WRF U/V 850mb inconsistent dimension sizes

[lslrsgis]

Dear WRF Community,

I am plotting 850mb U/V fields within wrfout files. However, it is found that U and V with different dimension sizes:
(1) U [bottom_top | 27] x [south_north | 267] x [west_east_stag | 271]
(2) V [bottom_top | 27] x [south_north_stag | 268] x [west_east | 270]

It is normal? Further, when trying to plot u850 and v850 in NCL through vector = wrf_vector(a,wks,u850,v850,opts). There is warning and failure as follows:

-----------------------------------------------------------------------------------------------------------------------------------------------------------
Variable: ull
Type: float
Total Size: 7814556 bytes
1953639 values
Number of Dimensions: 3
Dimensions and sizes: [bottom_top | 27] x [south_north | 267] x [west_east_stag | 271]
Coordinates:
Number Of Attributes: 6
FieldType : 104
MemoryOrder : XYZ
description : x-wind component
units : m s-1
stagger : X
coordinates : XLONG_U XLAT_U XTIME

Variable: vll
Type: float
Total Size: 7814880 bytes
1953720 values
Number of Dimensions: 3
Dimensions and sizes: [bottom_top | 27] x [south_north_stag | 268] x [west_east | 270]
Coordinates:
Number Of Attributes: 6
FieldType : 104
MemoryOrder : XYZ
description : y-wind component
units : m s-1
stagger : Y
coordinates : XLONG_V XLAT_V XTIME
(0) min=-13.6168 max=5.79369
(0) min=-1.51129 max=21.5164

Variable: u850
Type: float
Total Size: 289428 bytes
72357 values
Number of Dimensions: 2
Dimensions and sizes: [267] x [271]
Coordinates:
Number Of Attributes: 1
units : kts

Variable: v850
Type: float
Total Size: 289440 bytes
72360 values
Number of Dimensions: 2
Dimensions and sizes: [268] x [270]
Coordinates:
Number Of Attributes: 1
units : kts
fatal:VectorFieldInitialize: dimensions of vfUDataArray and vfVDataArray are inconsistent
fatal:Unable to initialize layer-Can't Create
fatal:Unable to access object with id:-4
fatal:Unable to access object with id:-4
warning:Unable to add DataItem "(null)" to DataList "vcVectorFieldData"
fatal:CompileDataListataList has no valid members

 

[Ming Chen]

This is what we expect, because WRF adopts the staggered grid structure. Please see more details at
http://www2.mmm.ucar.edu/wrf/users/docs/technote/v4_technote.pdf
(page 21)

 

[lslrsgis]

Thanks. That answers my question.