NCL计算wrfout文件的月均值问题

王佳钰

NCL初学者，我想用NCL计算WRF出来的文件中，温度的月平均值，
这是我写的ncl脚本：
a = addfile("wrfout_2016-01-15_18.nc","r")
P = a->P
Pb = a->PB
P = P + Pb
T = a->T
T = T + 300.
TK = wrf_tk (P, T)
TKAvg = dim_avg_n_Wrap(TK,0)
printVarSummary(TKAvg)
这是运行出来的东西：
Copyright (C) 1995-2019 - All Rights Reserved
University Corporation for Atmospheric Research
NCAR Command Language Version 6.6.2
The use of this software is governed by a License Agreement.
See http://www.ncl.ucar.edu/ for more details.

Variable: TKAvg
Type: float
Total Size: 5806080 bytes
            1451520 values
Number of Dimensions: 3
Dimensions and sizes:        [bottom_top | 32] x [south_north | 180] x [west_east | 252]
Coordinates:
Number Of Attributes: 3
  description :        Temperature
  units :        K
  average_op_ncl :        dim_avg_n over dimension(s): Time
请问我这个有错误吗？要怎么看这月平均值呢？
谢谢各位大神！！！