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1) In the Lagranto folder you shoud have the following files and directories: 

rossby.ethz.ch[229]: ls -l
drwxr-xr-x 3 michaesp wheel 2048 Apr  5 13:31 bin/
drwxr-xr-x 3 michaesp wheel 1024 Apr  5 13:31 caltra/
drwxr-xr-x 7 michaesp wheel 1024 Apr  4 16:57 docu/
drwxr-xr-x 5 michaesp wheel 1024 Apr  4 16:57 figure/
drwxr-xr-x 3 michaesp wheel 4096 Apr  5 13:31 goodies/
-rwxr-xr-x 1 michaesp wheel 8738 Apr  5 12:01 install.csh*
drwxr-xr-x 3 michaesp wheel 1024 Apr  5 13:31 lib/
drwxr-xr-x 3 michaesp wheel 1024 Apr  5 13:31 select/
drwxr-xr-x 3 michaesp wheel 1024 Apr  5 13:31 trace/


2) If you haven't done so, you should then install Lagranto with

> ./install.csh all

and at the end all Fortran programs should be compiled and linked within the <bin> directory.


3) The next step is to prepare all files for a Lagranto run. In my case, this looks as follows:

rossby.ethz.ch[234]: ls -l
lrwxrwxrwx 1 michaesp wheel        30 Mar 25 14:53 P20110826_12 -> wrfout_d01_2011-08-26_12:00:00
lrwxrwxrwx 1 michaesp wheel        30 Mar 25 14:54 P20110826_13 -> wrfout_d01_2011-08-26_12:01:00
lrwxrwxrwx 1 michaesp wheel        30 Mar 25 14:54 P20110826_14 -> wrfout_d01_2011-08-26_12:02:00
lrwxrwxrwx 1 michaesp wheel        30 Mar 25 14:54 P20110826_15 -> wrfout_d01_2011-08-26_12:03:00
lrwxrwxrwx 1 michaesp wheel        30 Mar 25 14:54 P20110826_16 -> wrfout_d01_2011-08-26_12:04:00
lrwxrwxrwx 1 michaesp wheel        30 Mar 25 14:54 P20110826_17 -> wrfout_d01_2011-08-26_12:05:00
-rw-r--r-- 1 michaesp wheel  11676728 Apr  5 13:31 wrfmap.nc
-rw-r--r-- 1 michaesp wheel 101793120 Mar 11  2013 wrfout_d01_2011-08-26_12:00:00
-rw-r--r-- 1 michaesp wheel 101793120 Mar 11  2013 wrfout_d01_2011-08-26_12:01:00
-rw-r--r-- 1 michaesp wheel 101793120 Mar 11  2013 wrfout_d01_2011-08-26_12:02:00
-rw-r--r-- 1 michaesp wheel 101793120 Mar 11  2013 wrfout_d01_2011-08-26_12:03:00
-rw-r--r-- 1 michaesp wheel 101793120 Mar 11  2013 wrfout_d01_2011-08-26_12:04:00
-rw-r--r-- 1 michaesp wheel 101793120 Mar 11  2013 wrfout_d01_2011-08-26_12:05:00

The files <wrfout*> are from WRF output; I link these files to the corresponding P{yyyymmdd_hh} files, 
the format and naming requested by Lagranto. Finally, there is an important auxiliary file <wrfmap.nc> which 
is needed for the conversion between latitude/longitude coordinates and WRF grid coordinates.


4) For tests you can find the files liste in 3) on our FTP server: <ftp://iacftp.ethz.ch/pub_read/sprenger/lagranto.wrf.test/>. 
It might be worthwile to do a first sample run based on these files. Then we certainly know that the basic installation is ok :-)


5) An important file is the <wrfmap.nc> which includes the transformation between longitude/latitude and x/y coordinates. 
All calculations are done in WRF's x/y space, but at the beginning or end of a calculation you might want to convert from 
or to geographical lon/lat coordinates. Please consult the manual page for this command (included in the WRF docu folder):

> lagrantohelp wrfmap

or if this doesn't work:

> nroff -man lagranto.wrf/docu/man/wrfmap.0


6) Here are some first steps in running Lagranto with WRF. First, you have to create a start position file, which lists 
the longitude, latitude and height of the starting position of the trajectory:

> more startf.ll
-70 45 5000

In a next step you should convert this start position into WRF coordinates:

> wrfmap -ll2xy startf.ll startf.xy
> more startf.xy
Reference date    00000_0000 / Time range       0 min

  time        x       y     z
-----------------------------

   0.00   107.66  131.30  5000

At the moment the reference time (corresponding to time 0 of your trajectory) is not correctly set. Could you do this, 
at the moment, manually. The modified file in my case looks then as follows:

> more startf.xy
Reference date 20110826_1200 / Time range       0 min

  time        x       y     z
-----------------------------

   0.00   107.66  131.30  5000

Wit this minor correction Lagranto should run. Here is the call and the corresponding output:

> caltra 20110826_12 20110826_17 startf.xy trajectory.xy
> more trajectory.xy
Reference date 20110826_1200 / Time range     300 min

  time        x       y     z
-----------------------------

   0.00   107.66  131.30  5000
   1.00   109.71  130.91  4886
   2.00   111.79  130.80  4746
   3.00   113.89  130.98  4788
   4.00   116.03  131.46  4847
   5.00   118.21  132.26  4810

The position (x/y) of the air parcel is given in WRF coordinates; to get them back into lon/lat, you can use 
again <wrfmap>:

> wrfmap -xy2ll trajectory.xy trajectory.ll
> more trajectory.ll
Reference date 20110826_1200 / Time range     300 min

  time      lon     lat     z
-----------------------------

   0.00   -70.00   44.99  5000
   1.00   -69.32   44.86  4886
   2.00   -68.62   44.78  4746
   3.00   -67.91   44.78  4788
   4.00   -67.18   44.84  4847
   5.00   -66.42   44.97  4810

That's it! Now would come tracing of fields along trajectories and/or selection of trajectories. But these 
steps can wait until you could reproduce all steps above :-) Let me know about your progress ;-)