Level 1 data (shear probes): Difference between revisions

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| TIME
| TIME
| Days since 1950-01-01 00:00:00 UTC  
| Days since 1950-01-01 00:00:00 UTC  
| microstructure sampling rate
| Time axis for the microstructure sampling rate
|-
|-
| TIME_CTD
| TIME_CTD
| Days since 1950-01-01 00:00:00 UTC  
| Days since 1950-01-01 00:00:00 UTC  
| CTD sampling rate.
| Time axis for the CTD sampling rate.
|-
|-
| TIME_VIB
| TIME_***
| Days since 1950-01-01 00:00:00 UTC  
| Days since 1950-01-01 00:00:00 UTC  
| Vibration sensor sampling rate  
| Time axis for the *** sensor sampling rate  
|-
| TIME_ACCEL
| Days since 1950-01-01 00:00:00 UTC
| Accelerometer sampling rate.
|-
| TIME_???
| Days since 1950-01-01 00:00:00 UTC
| Sampling rate different than microstructure sampling rate.
|-
|-
|N_SHEAR_SENSORS
|N_SHEAR_SENSORS
Line 71: Line 63:
|
|
|-
|-
|N_???_SENSORS
|N_***_SENSORS
|number of ??? channel
|number of *** channel
|
|
|-
|-
Line 85: Line 77:
| TIME || time || days since 1950-01-01 00:00:00 UTC || TIME || 1
| TIME || time || days since 1950-01-01 00:00:00 UTC || TIME || 1
|-
|-
| SHEAR || water_velocity_shear || s-1 || [TIME, n_shear_sensors] || 1
| SHEAR || water_velocity_shear || s-1 || [TIME, N_SHEAR_SENSORS] || 1
|}
|}


Line 99: Line 91:
| TEMP || sea_water_temperature<br /> (water_temperature) || degree_Celsius || [TIME_CTD,N_T_SENSORS  
| TEMP || sea_water_temperature<br /> (water_temperature) || degree_Celsius || [TIME_CTD,N_T_SENSORS  
|-
|-
| CNCD || sea_water_electrical_conductivity<br /> (water_electrical_conductivity) || S m-1 || [TIME_CNCD,N_C_SENSORS]  
| CNCD || sea_water_electrical_conductivity<br /> (water_electrical_conductivity) || S m-1 || [TIME_CTD,N_C_SENSORS]  
|-
|-
| GRADT || temperature_gradient ||  || [TIME_GRADT, N_GRADT_SENSORS]  
| GRADT || temperature_gradient ||  || [TIME_GRADT, N_GRADT_SENSORS]  

Revision as of 04:34, 9 November 2021

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.

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.

Level 1 data (shear probes)

TO DO: Fit the parameter names and definitions to the NetCDF parameter attributes


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.


Dimensions

Example of collapsible table

Short name Standard name description
TIME Days since 1950-01-01 00:00:00 UTC Time axis for the microstructure sampling rate
TIME_CTD Days since 1950-01-01 00:00:00 UTC Time axis for the CTD sampling rate.
TIME_*** Days since 1950-01-01 00:00:00 UTC Time axis for the *** sensor sampling rate
N_SHEAR_SENSORS number of shear channel
N_***_SENSORS number of *** channel


Required Variables

Parameter Name Standard Name Units of measurement dimension
TIME time days since 1950-01-01 00:00:00 UTC TIME 1
SHEAR water_velocity_shear s-1 [TIME, N_SHEAR_SENSORS] 1

Optional Level 1 Variables

Parameter Name Standard Name Units of measurement dimension
VIB platform_vibration NA [TIME_VIB, N_VIB_SENSORS]
ACC platform_acceleration m s-2 [TIME_ACCEL, N_ACC_SENSORS]
TEMP sea_water_temperature
(water_temperature)		 degree_Celsius [TIME_CTD,N_T_SENSORS
CNCD sea_water_electrical_conductivity
(water_electrical_conductivity)		 S m-1 [TIME_CTD,N_C_SENSORS]
GRADT temperature_gradient [TIME_GRADT, N_GRADT_SENSORS]
GRADC conductivity_gradient [TIME_GRADC, N_GRADC_SENSORS]
PITCH platform_pitch_angle degree [TIME_PITCH]
ROLL platform_roll_angle degree [TIME_ROLL]


return to Dataset requirements for shear probes.

Numbers in the last column indicate:

required=1 are the absolute minimum parameter required for a data set
required=2 are preferred/recommended parameter
required=3 are optional parameter
Parameter Name CF parameter Standard Name Units of measurement dimension required
TIME 1 time days since 1950-01-01 00:00:00 UTC TIME 1
SHEAR 0 water_velocity_shear s-1 [TIME, N_SHEAR_SENSORS] 1
PRES 1
0		 sea_water_pressure
water_pressure		 dbar TIME_CTD 1,2
VIB 0 platform_vibration NA [TIME_VIB, N_VIB_SENSORS] 2
ACC 0 platform_acceleration m s-2 [TIME_ACCEL, n_acc_sensors] 2
TEMP 1
(0)		 sea_water_temperature
(water_temperature)		 degree_Celsius [TIME_CTD,n_T_sensors] 2
CNCD 1
(0)		 sea_water_electrical_conductivity
(water_electrical_conductivity)		 S m-1 [TIME_CNCD,n_C_sensors] 2
GRADT temperature_gradient [TIME_GRADT, n_gradT_sensors] 3
GRADC conductivity_gradient [TIME_GRADC, n_gradC_sensors] 3
PITCH 1 platform_pitch_angle degree [TIME_PITCH] 2
ROLL 1 platform_roll_angle degree [TIME_ROLL] 2
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