ncl画600hPa风场图为什么只有纬向风求助啊

DABEIGE

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load"$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
f1=addfile("C:/Users/Administrator/Desktop/data/uv.1987.nc","r")
U=f1->u(3,:,:)
V=f1->v(3,:,:)
lat=f1->latitude
lat@units = "degrees_north"
lon=f1->longitude
lon@units= "degrees_east"
wks = gsn_open_wks("X11","11")
vcres                         = True
vcres@vcRefAnnoOrthogonalPosF = -1.0             ; move ref vector up
vcres@vcRefMagnitudeF         = 5             ; define vector ref mag
vcres@vcRefLengthF            = 0.045            ; define length of vec ref
vcres@vcGlyphStyle            = "CurlyVector"    ; turn on curly vectors
vcres@vcMinDistanceF          = 0.017

vcres@gsnAddCyclic=False;map 设置
vcres@mpMaxLatF = 50
vcres@mpMinLatF = 0
vcres@mpMaxLonF = 120
vcres@mpMinLonF = 50
vector = gsn_csm_vector_map(wks,U,V,vcres)