[ncl-talk] potential vorticity, error of " division by 0"

[Nafiseh Pegahfar]

I write a ncl code to calculate PV(potential vorticity) at 300 mb using
gfs data.
after running I recievd the error of
""""""""""""""""""""""""""""""""""""""""""""""""""""""""
fatal:divide: Division by 0, Can't continue
fatal:Div: operator failed, can't continue
fatal:["Execute.c":8575]:Execute: Error occurred at or near line 3892 in
file /usr/share/ncarg/nclscripts/csm/shea_util.ncl

fatal:["Execute.c":8575]:Execute: Error occurred at or near line 3909 in
file /usr/share/ncarg/nclscripts/csm/shea_util.ncl

fatal:["Execute.c":8575]:Execute: Error occurred at or near line 133 in
file PVcode_version6_3.ncl
"""""""""""""""""""""""""""""""""""""""""""""""""""""""'''

I checked 3892 line in shea_util.ncl it was "con = R/(s*conform(t,p,npr))"
while s= -(t/theta)*dthdp. I checked "s","t","theta","dthdp" and
"conform(t,p,npr)". non of them was zero.

please help me what to do.
some of my code is :

U_00   = a->UGRD_P0_L100_GLL0(:,::-1,:) ; (time,lev,lat,lon) or
(lev,lat,lon) V_00   = a->VGRD_P0_L100_GLL0(:,::-1,:)   ;
(time,lev,lat,lon) or
(lev,lat,lon)
T_00   = a->TMP_P0_L100_GLL0(:,::-1,:) ; K
P_00   = (a->lv_ISBL0)
P_00   = (P_00)*100
P_00 at units = "Pa"
m=dimsizes(P_00)
print ("dimsizes(P_00)="+dimsizes(P_00))

L = T_00&lat_0

;"""""""""""""""""""""""""""""""""""""""""""""
;check "conform(T_00,P_00,0)"
;""""""""""""""""""""""""""""""""""""""""""'
conform_00=conform(T_00,P_00,0)
test=0.0
conform_00_zero_test = where(conform_00.eq.0, test+5, test)
print("test="+test)

;"""""""""""""""""""""""""""""""""""""""""""""
;check  "s= -(t/theta)*dthdp"
;""""""""""""""""""""""""""""""""""""""""""'
theta_test=0.0
theta_00= T_00*(100000./conform(T_00,P_00,0))^0.286
;print("theta_00="+theta_00)
theta00_zero_test = where(theta_00.eq.0, theta_test+5, theta_test)
print("theta_test="+theta_test)

T_test=0
T00_zero_test = where(T_00.eq.0, T_test+5, T_test)
print(" T_test="+ T_test)
;print("T_00="+T_00)

dthdp_test=0
dthdp_00 = center_finite_diff_n (theta_00,P_00,False,0,0)
dthdp_00_zero_test = where(dthdp_00.eq.0, dthdp_test+5, dthdp_test)
print("dthdp_test="+dthdp_test)
;print("dthdp_00="+dthdp_00)
;""""""""""""""""""""""""""""""""""""""""""""""""""""""""""'

PV_00 = pot_vort_isobaric(P_00 ,U_00 ,V_00 ,T_00 ,L , 1, 0)
printVarSummary (PV_00)
PV_00_300 = PV_00 ({3000000},:,:)
print ("PV_00_300"+PV_00_300)


=================================
Best Regards
Nafiseh Pegahfar
Assistant Professor
Iranian National Institute for Oceanography and Atmospheric Science
(http://www.inio.ac.ir)
Phone: (0098)21- 66944873-5 Ext. 315
Fax: (0098)21- 66944869
Email: (pegahfar at ut.ac.ir)
          (pegahfar at inio.ac.ir)
=================================



=================================
Best Regards
Nafiseh Pegahfar
Assistant Professor
Iranian National Institute for Oceanography and Atmospheric Science
(http://www.inio.ac.ir)
Phone: (0098)21- 66944873-5 Ext. 315
Fax: (0098)21- 66944869
Email: (pegahfar at ut.ac.ir)
          (pegahfar at inio.ac.ir)
=================================