input.param - a file containing input parameters
Care must be taken in setting up the input parameter list that values agree with those used in the valious shell scripts used (especially vel.sh and data.sh.)
NL = 651 , TH = 0.002 , THO = 2.70 ,
XMIN = -1. , XMAX = -1. ,
NT0 = 1024 , TL0 = 2.048 , TW0 = 2.4,
NT = 1024 , TL = 2.048 ,
NP0 = 49 , PMIN0 = 0.01 , PMAX0 = 0.49 ,
NP = 35 , NPI = 5 , NDP = 1 ,
IRICK = 0 , RCDEP = 0.0 , VW0 = 1.520 , POL = 1 ,
ITERMAX = 0 , COST0 = 1.E-10 , CD = 0.0025 , CM = 1. ,
F1 = 0.08 , F2 = 0.14 , F3 = 0.40 , F4 = 0.60 ,
NORM = .F. , RADS = .004 , PCG = .F. ,
DGEN = .F. , VISU = .F. , NRUN = 1 ,
IOBH = 0 ,
| Parameter Definitions|
Note (WSH 4Oct00): Certain parameters are limited in size. For example, if NT > 1024, the program must be recompiled after editing the value for ntm in inv1d.dim
- NL = Number of Layers, including half-space - can be determined by running vel.sh
- TH = Thickness of the layers (should be constant) (km)
- THO = Thickness of water layer (km) - must match that used in vel.sh
- XMIN = Minimum offset (km) - not used if set to -1
- XMAX = Maximum offset (km) - not used if set to -1
Note: XMIN and XMAX are ordinarily used to determine what part of tau-p space to use in comparison to the synthetic data if the real data are limited in x-range.
- NT0 = The total number of time points of the data - must be a power of 2
- TL0 = The total length of the time series (s)
- TW0 = The time delay (starting time of first sample) - must be the same as t0 in data.sh
- NT = The total number of time points of the data used for inversion - must be a power of 2
- TL = The total length of the time series (s) used for inversion
- NP0 = The total number of traces in the data file
- PMIN0 = The minimum value of the slowness (s/km)
- PMAX0 = The maximum value of the slowness (s/km)
- NP = The total number of traces used for inversion
- NPI = The number of the first trace used for inversion
- NDP = The the number of traces skipped between two traces for inversion - to invert all traces, set to 1
- ITERMAX: The maximum no. of iteration for inversion - 1st test to stop the algorithm. If ITERMAX = 0 then only the forward calculation is performed; there will be no iteration (set this way for the /prep/ stage but not for the /inv/ stage.)
- COST0 : Cutoff value under which the recursion will stop - second test to stop the algorithm.
- CD : Covariance of the data. Constant element of the diagonal of the covariance of the data. 0.5 used by Jun Korenaga - determined empirically.
- CM : Covariance of the model. Constant element of the diagonal of the covariance of the model. 1.0 used by Jun Korenaga - determined empirically.
- F1-F4 : Definition of the band-pass filter in frequency as a fraction of Nyquist.
F1 > Lower pass (0) 1_ _ _ _______ _ _ _1
F2 > " " (1) /| |\
F3 > Upper pass (1) 0_ ___/_|_ _ _|_\___ _0 ->Freq.
F4 > " " (0) | | | | | |
as fraction of Fmax 0 F1 F2 F3 F4 Fmax=1
No filtering if Fi=-1, i=1,2,3 or 4
Iterative runs with increasing frequency and slowness ranges.....
- NORM = .TRUE. Normalisation of the data to adapt to the energy of the synthetic seismogram - ignored in the current version of the program.
- RADS : Applicable if NORM=.TRUE. Amplitude agreement between the real and synthetic data. Will be equal to unity in proximity to the real model. (RADS.GE.1)
- PCG = .TRUE. Preconditioning of the gradient to enhance the amplitude of the perturbation of the deeper model.
- DGEN = .TRUE. Creation of the Omega-P data corresponding to the initial model (written on unit 49) - ignored in the current version of the program
- VISU = .FALSE.
- NRUN : Number of the run of inversion with the same data set. (Used only for output information.)
- IOBH = 1 - use OBH geometry (modification by Korenaga)
- inv.sh - do-all-the-stuff script. This calls the N run?.sh scripts, where ? is an integer from 1 to N. N is the number of runs desired for a particular inversion. In general, a good approach to the inversion is to start with a small window of slownesses and frequencies and then progress to a full range of slowness and frequencies for the given data set.
- run?.sh - run script for each step. These N files control the parameters for a given inversion run. The values here must mach those found in input.param.run?.
- N.B. For each run of inv1d, the following input files are required:
- wpfile - created by data.sh in ../../prep/run_x.
- src.fft - created by src.sh in ../../prep/run_x.
Notes on input.param.run?
- Be sure that the parameters here correspond to those used for ../../prep/run_x. A few additional concerns are required:
- NP, NPI, and NDP will need to be redefined (for each run of the inversion).
- ITERMAX = 9 (anything more than 5 or 6 is likely fine; this can be determined empirically.)
- F1 ... F4 - use only low frequency part of the data for the first run and expand to higher frequencies for later runs.
- NZMIN = 16 - this stops the inversion from varying anything abover the 16th layer to avoid near sea floor effects. Be sure to change this parameter if the depth sample interval is changed back in the tau-p transform step.
Calculating the results
Creates files for printing with GMT and calculates statistics
- run.sh - similar to run_x script in ../ but adds conversion of the results to segy format and prints them using plot.sh.
- misfit.sh - calculates the following information and places it in a file named chi.tmp. Requires a file named box.aroundbsr.xtp which windows the data to be used in the calculation.
- csum_count - number of data
- csum: - misfit (this is what you want)
- corr: - correlation.
Plotting the results
Plots the data with GMT
- gmt-taup.wsyn.sh - GMT script for plotting.
Last updated: 11 September 2003
A. R. Gorman(firstname.lastname@example.org)