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.
Required Variables
| Parameter Name |
Standard Name |
Units of measurement |
dimension
|
| TIME |
time |
CF-Conventions compatible offset[math]\displaystyle{ ^a }[/math] |
TIME_SPECTRA
|
| SECTION_NUMBER |
unique_identifier_for_each_section_ of_data_from_timeseries |
- |
TIME_SPECTRA
|
| PSPD_REL |
platform_speed_wrt_sea_water |
m s-1 |
TIME_SPECTRA
|
| SH_SPEC |
shear_probe_spectrum |
s-2 cpm-1 |
[TIME_SPECTRA, N_WAVENUMBER, N_SHEAR_SENSORS]
|
| KCYC |
cyclic_wavenumber |
cpm |
[TIME_SPECTRA, N_WAVENUMBER]
|
| SH_SPEC_CLEAN[math]\displaystyle{ ^b }[/math] |
shear_probe_spectrum_clean |
s-2 cpm-1 |
[TIME_SPECTRA, N_WAVENUMBER, N_SHEAR_SENSORS]
|
| N_FFT_SEGMENTS |
number_of_fft_segments |
- |
N_GLOBAL_VALUES
|
| N_***_SENSORS[math]\displaystyle{ ^c }[/math] |
number_of_vibration_sensors_or_acceleration_channel_used_for_cleaning_spectra |
- |
N_GLOBAL_VALUES
|
| SPEC_STD |
standard_deviation_uncertainty_of_shear_spectrum |
- |
N_GLOBAL_VALUES
|
[math]\displaystyle{ ^a }[/math] i.e. "Days since YYYY-MM-DDT00:00:00Z"
[math]\displaystyle{ ^b }[/math] SH_SPEC_CLEAN must be included in the file if these spectra were used to compute [math]\displaystyle{ \varepsilon }[/math]
[math]\displaystyle{ ^c }[/math] VIB or ACC depending on what sensor is used to clean the spectra.
Optional Level 3 Variables
| Parameter Name |
Standard Name |
Units of measurement |
dimension
|
| PRES |
water_pressure |
dbar |
TIME_SPECTRA
|
| ACC_SPEC |
acceleration_sensor_spectrum |
m2 s-4 cpm-1 |
[TIME_SPECTRA, N_WAVENUMBER, N_ACCEL_SENSORS]
|
| VIB_SPEC |
vibration_sensor_spectrum |
- |
[TIME_SPECTRA, WAVENUMBER, N_VIB_SENSORS]
|
| SH_VIB_SPEC |
shear_and_vibration_cross-spectral_matrix |
- |
[TIME_SPECTRA, N_WAVENUMBER, N_SH_VIB_SPEC]
|
| SH_ACC_SPEC |
shear_and_acceleration_cross-spectral_matrix |
- |
[TIME_SPECTRA, N_WAVENUMBER, N_SH_ACC_SPEC]
|
| DOF |
degrees_of_freedom_of_spectrum |
- |
N_GLOBAL_VALUES
|
Return Dataset requirements for shear probes
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go to next: Level 4 data.
