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72 lines
2.3 KiB
Fortran
72 lines
2.3 KiB
Fortran
SUBROUTINE sla__ATMT (R0, T0, ALPHA, GAMM2, DELM2,
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: C1, C2, C3, C4, C5, C6, R, T, DN, RDNDR)
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*+
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* - - - - -
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* A T M T
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* - - - - -
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*
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* Internal routine used by REFRO
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*
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* Refractive index and derivative with respect to height for the
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* troposphere.
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*
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* Given:
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* R0 d height of observer from centre of the Earth (metre)
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* T0 d temperature at the observer (K)
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* ALPHA d alpha )
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* GAMM2 d gamma minus 2 ) see HMNAO paper
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* DELM2 d delta minus 2 )
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* C1 d useful term )
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* C2 d useful term )
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* C3 d useful term ) see source
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* C4 d useful term ) of sla_REFRO
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* C5 d useful term )
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* C6 d useful term )
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* R d current distance from the centre of the Earth (metre)
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*
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* Returned:
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* T d temperature at R (K)
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* DN d refractive index at R
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* RDNDR d R * rate the refractive index is changing at R
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*
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* Note that in the optical case C5 and C6 are zero.
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*
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* Last revision: 26 December 2004
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*
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* Copyright P.T.Wallace. All rights reserved.
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*
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* License:
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (see SLA_CONDITIONS); if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA
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*
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*-
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IMPLICIT NONE
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DOUBLE PRECISION R0,T0,ALPHA,GAMM2,DELM2,C1,C2,C3,C4,C5,C6,
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: R,T,DN,RDNDR
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DOUBLE PRECISION TT0,TT0GM2,TT0DM2
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T = MAX(MIN(T0-ALPHA*(R-R0),320D0),100D0)
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TT0 = T/T0
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TT0GM2 = TT0**GAMM2
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TT0DM2 = TT0**DELM2
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DN = 1D0+(C1*TT0GM2-(C2-C5/T)*TT0DM2)*TT0
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RDNDR = R*(-C3*TT0GM2+(C4-C6/TT0)*TT0DM2)
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END
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