'set lev 1000 200'
'W=7.292E-5'
'G=9.80616'
'AT=6371221.3'
'DEG2RAD=3.141592654/180'
'F=2*W*SIN(lat*DEG2RAD)'
'DX=AT*COS(LAT*DEG2RAD)*CDIFF(LON,X)*DEG2RAD'
'DY=AT*CDIFF(LAT,Y)*DEG2RAD'
'UG=-G/F*CDIFF(Z,Y)/DY'
'VG= G/F*CDIFF(Z,X)/DX'
'div=hdivg(u,v)'
'divg=hdivg(ug,vg)'
'un=u-ug'
'vn=v-vg'
'divn=hdivg(un,vn)'
'clear'
'set lev 500'
'set gxout shaded'