Spectra Parameters

Please note: PALM spectra are normalized by the variance of the respective quantity at the corresponding height level. In addition, the spectra output is internally multiplied by the respective wavenumber.

NAMELIST group name: spectra_par

Parameter Name	FORTRAN Type	Default Value	Explanation
averaging_interval_sp	R	value of averaging _interval	Averaging interval for spectra output to local file DATA_1D_SP_NETCDF (in s). If this parameter is given a non-zero value, temporally averaged spectra data are output. By default, spectra data are not subject to temporal averaging. The interval length is limited by the parameter dt_dosp. In any case averaging_interval_sp <= dt_dosp must hold. If an interval is defined, then by default the average is calculated from the data values of all time steps lying within this interval. The number of time levels entering into the average can be reduced with the parameter dt_averaging_input_pr. If an averaging interval can not be completed at the end of a run, it will be finished at the beginning of the next restart run. Thus for restart runs, averaging intervals do not necessarily begin at the beginning of the run.
comp_spectra_level	I(100)	no level	Vertical level for which horizontal spectra are to be calculated and output (in grid points). Spectra can be calculated for up to 100 levels.
data_output_sp	C*10 (10)	10 * ' '	Quantities for which horizontal spectra are to be calculated and output. Allowed standard values are: data_output_sp = 'u', 'v', 'w', 'pt', 'q', 's', . The user may define further quantities. Spectra are calculated using the FFT-method defined by fft_method. Attention: Computation of spectra is currently not possible with fft_method = 'fftw'. By default, spectra data are output to the local file DATA_1D_SP_NETCDF. The file's format is netCDF and can be visualized by any graphic software which provides a netCDF interface (e.g. NCL, ​ferret or ​ncview). The temporal interval of the output times of profiles is assigned via the parameter dt_dosp. The vertical levels for which spectra are to be computed and output must be given by parameter comp_spectra_level. Note: Beside, data_output_sp, values must be given for comp_spectra_level and spectra_direction, otherwise, no output will be created! Calculation of spectra requires cyclic boundary conditions along the respective directions (see bc_lr and bc_ns). The spectra are ordered with respect to their output times. Spectra can also be temporally averaged (see averaging_interval_sp). Each data point of a spectrum is output in a single line (1st column: wavenumber, 2nd column: spectral coefficient). If spectra are to be calculated and output for more than one height (see comp_spectra_level), the spectral coefficients for the further heights can be found in the subsequent columns. The order of the data in the file follows the order used in the assignment for data_output_sp (data_output_sp = 'u', 'v',… means that the file starts with the spectra of the u-component, followed by the v-component spectra, etc.).
dt_dosp	R	value of dt_data _output	Temporal interval at which spectra data shall be output (in s). If output of horizontal spectra is switched on (see data_output_sp), this parameter can be used to assign the temporal interval at which spectral data shall be output. Output can be skipped at the beginning of a simulation using parameter skip_time_dosp, which has zero value by default. Reference time is the beginning of the simulation, i.e. output takes place at times t = skip_time_dosp + dt_dosp, skip_time_dosp + 2*dt_dosp, skip_time_dosp + 3*dt_dosp, etc. The actual output times can deviate from these theoretical values (see dt_dopr). If dt_dosp < dt, then spectral data are output after each time step (if this is requested it should be dt_dosp = 0).
skip_time_dosp	R	value of skip_time _data_output	No output of spectra data before this interval has passed (in s). This parameter causes that data output activities are starting not before this interval (counting from the beginning of the simulation, t=0) has passed. Example: If the user has set dt_dosp = 3600.0 and skip_time_dosp = 1800.0, then the first output will be done at t = 5400 s.
spectra_direction	C*2 (10)	10 * ' '	Direction(s) along which spectra are to be calculated. Allowed values are 'x' , 'y' and 'xy' . For every quantity given by data_output_sp a corresponding direction must be assigned. Calculation of spectra requires cyclic boundary conditions along the respective directions (see bc_lr and bc_ns).