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== Minimum and desirable data set ==
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* The absolute minimum signals and information required to estimate the rate of dissipation of kinetic energy consists of:
Level 1 data refers to the full resolution data in physical units, e.g. the regularly sampled time series of [[Convert the shear probe data|converted shear probe data]]. If needed, a transfer function for shear is given. Below, a table with parameters included in the level 1 data set is compiled. The data are stored as a NetCDF group with the name "L1_converted".
 
:* 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. 
 
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.
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== Level 1 data (shear probes) ==
 
Level 1 data refers to the full resolution data in physical units, e.g. the regularly sampled time series of [[Convert the shear probe data|converted shear probe data]]. If needed, a transfer function for shear is given. Below, a table with parameters included in the level 1 data set is compiled. The parameter names and definitions fit the [[NetCDF parameter]] attributes.


In the standard names, "sea_water" can be replaced with "water" if working in freshwater environments. This is specified in some entries below but not all.
In the standard names, "sea_water" can be replaced with "water" if working in freshwater environments. This is specified in some entries below but not all.




 
=Dimensions=
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<br>
'''Dimensions'''


{| class="wikitable sortable"
{| class="wikitable sortable"
! Dimension short name
! Dimension !! Description
! description
|-
|-
| TIME
| TIME || length of the record from turbulence (fast) data channels
| Time axis for the microstructure sampling rate
|-
|-
| TIME_CTD
| TIME_*** <math>^a</math> || length of the record from slow data channels (if different from fast)
| Time axis for the CTD sampling rate.
|-
|-
| TIME_*** <math>^a</math>
|N_SHEAR_SENSORS ||number of shear channels (shear sensors)
| Time axis for the *** sensor sampling rate
|-
|-
|N_SHEAR_SENSORS
|N_***_SENSORS <math>^b</math>  ||number of *** channel (sensors)
|number of shear channel
|-
|N_***_SENSORS
|number of *** channel (e.g., N_VIB_SENSORS, N_ACC_SENSORS)
|-
|-
|}
|}
<math>^a</math> Typically we assume TIME for the fast-sampled microstructure channels, and eventually _SLOW or _CTD for slower sampled channels such as CTD and tilt sensors. If the application requires different time stamps for different sensors, this can be utilized like TIME_PITCH, TIME_ACC etc.
<math>^a</math> Typically TIME is assumed for the fast-sampled microstructure channels. Use, e.g., TIME_SLOW or TIME_CTD for slower sampled channels such as CTD and tilt sensors. If the application requires different time stamps for different sensors, this can be utilized like TIME_PITCH, TIME_ACC etc.
<br>
<math>^b</math> Please use these examples for related sensors:<br>
N_VIB_SENSORS for vibration (piezo-acceleration) sensors, <br>
N_ACC_SENSORS for vibration acceleration sensors, <br>
N_GRADT_SENSORS for thermistors, <br>
N_GRADC_SENSORS for microconductivity sensors. <br>
</div>
 
=Variables=
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<br>


'''Required Variables'''
{| class="wikitable sortable"
{| class="wikitable sortable"
|-
|-
! Parameter Name !! Standard Name !! Units of measurement !! dimension
! Variable Name !! Req.<math>^a</math> !! Standard Name !! Unit !! Dimensions
|-
|-
| TIME || time || Days since YYYY-MM-DDT00:00:00Z || TIME  
| TIME || R || time || [http://cfconventions.org/cf-conventions/cf-conventions CF-Convention]<math>^b</math> || TIME  
|-
|-
| SHEAR || sea_water_velocity_shear<br /> (or water_velocity_shear)  || s-1 || [TIME, N_SHEAR_SENSORS]
| SHEAR || R || [sea]<math>^c</math>_water_velocity_shear || s-1 || TIME, N_SHEAR_SENSORS
|}
 
'''Optional Level 1 Variables'''
{| class="wikitable sortable"
|-
|-
! Parameter Name !! Standard Name !! Units of measurement !! dimension
| PSPD_REL || HR||  platform_speed_wrt_[sea]<math>^c</math>_water || m s-1 || TIME
|-
|-
| PSPD_REL || platform_speed_wrt_sea_water || m s-1 || TIME<math>^a</math>
| VIB || HR || platform_vibration || - || TIME, N_VIB_SENSORS
|-
|-
| VIB || platform_vibration || NA || [TIME, N_VIB_SENSORS]
| PRES || HR || [sea]<math>^c</math>_water_pressure|| dbar || TIME
|-
|-
| ACC || platform_acceleration || m s-2 || [TIME <math>^b</math>, N_ACC_SENSORS]
| TEMP || HR || [sea]<math>^c</math>_water_temperature || degree_Celsius || TIME, N_T_SENSORS
|-
|-
| TEMP || sea_water_temperature<br /> (water_temperature) || degree_Celsius || [TIME_CTD <math>^b</math>, N_T_SENSORS]
| ACC || O || platform_acceleration || m s-2 || TIME, N_ACC_SENSORS
|-
|-
| CNCD || sea_water_electrical_conductivity<br /> (water_electrical_conductivity) || S m-1 || [TIME_CTD <math>^b</math>, N_C_SENSORS]
| CNDC || O || [sea]<math>^c</math>_water_electrical_conductivity || S m-1 || TIME_CTD, N_C_SENSORS
|-
|-
| GRADT || temperature_gradient ||  || [TIME, N_GRADT_SENSORS]
| GRADT || O || derivative_of_[sea]<math>^c</math>_water_temperature_wrt_<math>^{*d}</math>||  degree_Celcius m-1 || TIME, N_GRADT_SENSORS  
|-
|-
| GRADC || conductivity_gradient || || [TIME, N_GRADC_SENSORS]
| GRADC || O || derivative_of_[sea]<math>^c</math>_water_conductivity_wrt_<math>^{*d}</math> || - || TIME, N_GRADC_SENSORS
|-
|-
| PITCH || platform_pitch_angle || degree || TIME <math>^a</math>
| PITCH || O || platform_pitch_angle || degree || TIME
|-
|-
| ROLL || platform_roll_angle || degree || TIME <math>^a</math>
| ROLL || O || platform_roll_angle || degree || TIME
|}
|}
 
<math>^a</math>: Code for the requirement of variable, R: Required, HR: Highly recommended, O: Optional
<br><math>^b</math>: Unit and offset need to be compatible with the Climate and Forecast (CF)-convention
<br><math>^c</math>: User can choose between water or sea_water depending on the environment
<br><math>^d</math>: wrt_x or wrt_s; spatial derivative. Typically derived from the rate of change of temperature and divided by the profiling speed.
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</div>
<math>^a</math> or TIME_SLOW or TIME_CTD
<math>^b</math> or TIME_SLOW




------
------
return to [[Dataset requirements for shear probes]].
return to [[Dataset requirements for shear probes]]  <br>
go to next: [[Level 2 data (shear probes)| Level 2 data]].




[[Category: Shear probes]]
[[Category: Shear probes]]

Latest revision as of 15:13, 6 June 2024


Level 1 data refers to the full resolution data in physical units, e.g. the regularly sampled time series of converted shear probe data. If needed, a transfer function for shear is given. Below, a table with parameters included in the level 1 data set is compiled. The data are stored as a NetCDF group with the name "L1_converted".

In the standard names, "sea_water" can be replaced with "water" if working in freshwater environments. This is specified in some entries below but not all.


Dimensions


Dimension Description
TIME length of the record from turbulence (fast) data channels
TIME_*** [math]\displaystyle{ ^a }[/math] length of the record from slow data channels (if different from fast)
N_SHEAR_SENSORS number of shear channels (shear sensors)
N_***_SENSORS [math]\displaystyle{ ^b }[/math] number of *** channel (sensors)

[math]\displaystyle{ ^a }[/math] Typically TIME is assumed for the fast-sampled microstructure channels. Use, e.g., TIME_SLOW or TIME_CTD for slower sampled channels such as CTD and tilt sensors. If the application requires different time stamps for different sensors, this can be utilized like TIME_PITCH, TIME_ACC etc.
[math]\displaystyle{ ^b }[/math] Please use these examples for related sensors:
N_VIB_SENSORS for vibration (piezo-acceleration) sensors,
N_ACC_SENSORS for vibration acceleration sensors,
N_GRADT_SENSORS for thermistors,
N_GRADC_SENSORS for microconductivity sensors.

Variables


Variable Name Req.[math]\displaystyle{ ^a }[/math] Standard Name Unit Dimensions
TIME R time CF-Convention[math]\displaystyle{ ^b }[/math] TIME
SHEAR R [sea][math]\displaystyle{ ^c }[/math]_water_velocity_shear s-1 TIME, N_SHEAR_SENSORS
PSPD_REL HR platform_speed_wrt_[sea][math]\displaystyle{ ^c }[/math]_water m s-1 TIME
VIB HR platform_vibration - TIME, N_VIB_SENSORS
PRES HR [sea][math]\displaystyle{ ^c }[/math]_water_pressure dbar TIME
TEMP HR [sea][math]\displaystyle{ ^c }[/math]_water_temperature degree_Celsius TIME, N_T_SENSORS
ACC O platform_acceleration m s-2 TIME, N_ACC_SENSORS
CNDC O [sea][math]\displaystyle{ ^c }[/math]_water_electrical_conductivity S m-1 TIME_CTD, N_C_SENSORS
GRADT O derivative_of_[sea][math]\displaystyle{ ^c }[/math]_water_temperature_wrt_[math]\displaystyle{ ^{*d} }[/math] degree_Celcius m-1 TIME, N_GRADT_SENSORS
GRADC O derivative_of_[sea][math]\displaystyle{ ^c }[/math]_water_conductivity_wrt_[math]\displaystyle{ ^{*d} }[/math] - TIME, N_GRADC_SENSORS
PITCH O platform_pitch_angle degree TIME
ROLL O platform_roll_angle degree TIME

[math]\displaystyle{ ^a }[/math]: Code for the requirement of variable, R: Required, HR: Highly recommended, O: Optional
[math]\displaystyle{ ^b }[/math]: Unit and offset need to be compatible with the Climate and Forecast (CF)-convention
[math]\displaystyle{ ^c }[/math]: User can choose between water or sea_water depending on the environment
[math]\displaystyle{ ^d }[/math]: wrt_x or wrt_s; spatial derivative. Typically derived from the rate of change of temperature and divided by the profiling speed.


return to Dataset requirements for shear probes
go to next: Level 2 data.

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