The full resolution gridded ERA data (datasets ds115.3, ds115.5, ds115.6)
are on a reduced Gaussian grid.  This grid is like a Gaussian grid, except
that the number of points per latitude line varies with latitude.  (The
number of points along a longitude line is always the same.)

The table below gives the number of points for each latitude circle.
They are numbered from 1 at the northernmost (89.141 degrees), through 160 
at the southernmost (-89.141 degrees) parallel. 

To convert the reduced gaussian grid to a regular grid, call 
GRIBEX with HOPER = 'R'.  This calles the routine QU2REG2
which interpolates the reduced grid to a regular grid.

 Data represent type = gaussian     (Table 6)         4
 Number of points along a parallel varies.
 Number of points.   Parallel. (North to South)
    18                  1       
    25                  2       
    36                  3       
    40                  4       
    45                  5       
    54                  6       
    60                  7       
    64                  8       
    72                  9 to  10
    80                 11       
    90                 12       
    96                 13       
   100                 14       
   108                 15       
   120                 16 to  17
   128                 18       
   135                 19       
   144                 20 to  21
   150                 22       
   160                 23 to  24
   180                 25 to  27
   192                 28 to  29
   200                 30 to  31
   216                 32 to  34
   225                 35 to  36
   240                 37 to  39
   256                 40 to  43
   288                 44 to  52
   300                 53 to  56
   320                 57 to 104
   300                105 to 108
   288                109 to 117
   256                118 to 121
   240                122 to 124
   225                125 to 126
   216                127 to 129
   200                130 to 131
   192                132 to 133
   180                134 to 136
   160                137 to 138
   150                139       
   144                140 to 141
   135                142       
   128                143       
   120                144 to 145
   108                146       
   100                147       
    96                148       
    90                149       
    80                150       
    72                151 to 152
    64                153       
    60                154       
    54                155       
    45                156       
    40                157       
    36                158       
    25                159       
    18                160       
 Number of points along a meridian.                 160
 Latitude of first grid point.                    89141
 Longitude of first grid point.                       0
 Latitude of last grid point.                    -89141
 Longitude of last grid point.                   358878
 Number of parallels between pole and equator.       80