NCL将NAN改为缺测

value = 1.e20
ff=addfile(files1,'r')
temp=ff->temp({25:40},{70:110})
；-----方式1（可行）---------
swc =where(isnan_ieee(swc), value , swc)
swc@_FillValue = value
；----------方式2（待确认）----------
if (any(isnan_ieee(temp))) then
replace_ieeenan (temp, value, 0)
temp@_FillValue = value
end if