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slalib/atms.f

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+      SUBROUTINE sla__ATMS (RT, TT, DNT, GAMAL, R, DN, RDNDR)
+*+
+*     - - - - -
+*      A T M S
+*     - - - - -
+*
+*  Internal routine used by REFRO
+*
+*  Refractive index and derivative with respect to height for the
+*  stratosphere.
+*
+*  Given:
+*    RT      d    height of tropopause from centre of the Earth (metre)
+*    TT      d    temperature at the tropopause (K)
+*    DNT     d    refractive index at the tropopause
+*    GAMAL   d    constant of the atmospheric model = G*MD/R
+*    R       d    current distance from the centre of the Earth (metre)
+*
+*  Returned:
+*    DN      d    refractive index at R
+*    RDNDR   d    R * rate the refractive index is changing at R
+*
+*  Last revision:   26 December 2004
+*
+*  Copyright P.T.Wallace.  All rights reserved.
+*
+*  License:
+*    This program is free software; you can redistribute it and/or modify
+*    it under the terms of the GNU General Public License as published by
+*    the Free Software Foundation; either version 2 of the License, or
+*    (at your option) any later version.
+*
+*    This program is distributed in the hope that it will be useful,
+*    but WITHOUT ANY WARRANTY; without even the implied warranty of
+*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+*    GNU General Public License for more details.
+*
+*    You should have received a copy of the GNU General Public License
+*    along with this program (see SLA_CONDITIONS); if not, write to the 
+*    Free Software Foundation, Inc., 59 Temple Place, Suite 330, 
+*    Boston, MA  02111-1307  USA
+*
+*-
+
+      IMPLICIT NONE
+
+      DOUBLE PRECISION RT,TT,DNT,GAMAL,R,DN,RDNDR
+
+      DOUBLE PRECISION B,W
+
+
+      B = GAMAL/TT
+      W = (DNT-1D0)*EXP(-B*(R-RT))
+      DN = 1D0+W
+      RDNDR = -R*B*W
+
+      END