Vertical interpolation: sigma to pressure levels

Dear NCL-Users,

I am trying to use vertical interpolation (vinth2p) for the CFS output variables, having 64 sigma levels.
My code is as follows:

 ps = f1->PRES_GDS4_SFC ; Surf. pressure in Pa

 data = f2->MIXR_GDS4_HYBL(:,:,:,:)
 datai = data(:,::-1,:,:) ; Top-to-Bottom

 plevs = (/1000,975,950,925,900,875,850,800,700,600,500,400,300,250,200,150,100/)

 sigma = (/.99733, .99165, .98521, .97794, .96973, .96049, .95011, .93849,\
            .92551, .91107, .89506, .87739, .85797, .83674, .81366, .78872,\
            .76194, .73340, .70319, .67148, .63846, .60437, .56950, .53415,\
            .49863, .46329, .42843, .39437, .36138, .32970, .29953, .27102,\
            .24429, .21939, .19635, .17517, .15579, .13815, .12218, .10778,\
            .09483, .08324, .07289, .06367, .05549, .04823, .04182, .03615,\
            .03115, .02675, .02288, .01948, .01649, .01387, .01157, .00956,\
            .00780, .00625, .00490, .00372, .00269, .00179, .00099, .00027 \
           /)

  hybm = sigma(::-1) ; Reversing Top-to-Bottom
  hyam = hybm*0.0

  x = vinth2p(datai,hyam,hybm,plevs,ps,1,1000,1,True)

But the output variable (x) contains some -ve values, while actual data is always +ve.
Is there any problem in the code?
Or is it because of assumed "hyam" = 0.0?

Thanks in advance for your kind suggestion.

Regards,
Abhik.

___________________________________________

Abhik Santra
CSIR Research Fellow,
Indian Institute of Tropical Meteorology,
Pune - 411008.
India
___________________________________________

_______________________________________________
ncl-talk mailing list
List instructions, subscriber options, unsubscribe:
http://mailman.ucar.edu/mailman/listinfo/ncl-talk
Received on Sat May 03 02:38:41 2014