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Diffstat (limited to 'src/slalib/atmt.f')
| -rw-r--r-- | src/slalib/atmt.f | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/src/slalib/atmt.f b/src/slalib/atmt.f new file mode 100644 index 0000000..82d0ecd --- /dev/null +++ b/src/slalib/atmt.f @@ -0,0 +1,54 @@ + SUBROUTINE sla__ATMT (R0, T0, ALPHA, GAMM2, DELM2, + : C1, C2, C3, C4, C5, C6, R, T, DN, RDNDR) +*+ +* - - - - - +* A T M T +* - - - - - +* +* Internal routine used by REFRO +* +* Refractive index and derivative with respect to height for the +* troposphere. +* +* Given: +* R0 d height of observer from centre of the Earth (metre) +* T0 d temperature at the observer (deg K) +* ALPHA d alpha ) +* GAMM2 d gamma minus 2 ) see HMNAO paper +* DELM2 d delta minus 2 ) +* C1 d useful term ) +* C2 d useful term ) +* C3 d useful term ) see source +* C4 d useful term ) of sla_REFRO +* C5 d useful term ) +* C6 d useful term ) +* R d current distance from the centre of the Earth (metre) +* +* Returned: +* T d temperature at R (deg K) +* DN d refractive index at R +* RDNDR d R * rate the refractive index is changing at R +* +* Note that in the optical case C5 and C6 are zero. +* +* P.T.Wallace Starlink 30 May 1997 +* +* Copyright (C) 1997 Rutherford Appleton Laboratory +*- + + IMPLICIT NONE + + DOUBLE PRECISION R0,T0,ALPHA,GAMM2,DELM2,C1,C2,C3,C4,C5,C6, + : R,T,DN,RDNDR + + DOUBLE PRECISION TT0,TT0GM2,TT0DM2 + + + T = MAX(MIN(T0-ALPHA*(R-R0),320D0),100D0) + TT0 = T/T0 + TT0GM2 = TT0**GAMM2 + TT0DM2 = TT0**DELM2 + DN = 1D0+(C1*TT0GM2-(C2-C5/T)*TT0DM2)*TT0 + RDNDR = R*(-C3*TT0GM2+(C4-C6/TT0)*TT0DM2) + + END |