how can I print the coordinate information of the array in WRF OUTPUT FILE in NC format ?

here I want to indict or print the coordinate information of the array in
WRF OUTPUT FILE.
For example:

I have such a wrf with the variables:
Variable: U
Type: float
Total Size: 26680320 bytes
            6670080 values
Number of Dimensions: 4
Dimensions and sizes: [Time | 6] x [bottom_top | 30] x [south_north | 192]
x [west_east_stag | 193]
Coordinates:
            Time: not a coordinate variable
            bottom_top: not a coordinate variable
            south_north: not a coordinate variable
            west_east_stag: not a coordinate variable
Number of Attributes: 6
  FieldType : 104
  MemoryOrder : XYZ
  description : x-wind component
  units : m s-1
  stagger : X
  coordinates : XLONG_U XLAT_U

I want to print the bottom_top information.
aa=wrffile->U
print(aa&bottom_top )
But the error message said that :
fatal:No coordinate variable exists for dimension (bottom_top) in variable
(aa)

Here how may I to print and modify the information of bottom_top ?

-- 
TANG Jie
Email: totangjie@gmail.com
Tel: 0086-2154896104
Shanghai Typhoon Institute,China

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Received on Mon Feb 20 08:32:23 2012