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27.1 Program CODAQ_AREA

CODAQ outputs the Q-values at midpoints between station and events. CODAQ_AREA reads this output and, at each frequency, average Q-values in user defined lat-lon bins. In each bin, provided there is enough data, the Q relation \bgroup\color{black}$ q = q0*f**v$\egroup is also calculated. The values in each bin is listed in an output file which can be displayed to get an approximate idea of the areal Q-distribution.

Input files: It is assumed that codaq.area exists so this name is hardwired. The corresponding codaq1.out is also used to get the frequencies used.

The interactive options are:

Min no for grid average, min no of freq for Q0 calculation: Minimum number of Q-values in a bin in order to do an average for that bin, minimum number of frequencies for which Q was calculated in a particular bin in order to calculate Q-relation.

Latitude range and grid size: Longitude range and grid size: Range to use and size of grid in degrees, can be a fraction of a degree.

The interactive options can be stored in a file called codaq_area.inp. If the file is present, input will be read from that file and no questions asked.

Example run:

C:\>codaq\_area
Frequencies    1.00    2.00    4.00    8.00   12.00   16.00
 Min no for grid average, min no of freq for Q0 calculation
3 4
 Lattitude range and grid size
-34 -28 1
 Longitude range and grid size
-71 -66 1
 Number of q-data in input file        1094
 Number of q-data inside grid           560


 File with areagrid:    codaq_area.out
 File with grid points: codaq_grid.out

Part of areal output file coda_area.out showing the lat-lon bins, note the midpoint of the bin is used:

freq=   1.0000000    
       -70.5 -69.5 -68.5 -67.5 -66.5
 -28.5     0     0     0    49    48
 -29.5     0     0    88     0     0
 -30.5     0     0    42     0     0
 -31.5     0     0    61     0     0
 -32.5     0    57    55     0     0
 -33.5     0     0    67     0     0
 freq=   2.0000000    
       -70.5 -69.5 -68.5 -67.5 -66.5
 -28.5     0     0     0   120   117
 -29.5     0     0   115     0     0
 -30.5     0     0   131     0     0
 -31.5     0     0   111     0     0
 -32.5     0   110   145     0     0
 -33.5     0     0     0     0     0

In addition, Q0 is also calculated in the gridpoints for a fixed Qalpha. The fixed Qalpha is taken from the average value for the whole area as given in file codaq1.out. The intention with this output is to get a more smooth picture of Q0 when Qalpha is not allowed to vary.

Output file codaq_grid.out contains details of the averages in each bin see part of file below:

freq=   1.0000000
   -33.500   -70.500       0.0       0.0         0
   -33.500   -69.500       0.0       0.0         1
   -33.500   -68.500      67.1      20.6         8
   -33.500   -67.500       0.0       0.0         0
   -33.500   -66.500       0.0       0.0         0

The output is: Bin midpoint, average Q, standard deviation in average and number of points in bin.


next up previous contents index
Next: 27.2 Program QSTAT Up: 27. Calculation of coda Previous: 27.0.4 General recommendations   Contents   Index
Peter Voss : Mon Feb 27 10:16:12 UTC 2017