Dataset requirements for shear probes: Difference between revisions

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== The absolute minimum data set ==


The absolute minimum signals and information required to estimate the rate of dissipation of kinetic energy consists of:
This page provides an overview of the NetCDF format of benchmark dataset for instruments that measure microstructure shear using airfoil probes. The data format recommended is summarized in [[#Shear probe measurements: Data Format|Data Format]] below.
<br>
Please use the following naming convention for  [[Netcdf dimensions (shear probes)|standard dimensions]] and include the necessary [[Netcdf meta data (shear probes)|meta data]].


* a sampled shear-probe signal, 
* [[Netcdf meta data (shear probes)|list of meta data]]
* a means of determining the speed of flow past the shear probe, and 
* [[Netcdf dimensions (shear probes)|list of dimension names]]
* a means to estimate the temperature of the fluid so that you can determine its kinematic viscosity. 
* [[Quality_control_coding|quality control coding for dissipation estimates]]


The sampling rate of the shear-probe signal should exceed significantly (by a factor of 2 to 4) the value of 150U, where
ATOMIX provides several [[Tentative benchmarks for shear probes|benchmark data sets]] following these guidelines.
U is the speed of the flow past the shear-probe. This speed is often called the speed of profiling, even when the probe is fixed in space and the current causes fluid to flow past the shear probe. The value of 150 cpm equals the spatial resolution of the commonly used shear probe.
 
== The desirable data set  ==


= Minimum and desirable data set =
<div class="mw-collapsible" id="dataset" data-collapsetext="Collapse" data-expandtext="Expand">


A far more desirable, but not absolutely necessary, set of data consists of the following.


* Two or more shear probes for measurement redundancy. 
* The absolute minimum signals and information required to estimate the rate of dissipation of kinetic energy consists of:
* Vibration sensors or accelerometers that are sensitive to the directions of sensitivity of the shear probes. 
* An accurate thermometer. 
* A pressure transducer. 
* A signal that can be used to estimate the speed of flow past the shear probe. 
* Pitch and roll sensors.


Most commonly available instruments carry two shear probes that are frequently oriented so that they measure orthogonal components of the shear and, thus, provide two independent estimates of the rate of dissipation that you should agree statistically.
:* a sampled shear-probe signal, 
:* a means of determining the speed of flow past the shear probe, and
:* a means to estimate the temperature of the fluid so that you can determine its kinematic viscosity.


== Recommended data format ==
In addition, it is highly recommended to have a minimum one vibration sensor or accelerometer that can be used to check and eventually correct for platform vibrations. The sampling rate of the shear-probe signal should exceed significantly (by a factor of 2 to 4) the value of 150U, where
<div class="mw-collapsible mw-collapsed" id="Recommended" data-collapsetext="Collapse" data-expandtext="data format">
U is the speed of the flow past the shear-probe. This speed is often called the speed of profiling, even when the probe is fixed in space and the current causes fluid to flow past the shear probe. The value of 150 cpm equals the spatial resolution of the commonly used shear probe.


For sharing a data set, we recommend to provide four processing levels of data in a single netCDF file per instrument file. The processing levels include
* L1_converted ([[Level 1 data (shear probes)|level 1]])
* L2_cleaned ([[Level 2 data (shear probes)|level 2]])
* L3_spectra ([[Level 3 data (shear probes)|level 3]])
* L4_dissipation ([[Level 4 data (shear probes)|level 4]])
* Ancillary
   
   
The data format recommended is summarized in [[Netcdf dimensions (shear probes)|standard dimensions]] and should include necessary [[Netcdf meta data (shear probes)|meta data]]. ATOMIX provides several [[Benchmark datasets for shear probes|benchmark data sets]] following these guidelines.
* The desirable data set


__TOC__
A far more desirable, but not absolutely necessary, set of data consists of the following.


This section provides an overview of the NetCDF format of benchmark dataset for instruments that measure microstructure shear.
:* Two or more shear probes for measurement redundancy. 
:* Vibration sensors or accelerometers that are sensitive to the directions of sensitivity of the shear probes. 
:* An accurate thermometer. 
:* A pressure transducer. 
:* A signal that can be used to estimate the speed of flow past the shear probe. 
:* Pitch and roll sensors.  


= Raw timeseries =
Most commonly available instruments carry two shear probes that are frequently oriented so that they measure orthogonal components of the shear and, thus, provide two independent estimates of the rate of dissipation that you should agree statistically.
<div class="mw-collapsible mw-collapsed" id="raw" data-collapsetext="Collapse" data-expandtext="Expand Raw">
 
[[User:CynthiaBluteau|CynthiaBluteau]] ([[User talk:CynthiaBluteau|talk]]) 19:44, 28 October 2021 (CEST) COuld be collapsible tables or simply bullet lists. Instead of each sublevel into subheadings, they can be in their separate pages.
==Dimensions==
'''Example of collapsible list'''
<ul class="mw-collapsible">
  <li>TIME</li>
  <li>HEIGHT_AS</li>
</ul>
 
 
'''Example of collapsible table'''
{| class="wikitable sortable mw-collapsible"
! Short name
! Standard name
|-
| TIME
| ...
|-
| HEIGHT_AS
| nominal_height_above_seabed
|}
 
 
{| class="wikitable sortable mw-collapsible"
|+ These dimensions are defined for the raw group level but have a caption.
! Short name
! Standard name
|-
| Content
| Goes
|-
| In Here
| Please
|}
 
==Variables==
{| class="wikitable sortable mw-collapsible"
|+ These variables are defined at group level
! Short name
! Long (standard) name
! Dimensions
|-
| Content
| Goes
| In
|-
| Here
| Please
|
|}
 
==Group Attributes (metadata)==
<div class="mw-collapsible"  id="raw_att"  data-expandtext="Expand Raw Attributes" data-collapsetext="Collapse attributes">
===Required===
<ul>
  <li>Att 1</li>
  <li>Att2</li>
</ul>
 
===Optional ===
<ul>
<li>Enter here</li>
</ul>
</div>
</div>


</div>


=Quality-controlled and segmented timeseries=
= Shear probe measurements: Data Format =
<div class="mw-collapsible mw-collapsed" id="segmented" data-collapsetext="Collapse" data-expandtext="Expand QAQC timeseries">


Insert info here in the same format as [[#raw|Raw]]
Following the recommendations of the [[Flow chart for shear probes | flow chart]], ATOMIX defined four processing levels a user needs to follow to obtain a standardized estimation of epsilon. The different levels are stored as groups in the NetCDF file, the group names are in brackets:
</div>


=Spectra=
# [[Level 1 data (shear probes)|Timeseries in physical units (L1_converted)]]
<div class="mw-collapsible mw-collapsed" id="spectra" data-collapsetext="Collapse" data-expandtext="Expand Spectra">
#* full resolution data in physical units
# [[Level 2 data (shear probes)|Quality-controlled and segmented timeseries (L2_cleaned)]]
#* full resolution cleaned and despiked parameters from level 1, subdivided in individual [[Section|sections]].
# [[Level 3 data (shear probes)|Spectra (L3_spectra)]]
#* raw and cleaned spectra
# [[Level 4 data (shear probes)|Dissipation <math>\varepsilon</math> estimates (L4_dissipation)]]
#* dissipation estimates and corresponding quality parameter as time series


</div>
-------------------
return to [[Shear probes]]


=Dissipation=
<div class="mw-collapsible mw-collapsed" id="dissipation" data-collapsetext="Collapse" data-expandtext="Expand Dissipation">


</div>
[[Category:Shear probes]]

Latest revision as of 15:59, 9 September 2023

This page provides an overview of the NetCDF format of benchmark dataset for instruments that measure microstructure shear using airfoil probes. The data format recommended is summarized in Data Format below.
Please use the following naming convention for standard dimensions and include the necessary meta data.

ATOMIX provides several benchmark data sets following these guidelines.

Minimum and desirable data set


  • The absolute minimum signals and information required to estimate the rate of dissipation of kinetic energy consists of:
  • a sampled shear-probe signal,
  • a means of determining the speed of flow past the shear probe, and
  • a means to estimate the temperature of the fluid so that you can determine its kinematic viscosity.

In addition, it is highly recommended to have a minimum one vibration sensor or accelerometer that can be used to check and eventually correct for platform vibrations. The sampling rate of the shear-probe signal should exceed significantly (by a factor of 2 to 4) the value of 150U, where U is the speed of the flow past the shear-probe. This speed is often called the speed of profiling, even when the probe is fixed in space and the current causes fluid to flow past the shear probe. The value of 150 cpm equals the spatial resolution of the commonly used shear probe.


  • The desirable data set

A far more desirable, but not absolutely necessary, set of data consists of the following.

  • Two or more shear probes for measurement redundancy.
  • Vibration sensors or accelerometers that are sensitive to the directions of sensitivity of the shear probes.
  • An accurate thermometer.
  • A pressure transducer.
  • A signal that can be used to estimate the speed of flow past the shear probe.
  • Pitch and roll sensors.

Most commonly available instruments carry two shear probes that are frequently oriented so that they measure orthogonal components of the shear and, thus, provide two independent estimates of the rate of dissipation that you should agree statistically.


Shear probe measurements: Data Format

Following the recommendations of the flow chart, ATOMIX defined four processing levels a user needs to follow to obtain a standardized estimation of epsilon. The different levels are stored as groups in the NetCDF file, the group names are in brackets:

  1. Timeseries in physical units (L1_converted)
    • full resolution data in physical units
  2. Quality-controlled and segmented timeseries (L2_cleaned)
    • full resolution cleaned and despiked parameters from level 1, subdivided in individual sections.
  3. Spectra (L3_spectra)
    • raw and cleaned spectra
  4. Dissipation [math]\displaystyle{ \varepsilon }[/math] estimates (L4_dissipation)
    • dissipation estimates and corresponding quality parameter as time series

return to Shear probes

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