var/da/da_ssmi/da_spemiss_tl.inc

   1 subroutine da_spemiss_tl(f,tk,theta,ssw,ev,eh,TGL_tk,TGL_ev,TGL_eh                               )
   2
   3    !-----------------------------------------------------------------------
   4    ! Purpose: returns the specular emissivity of sea water for given
   5    ! freq. (GHz), temperature T (K), incidence angle theta (degrees),
   6    ! salinity (permil)
   7    !
   8    ! Returned values verified against data in Klein and Swift (1977) and
   9    ! against Table 3.8 in Olson (1987, Ph.D. Thesis)
  10    !
  11    ! Input  : TGL_tk
  12    ! Output : TGL_ev, TGL_eh, ev, eh
  13    !------------------------------------------------------------------------
  14
  15    implicit none
  16
  17    real, intent(in)    :: f, tk, theta, TGL_tk
  18    real, intent(inout) :: ssw
  19    real, intent(out)   :: TGL_ev, TGL_eh, ev, eh
  20
  21    real :: epsr,epsi,TGL_epsr,TGL_epsi
  22
  23    real    ::  tc,costh,sinth,rthet
  24    complex ::  etav,etah,eps,cterm1v,cterm1h,cterm2,cterm3v,cterm3h,epsnew
  25    complex ::  TGL_etav,TGL_eps,TGL_cterm1v,TGL_cterm2,TGL_cterm3v
  26    complex ::  TGL_cterm3h,TGL_epsnew
  27    ! complex   uniti
  28    real    ::  tmp1r,tmp1i,tmp2r,tmp2i
  29    ! real :: rnorm,tmp0i,tmp0r
  30    real    ::  TGL_tc,TGL_tmp1r
  31    ! real :: TGL_tmp0r,TGL_tmp0i,TGL_rnorm
  32    real    ::  TGL_tmp1i,TGL_tmp2r,TGL_tmp2i
  33
  34    if (trace_use) call da_trace_entry("da_spemiss_tl")
  35
  36
  37    tc          =      tk - t_kelvin
  38    TGL_tc      =  TGL_tk
  39
  40    call da_epsalt_tl(f,tc,ssw,epsr,epsi,TGL_tc, TGL_epsr, TGL_epsi )
  41
  42        eps     =  cmplx(epsr,epsi)
  43    TGL_eps     =  cmplx(TGL_epsr,TGL_epsi)
  44        etav    =  eps
  45    TGL_etav    =  TGL_eps
  46    etah        =  (1.0,0.0)
  47    rthet       =  theta*0.017453292
  48    costh       =  cos(rthet)
  49    sinth       =  sin(rthet)
  50    sinth       =  sinth*sinth
  51        cterm1v =  etav*costh
  52    TGL_cterm1v =  TGL_etav*costh
  53    cterm1h     =  etah*costh
  54        epsnew  =      eps - sinth
  55    TGL_epsnew  =  TGL_eps
  56    cterm2      =  csqrt(epsnew)
  57
  58    ! calculate TGL_cterm2
  59
  60    if (cabs(epsnew) .gt. 0.0) then
  61       TGL_cterm2      =  TGL_epsnew*0.5/cterm2
  62    else
  63       TGL_cterm2      =  0.0
  64    end if
  65
  66    ! Wei's Comment
  67    !     It is not a standard fortran if statement here.
  68
  69    !     if (0) then
  70    !               tmp0r   =  real(epsnew)
  71    !           TGL_tmp0r   =  real(TGL_epsnew)
  72    !               tmp0i   = -aimag(epsnew)
  73    !           TGL_tmp0i   = -aimag(TGL_epsnew)
  74    !               rnorm   =  sqrt(tmp0r*tmp0r+tmp0i*tmp0i)
  75    !               uniti   =  (0,1)
  76    !           if (rnorm .gt. 0.0) then
  77    !             if (abs(tmp0i) .gt. 0.0) then
  78    !                TGL_rnorm =  (tmp0r*TGL_tmp0r + tmp0i*TGL_tmp0i)/rnorm
  79    !                TGL_cterm2=  cterm2*0.5*(TGL_rnorm/rnorm  &
  80    !                                      -uniti*(TGL_tmp0r*rnorm-TGL_rnorm*tmp0r)/(rnorm*tmp0i))
  81    !             else
  82    !                TGL_rnorm =  TGL_tmp0r
  83    !                TGL_cterm2=  TGL_tmp0r*0.5/sqrt(tmp0r)
  84    !             end if
  85    !           else
  86    !             TGL_rnorm =  0.0
  87    !             TGL_cterm2=  0.0
  88    !           end if
  89    !     end if
  90
  91    ! End Wei's Comment
  92
  93        cterm3v =  (cterm1v - cterm2)/(cterm1v + cterm2)
  94    TGL_cterm3v =  (TGL_cterm1v - TGL_cterm2)/(cterm1v + cterm2) &
  95                  -cterm3v*(TGL_cterm1v + TGL_cterm2)/(cterm1v + cterm2)
  96        cterm3h =  (cterm1h - cterm2)/(cterm1h + cterm2)
  97    TGL_cterm3h = -TGL_cterm2/(cterm1h + cterm2) &
  98                  -cterm3h*TGL_cterm2/(cterm1h + cterm2)
  99        tmp1r   =  real(cterm3v)
 100    TGL_tmp1r   =  real(TGL_cterm3v)
 101        tmp1i   = -aimag(cterm3v)
 102    TGL_tmp1i   = -aimag(TGL_cterm3v)
 103    ! ev      =  1.0 - cabs(cterm3v)**2
 104        ev      =  1.0 - (tmp1r*tmp1r+tmp1i*tmp1i)
 105    TGL_ev      = -2.0*tmp1r*TGL_tmp1r - 2.0*tmp1i*TGL_tmp1i
 106
 107        tmp2r   =  real(cterm3h)
 108    TGL_tmp2r   =  real(TGL_cterm3h)
 109        tmp2i   = -aimag(cterm3h)
 110    TGL_tmp2i   = -aimag(TGL_cterm3h)
 111    ! eh      =  1.0 - cabs(cterm3h)**2
 112        eh      =  1.0 - (tmp2r*tmp2r+tmp2i*tmp2i)
 113    TGL_eh      = -2.0*tmp2r*TGL_tmp2r - 2.0*tmp2i*TGL_tmp2i
 114
 115    if (trace_use) call da_trace_exit("da_spemiss_tl")
 116
 117 end subroutine da_spemiss_tl
 118
 119