Changes between Initial Version and Version 1 of ToolsAndUtilities/Sfvp


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Timestamp:
29/04/13 10:02:44 (7 years ago)
Author:
ros
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Content copied over from climate wiki

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  • ToolsAndUtilities/Sfvp

    v1 v1  
     1= SFVP = 
     2 
     3`sfvp` is a program that can calculate the Stream function and numerous other fields from basic U and V wind components (Please note: AVAILABLE ONLY FOR UNIVERSITY OF READING Researchers). To get access to the `sfvp` executable run 
     4{{{ 
     5setup umtools 
     6}}} 
     7Running `sfvp` without arguments will print this help information: 
     8{{{ 
     9These are the instructions for sfvp 
     10 
     11Usage:sfvp fn1 vn1 fn2 vn2 opfn 
     12 
     13Description: 
     14Calculates streamfunction and velocity potential 
     15on the sphere, given inputs of the two velocity 
     16components on the UM velocity grid 
     17}}} 
     18 
     19 
     20sfvp outputs: 
     21{{{ 
     22u 
     23v 
     24du/dx 
     25du/dy 
     26dv/dx 
     27dv/dy 
     28vorticity 
     29divergence 
     30stream function 
     31velocity potential 
     32tvor (?) 
     33tdiv (?) 
     34}}} 
     35 
     36== Notes == 
     37 
     38 * Input data files need to be in netCDF format. 
     39 
     40 * `sfvp` only really likes 4d files. To convert a 3d file to a 4d file (by inserting a dummy axis) use `~dan/idl/conv3d4d.pro` 
     41 
     42 * I've semi-automated the process of calculating `seasonal_means` and `ensemble_mean_seasonal_means` from the output of `sfvp`. The script that does this lives at `/home/dan/data/UM_DATA/SFcalc` 
     43 
     44 * If you get this error: `POISSON ERROR - WRONG LATITUDE FROM NCNS2G; ABORT` Then it is probably because your lattitude axis is the wrong way around. `sfvp` seems to prefer positive to negative, rather than vice versa. You can fix this by transforming the axis using `xconv`. Using `xconv` to do this may interpolate the data and change the latitude coordinate values, a better way is to use the nco tool [http://nco.sourceforge.net/nco.html#ncpdq-netCDF-Permute-Dimensions-Quickly ncpdq] this will invert the latitude axis without interpolation or changing the coordinate values. An example of ncpdq usage is, `ncpdq -a -latvar file.nc file_latswap.nc`, where `latvar` is the name of the netCDF latitude dimension.