gribmap命令使用

tmw

ctl文件如下：
dset fnl_0807%d2_%h2_00
dtype grib 3
options template yrev
index avn.map
undef -9.99e33
title MRF IC = 00Z may 28, 2003
xdef 360 linear 0 1
ydef 181 linear -90 1
zdef 26 levels 1000 975 950 925 900 850 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 70 50 30 20 10
tdef 8 linear 00z01JUL08 6hr
vars 62
z  26  7,100  Geopotential Height
u  26  33,100  U Winds
v  26  34,100  V Winds
t  26  11,100  Temperature
vv  26  39,100  Pressure Vertical Velocity
rh  26  52,100  Relative Humidity
vort  26  41,100  Absolute Vorticity
bu  0  33,116,30,0  U Winds, Bottom 30mb
bv  0  34,116,30,0  V Winds, Bottom 30mb
bt  0  11,116,30,0  Temperature, Bottom 30mb
brh  0  52,116,30,0  Relative Humidity, Bottom 30mb
grads中如何读取index avn.map这一行啊