Level 3 data (shear probes): Difference between revisions

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== Level 3 data (shear probes) ==


Level 3 data contains the raw and cleaned [[Spectrum|spectra]] derived from level 2 data. Level 3 parameter are defined along a new time [[Netcdf dimensions (shear probe)|dimension]], TIME_SPECTRA, which is the average time of the individual spectral segments. The length of the TIME_SPECTRA dimension equals the number of spectral segments. Parameter for the calculation of the spectra, e.g. segment length, are provided in the [[Netcdf meta data (shear probes)|meta data]]. Repeated level 1 and 2 parameter are provided as average over the segment length.
Level 3 data contains the raw (and optionally cleaned) [[Spectrum|spectra]] derived from level 2 time series and is saved in the NetCDF group "L3_spectra". Level 3 parameters are defined along a new TIME [[Netcdf dimensions (shear probes)|dimension]], which is the average time of the individual spectral segments. The length of the TIME dimension equals the number of spectral segments. Parameter for the calculation of the spectra, e.g. segment length, are provided in the [[Netcdf meta data (shear probes)|meta data]].


{| class="wikitable"
 
 
=Dimensions=
<div class="mw-collapsible mw-expand" data-collapsetext="Collapse" data-expandtext="Expand">
<br>
 
{| class="wikitable sortable"
! Dimension name !! description
|-
| TIME_SPECTRA || length of the record of average times of spectral segments
|-
| N_WAVENUMBER || length of the wavenumber array
|-
| N_SHEAR_SENSORS || number of shear channels (shear sensors)
|-
| N_***_SENSORS || number of *** channels
|-
| N_SH_ACC_SPEC || number of shear-acceleration cross spectra
|-
| N_SH_VIB_SPEC || number of shear-vibration cross spectra
|-
|-
! Parameter Name !! CF parameter !! Standard Name !! Units of measurement !! dimension !! Comment
| N_GLOBAL_VALUES <math>^a</math> || dimension for 1 data point (for the entire analysis)
|}
</div>
 
<math>^a</math> Dimension for variables of the size 1x1 for variables such as N_FFT_SEGMENTS and DOF. <br>
 
=Variables=
<div class="mw-collapsible mw-expand" data-collapsetext="Collapse" data-expandtext="Expand">
<br>
{| class="wikitable sortable"
|-
|-
| FLOWPS || 0 || flow_past_sensor || m s-1 || TIME_SPECTRA ||
! Parameter Name !! Req.<math>^a</math> !! Standard Name !! Units of measurement !! dimension
|-
|-
| PRES || 1<br /> 0 || sea_water_pressure<br /> water_pressure || dbar || TIME_SPECTRA ||
| TIME || R || time || [http://cfconventions.org/cf-conventions/cf-conventions CF-Convention]<math>^b</math> || TIME_SPECTRA  
|-
|-
| TIME || 1 || time || days since 1950-01-01 00:00:00 UTC || TIME_SPECTRA ||
| SECTION_NUMBER || R || unique_identifier_for_each_section_ of_data_from_timeseries || - || TIME_SPECTRA
|-
|-
| TEMP || 1<br /> 0 || sea_water_temperature<br /> water_temperature || degree_Celsius || TIME_SPECTRA ||
| PSPD_REL || R || platform_speed_wrt_[sea]<math>^c</math>_water || m s-1 || TIME_SPECTRA
|-
|-
| SECTION_NUMBER || 0 || || dimensionless || TIME_SPECTRA ||
| SH_SPEC || R || shear_probe_spectrum || s-2 cpm-1 || TIME_SPECTRA, N_WAVENUMBER, N_SHEAR_SENSORS
|-
|-
| SH_SPEC || || shear_probe_spectrum || s-2 cpm-1 || [TIME_SPEC, WAVENUMBER, n_shear_sensors] || from shear probes (dirty)
| KCYC || R || cyclic_wavenumber || cpm || TIME_SPECTRA, N_WAVENUMBER
|-
|-
| SH_SPEC_CLEAN || || shear_probe_spectrum_clean || s-2 cpm-1 || [TIME_SPEC, WAVENUMBER, n_shear_sensors] || cleaned using [[Goodman algorithm]]
| SH_SPEC_CLEAN || R || shear_probe_spectrum_clean || s-2 cpm-1 || TIME_SPECTRA, N_WAVENUMBER, N_SHEAR_SENSORS
|-
|-
| A_SPEC || || acceleration_sensor_spectrum || m2 s-4 cpm-1 || [TIME_SPEC, WAVENUMBER, n_acc_sensors] ||
| N_FFT_SEGMENTS || R || number_of_fft_segments || - || N_GLOBAL_VALUES
|-
|-
| AP_SPEC || || vibration_sensor_spectrum || NA || [TIME_SPEC, WAVENUMBER, n_vibration_sensors] ||
| N_VIB_SENSORS || R || number_of_vibration_sensors_used_for_cleaning_spectra || - || N_GLOBAL_VALUES
|-
|-
| SH_A_SPEC || || Complex cross-spectral matrix of shear and acceleration || || [TIME_SPEC, WAVENUMBER, ???] ||
| SPEC_STD || R || standard_deviation_uncertainty_of_shear_spectrum || - || N_GLOBAL_VALUES
|-
|-
| SH_AP_SPEC || || Complex cross-spectral matrix of shear and vibrations || || [TIME_SPEC, WAVENUMBER, ???] ||  
| PRES || HR || [sea]<math>^c</math>_water_pressure || dbar || TIME_SPECTRA
|-
|-
| KCYC || || Cyclic wavenumber || cpm || WAVENUMBER ||
| ACC_SPEC || O || acceleration_sensor_spectrum || m2 s-4 cpm-1 || TIME_SPECTRA, N_WAVENUMBER, N_ACCEL_SENSORS
|-
|-
| KMAX || || maximum_wavenumber || cpm || TIME_SPEC || maximum wavenumber for integration of shear spectrum
| VIB_SPEC || O || vibration_sensor_spectrum || - || TIME_SPECTRA, WAVENUMBER, N_VIB_SENSORS
|-
| SH_VIB_SPEC || O || shear_and_vibration_cross-spectral_matrix || - || TIME_SPECTRA, N_WAVENUMBER, N_SH_VIB_SPEC
|-
| SH_ACC_SPEC || O || shear_and_acceleration_cross-spectral_matrix || - || TIME_SPECTRA, N_WAVENUMBER, N_SH_ACC_SPEC
|-
| DOF || O || degrees_of_freedom_of_spectrum || - || N_GLOBAL_VALUES 
|}
|}
<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
</div>
[[Category: Shear probes]]
-----
Return [[Dataset requirements for shear probes]]<br>
go to previous: [[Level 2 data (shear probes)| Level 2 data]]<br>
go to next: [[Level 4 data (shear probes)| Level 4 data]].

Latest revision as of 19:56, 24 May 2024

Level 3 data contains the raw (and optionally cleaned) spectra derived from level 2 time series and is saved in the NetCDF group "L3_spectra". Level 3 parameters are defined along a new TIME dimension, which is the average time of the individual spectral segments. The length of the TIME dimension equals the number of spectral segments. Parameter for the calculation of the spectra, e.g. segment length, are provided in the meta data.


Dimensions


Dimension name description
TIME_SPECTRA length of the record of average times of spectral segments
N_WAVENUMBER length of the wavenumber array
N_SHEAR_SENSORS number of shear channels (shear sensors)
N_***_SENSORS number of *** channels
N_SH_ACC_SPEC number of shear-acceleration cross spectra
N_SH_VIB_SPEC number of shear-vibration cross spectra
N_GLOBAL_VALUES [math]\displaystyle{ ^a }[/math] dimension for 1 data point (for the entire analysis)

[math]\displaystyle{ ^a }[/math] Dimension for variables of the size 1x1 for variables such as N_FFT_SEGMENTS and DOF.

Variables


Parameter Name Req.[math]\displaystyle{ ^a }[/math] Standard Name Units of measurement dimension
TIME R time CF-Convention[math]\displaystyle{ ^b }[/math] TIME_SPECTRA
SECTION_NUMBER R unique_identifier_for_each_section_ of_data_from_timeseries - TIME_SPECTRA
PSPD_REL R platform_speed_wrt_[sea][math]\displaystyle{ ^c }[/math]_water m s-1 TIME_SPECTRA
SH_SPEC R shear_probe_spectrum s-2 cpm-1 TIME_SPECTRA, N_WAVENUMBER, N_SHEAR_SENSORS
KCYC R cyclic_wavenumber cpm TIME_SPECTRA, N_WAVENUMBER
SH_SPEC_CLEAN R shear_probe_spectrum_clean s-2 cpm-1 TIME_SPECTRA, N_WAVENUMBER, N_SHEAR_SENSORS
N_FFT_SEGMENTS R number_of_fft_segments - N_GLOBAL_VALUES
N_VIB_SENSORS R number_of_vibration_sensors_used_for_cleaning_spectra - N_GLOBAL_VALUES
SPEC_STD R standard_deviation_uncertainty_of_shear_spectrum - N_GLOBAL_VALUES
PRES HR [sea][math]\displaystyle{ ^c }[/math]_water_pressure dbar TIME_SPECTRA
ACC_SPEC O acceleration_sensor_spectrum m2 s-4 cpm-1 TIME_SPECTRA, N_WAVENUMBER, N_ACCEL_SENSORS
VIB_SPEC O vibration_sensor_spectrum - TIME_SPECTRA, WAVENUMBER, N_VIB_SENSORS
SH_VIB_SPEC O shear_and_vibration_cross-spectral_matrix - TIME_SPECTRA, N_WAVENUMBER, N_SH_VIB_SPEC
SH_ACC_SPEC O shear_and_acceleration_cross-spectral_matrix - TIME_SPECTRA, N_WAVENUMBER, N_SH_ACC_SPEC
DOF O degrees_of_freedom_of_spectrum - N_GLOBAL_VALUES

[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

Return Dataset requirements for shear probes
go to previous: Level 2 data
go to next: Level 4 data.

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