[gradsusr] Vertical Integrated Moisture Transport (VIMT)

[Muhammad Latif]

Hi all,

I am trying to calculate Vertical Integrated Moisture Transport (VIMT) from surface to 500 hPa in units of kg/m/sec using grads function "vint(psexpr,expr,top)" only on the one time step.
I used the following script to get VIMT:

'sdfopen spr-daily.nc'         ;* spr is the surface pressure in Pa.

'set time 20jun1970'
'define surfpres=pres/100'     ;* /100 to convert in hPa
'close 1'

'sdfopen shum-daily.nc'
'sdfopen uwnd-daily.nc'
'sdfopen vwnd-daily.nc'

'set lat 0 45'
'set lon 50 100'

'set time 20jun1970'
'define vintq=vint(surfpres,shum.1,500)'     ;*shum is the specific humidity in kg/kg
'define vintu=vint(surfpres,uwnd.2,500)'     ;*uwnd is the u component of wind in m/sec
'define vintv=vint(surfpres,vwnd.3,500)'     ;*vwnd is the v component of wind in m/sec
'define zon=(vintq*vintu)'
'define mer=(vintq*vintv)'

'set gxout vector'
'd zon;mer'

Script runs successfully showing VIMT, but the magnitude of vector appears (4e+06) in the vector scale bar.
I guess, this magnitude is not right. The value should lie around 20 or 40 (kg/m/sec). 

I'll be very thankful if anyone could help me to sort out the issue mentioned above.

Regards

Muhammad Latif
PhD Scholar
Department of Meteorology
CIIT, Islamabad 
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