white|bg=red|text= Not sure for Nortek, perhaps they use the same as their Vectors}} detailed in the [[Level_1_data_(velocity_point-measurements)#Variables|ADV Level 1 variables]].


<math>\dagger</math> 5-beam ADCPs has the 5th beam usually pointing directly up with its own bin sampling height, and may also be sampled at a different rate. In these situations, the data must be stored in separate variables given the different dimensions assigned. Simply append the number 5 to the variable name (e.g., TIME5)
<math>\dagger\dagger</math> BURST_NUMBER is only required when measuring in bursts e.g., 18 min of continuous measurements every hour. Can omit if continuously sampled. 
PROFILE_NUMBER is essentially an integer proxy for TIME.
|}
|}


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| PRES
| PRES
| sea_water_pressure
| sea_water_pressure
| TIME, N_VEL_INSTRUMENT
| TIME
| dbar, equals 0 at the sea surface and positive down.
| dbar, equals 0 at the sea surface and positive down.
|-
|-
| TEMP<math>\dagger</math>
| TEMP*
| sea_water_temperature
| sea_water_temperature
| TIME
| TIME
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</div>
</div>
=Group attributes (metadata)=
<div class="mw-collapsible"  id="raw_att" data-expandtext="Expand group attributes" data-collapsetext="Collapse attributes">
<br>
This section describes attributes that may provide additional information about how the data was processed and manipulated at this stage.
{| class="wikitable"
|-
! Attribute name
! Purpose
! Suggested content
|-
| processing_level
| Boilerplate about the ATOMIX Level 1 content.
| <blockquote>''This group includes the raw measurements from the recorder and ancillary measurements required for quality-controlling them using the manufacturer's recommendations.''</blockquote>
|-
| comment (optional)
| Information is pertinent to problems in the raw data files during collection.
| Examples: Stitching of files, corruption of binary files that were recovered by the manufacturer, etc.
|}
</div>


----
----
Return to [[Dataset requirements for ADCP structure function]]
Return to [[Dataset requirements for ADCP structure function]]


Go to [[Level 2 data (velocity profilers)| Level 2 quality-controlled and segmented velocities]]
Go to [[Level 2 data (velocity profilers)| Level 2 segmented]]

Latest revision as of 16:22, 24 May 2022

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

The required dimensions and variables for the first processing level within NetCDF ATOMIX format for ADCP velocity measurements are described below. This processing level contains the raw measurements recorded by the instrument. If sampling is in burst mode, the measurements from individual bursts are appended together. 

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 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)

Variables


Required variables

Short name Standard name Dimensions Comments and units
R_VEL water_radial_velocity_of_scatterers_

towards_instrument.

TIME, Z_DIST, N_BEAM Units in m/s. Corresponds to [math]\displaystyle{ b }[/math] in Nomenclature
R_VEL_FLAGS water_radial_velocity_of_scatterers_

towards_instrument_status_flag

TIME, Z_DIST, N_BEAM Boolean flags (8 bit, 0-255) to represent one of 8 possible reasons for rejection. Link to own flagging page
THETA beam_angle_from_instrument_z_axis N_BEAM Units in degrees, positive (usually ~20-30[math]\displaystyle{ ^\circ }[/math])
BIN_SIZE instrument_measurement_volume_bin_size N_BEAM vertical size of the ADCP bins. Usually the same for all 4 beams, but 5th beam can vary.
Quality-control variables recorded by acoustic-Doppler instruments [math]\displaystyle{ \ddagger }[/math]
ABSIC backscatter_intensity TIME, Z_DIST, N_BEAM Units of counts
CORR correlation_magnitude_from_each_acoustic_beam TIME, Z_DIST, N_BEAM Unit of counts
Platform motion variables [math]\displaystyle{ \dagger }[/math]
HEADING platform_yaw_angle TIME degrees, clockwise from true North
PITCH platform_pitch_angle TIME degrees
ROLL platform_roll_angle TIME degrees
Optional variables [math]\displaystyle{ \dagger\dagger }[/math]
BURST_NUMBER unique_identifier_for_each_burst TIME Integers of 1, 2, etc to designate which burst the velocities are associated with. Only required when measuring in burst-mode.
PROFILE_NUMBER unique_identifier_for_each_profile TIME This variable identifies each record (velocity) profile
[math]\displaystyle{ \ddagger }[/math] Quality-control variable names are consistent for those onboard RDI Teleydyne ADCPs. Nortek has CORRN (noise correlation as a % instead of counts) detailed in the ADV Level 1 variables.

[math]\displaystyle{ \dagger }[/math] Motion variables are necessary for structure function analysis for situating the bins relative the vertical (gravity). These variables do enable converting measurements into geographical.

[math]\displaystyle{ \dagger\dagger }[/math] BURST_NUMBER is only required when measuring in bursts e.g., 18 min of continuous measurements every hour. Can omit if continuously sampled. PROFILE_NUMBER is essentially an integer proxy for TIME.

Optional ancillary variables

Short name Standard name Dimensions Comments
PRES sea_water_pressure TIME dbar, equals 0 at the sea surface and positive down.
TEMP* sea_water_temperature TIME degrees_Celsius, in-situ temperature ITS-90 scale
*Data from concurrent sensors may be optionally included e.g., salinity, dissolved oxygen. Kinematic viscosity of seawater needs to be calculated during processing,

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 ATOMIX Level 1 content.

This group includes the raw measurements from the recorder and ancillary measurements required for quality-controlling them using the manufacturer's recommendations.

comment (optional) Information is pertinent to problems in the raw data files during collection. Examples: Stitching of files, corruption of binary files that were recovered by the manufacturer, etc.


Return to Dataset requirements for ADCP structure function

Go to Level 2 segmented

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