Level 3 data (shear probes)

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. This also equals time of dissipation estimates.
N_WAVENUMBER	length of the wavenumber array
N_SHEAR_SENSORS	number of shear channels (shear sensors)
N_***_SENSORS	number of *** channels (such as ACC and VIB)
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] This dimension is 1x1. Use, for example, for N_FFT_SEGMENTS (number_of_fft_segments), SPEC_STD (standard_deviation_uncertainty_of_shear_spectrum), and is one value for the entire analysis.

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

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