I want to calculate vertically integrated moisture flux convergence (VIMFC) in GrADS.

But when I give the following instruction it marks me errors:

sdfopen shum.mon.mean.nc
sdfopen uwind.mon.mean.nc
sdfopen vwind.mon.mean.nc

set lon 180 320
set lat 0 60
set t 763 766
set lev 1000 300


d vimf

ga-> qu=vint(1000, shum.1*uwnd.2,600)

Error from VINT:

Incompatible grids.
*** glibc detected *** grads: double free or corruption (!prev): 0x0000000003707c40 ***
======= Backtrace: =========

======= Memory map: ========
00400000-00bcb000 r-xp 00000000 08:05 1573111
7f898bdc2000-7f898bdc3000 r--p 00017000 08:05 1572886                    /lib/x86_64-linux-gnu/libpthread-2.15.soAborted (core dumped)

Does anyone know how to fix it?

Best, Pablo Camarena

  • 1
    $\begingroup$ have you checked the grids of your input files to see if they match? It does say "Incompatible grids." $\endgroup$
    – f.thorpe
    May 31 '17 at 3:01
  • $\begingroup$ That'd be my first guess too. I remember GrADS being annoyingly uninformative during errors like yours $\endgroup$ May 31 '17 at 6:02
  • $\begingroup$ I have come across the same problem. Some time ago, I have started using Matlab and R. Things have become more transparent. For some starting reference, I suggest taking a look at this topic: earthscience.stackexchange.com/a/10667/8396 $\endgroup$
    – ouranos
    Jun 28 '17 at 13:53

you can use this: this define integrated vapor transport(IVT) or Moisture Flux:

 'define qu=vint(const(lon,1000,-a),shum.1*uwind.2,300)'  
 'define qv=vint(const(lon,1000,-a),shum.1*vwind.3,300)'  
 'define VIMFC=mag(qu,qv)'
 'd VIMFC'

best regards

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