da_earth_2_model_wind.inc

1 subroutine da_earth_2_model_wind(eu,ev,mu,mv,lon)
2 
3    !---------------------------------------------------------------------------
4    ! Purpose: Convert earth wind to model wind.
5    !
6    ! Need map projection parameters.
7    !
8    ! IPROJ: Projection type
9    ! PHIC:  Central latitude 
10    ! XLONC: Central longitude
11    ! XN:    Cone projection
12    ! CONV:  180/Pi
13    !---------------------------------------------------------------------------
14 
15    implicit none
16 
17    real, intent(in)  :: eu, ev
18    real, intent(out) :: mu, mv
19    real, intent(in)  :: lon
20 
21    real :: xlonrt, ang
22 
23    if (trace_use) call da_trace_entry("da_earth_2_model_wind")
24 
25    ! for mercator projection, the winds are as in earth coordinates
26 
27    if (map_projection == 3) then
28       mu = eu
29       mv = ev
30       return
31    end if
32 
33    ! for conversion to grid coordinates,
34    ! see program datamap, subr vect, and
35    ! ANTHES METEO. 597 NOTES, EQUA. 2.23, 2.25, 2.28.
36 
37    xlonrt = xlonc-lon
38 
39    if (xlonrt > 180.0) xlonrt=xlonrt-360.0
40    if (xlonrt <-180.0) xlonrt=xlonrt+360.0
41 
42    ang=xlonrt*cone_factor*pi/180.0
43 
44    if (phic < 0.0) ang=-ang
45 
46    mu = ev*sin(ang) + eu*cos(ang)
47    mv = ev*cos(ang) - eu*sin(ang)
48 
49    if (trace_use) call da_trace_exit("da_earth_2_model_wind")
50 
51 end subroutine da_earth_2_model_wind
52 
53