Layer-wise wind speed, wind direction data calculation problem.

[Jamil Anwar]

I have raw weather data in Grib format. I want to get layer-wise wind speed 
and wind-direction data but don't know how. I have "ctl" file 
named "hff00Z21jan2009.ctl" that I have to use along with many other Grib 
files. I am new to GrADS software and want help in this regard.

By q file I got following information related CTL file.

  Descriptor: C:/hff00Z21jan2009.ctl
  Binary: C:/hff00Z21jan2009_%f3
  Type = Gridded
  Xsize = 217  Ysize = 191  Zsize = 40  Tsize = 73
  Number of Variables = 43
    alhfl_s 0 121 ** surface latent heat flux [W/(m**2)]
    ashfl_s 0 122 ** surface sensible heat flux [W/(m**2)]
    asob_s 0 111 ** surface net short-wave radiation (surface) [W/(m**2)]
    asob_t 0 113 ** top of atmos net short-wave radiation (top of 
atmosphere) [W                                                             /(m**2)]
    athb_s 0 112 ** surface net long-wave radiation (surface) [W/(m**2)]
    athb_t 0 114 ** top of atmos net long-wave radiation (top of atmosphere) 
[W/                                                             (m**2)]
    aumfl_s 0 124 ** surface momentum flux, u component [N/(m**2)]
    avmfl_s 0 125 ** surface momentum flux, v component [N/(m**2)]
    clch 0 75 ** surface high cloud cover [%]
    clcl 0 73 ** surface low cloud cover [%]
    clcm 0 74 ** surface medium cloud cover [%]
    clct 0 71 ** surface total cloud cover [%]
    clct_mod 0 204 ** surface modified total cloud cover  (0..1) [1]
    cldepth 0 203 ** surface cloud depth (grey scale
    fis 0 6 ** surface geopotential [(m**2)/(s**2)]
    frland 0 81 ** surface land cover (1=land, 0=sea) [1]
    hbas_con 0 68 ** cloud base, convective clouds (above msl) [m]
    htop_con 0 69 ** cloud top, convective clouds (above msl) [m]
    htop_dc 0 82 ** surface top of dry convection (above msl) [m]
    hzerocl 0 84 ** height of 0 degree Celsius isotherm above msl [m]
    ps 0 1 ** surface pressure [Pa]
    qc 40 31 ** specific cloud water content, grid scale [kg/kg]
    qv_s 0 51 ** surface specific humidity [kg/kg]
    qv 40 51 ** specific humidity [kg/kg]
    rain_con 0 113 ** surface surface precipitation amount, rain, convective 
[kg                                                             /m**2]
    rain_gsp 0 102 ** surface surface precipitation amount, rain, grid scale 
[kg                                                             /m**2]
    snow_con 0 78 ** surface convective snow [kg/(m**2)]
    snow_gsp 0 79 ** surface large scale snow [kg/(m**2)]
    t_g 0 11 ** surface temperature [K]
    t_2m 0 11 ** 2 m temperature [K]
    t 40 11 ** temperature [K]
    td_2m 0 17 ** 2 m dew-point temperature [K]
    tmax_2m 0 15 ** 2 m maximum temperature [K]
    tmin_2m 0 16 ** 2 m minimum temperature [K]
    t_s 0 85 ** soil temperature [K]
    u_10m 0 33 ** 10 m u-component (zonal) of wind [m/s]
    u 40 33 ** u-component (zonal) of wind [m/s]
    v_10m 0 34 ** 10 m v-component (merdional) of wind [m/s]
    v 40 34 ** v-component (merdional) of wind [m/s]
    vmax_10m 0 187 ** 10 m maximum wind velocity [m/s]