NCL

cpp803520

用NCL做掩膜处理，程序如下：
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"
begin
a = addfile("MOD15A2.A2008057.h25v03.005.2008068113323.hdf","r")
lai1 = a->Lai_1km
if (lai1 .le.    80) then
  lai = lai1
    else
  lai  = lai1*0
end if
b = addfile("new.hdf","c")
b->LAI = lai
end
报错信息如下：
Copyright (C) 1995-2013 - All Rights Reserved
University Corporation for Atmospheric Research
NCAR Command Language Version 6.1.2
The use of this software is governed by a License Agreement.
See http://www.ncl.ucar.edu/ for more details.
fatal:Conditional statements (if and do while) require SCALAR logical values, see all and any functions
fatal:["Execute.c":8128]:Execute: Error occurred at or near line 13 in file ym.ncl


不懂是为什么，看了好多别人的程序都是这样写的啊？求指点