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C $Id: diplat.f 3304 2011-01-17 15:25:59Z brideout $
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SUBROUTINE DIPLAT(TM,GDLAT,GLON,GDALT,AINC,DEC,RLATM)
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C .. Scalar Arguments ..
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DOUBLE PRECISION AINC,DEC,GDALT,GDLAT,GLON,RLATM,TM
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C ..
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C .. Local Scalars ..
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DOUBLE PRECISION B,BP,BR,BT,CP,CT,DTR,GCLAT,HB,P,PFX,PFY,PFZ,RFP,
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* RFR,RFT,RFX,RFY,RFZ,RKM,RP,RR,RT,SP,ST,T,XB,YB,ZB
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C ..
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C .. External Subroutines ..
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EXTERNAL CONVRT,GDV,MILMAG,VCTCNV
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C ..
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C .. Intrinsic Functions ..
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INTRINSIC ATAN,ATAN2,COS,SIN,SQRT,TAN
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C ..
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C .. Data statements ..
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C
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C DIPLAT CALCULATES THE INCLINATION, DECLINATION AND DIP LATITUDE
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C OF A POINT SPECIFIED BY ITS GEODETIC LATITUDE, LONGITUDE AND
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C ALTITUDE.
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C
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C INPUT
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C TM - TIME IN YEARS (E.G. 1975.2)
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C GDLAT - GEODETIC LATITUDE OF OBSERVATION POINT
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C GLON - LONGITUDE OF OBSERVATION POINT
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C GDALT - ALTITUDE ABOVE SPHEROID OF OBSERVATION POINT
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C OUTPUT
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C AINC - INCLINATION OF FIELD
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C DEC - DECLINATION OF FIELD
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C RLATM - DIP LATITUDE
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C
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DATA DTR/.0174532925199D0/
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C ..
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C
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C .....FIND GEOCENTRIC COORDINATES OF POINT.....
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CALL CONVRT(1,GDLAT,GDALT,GCLAT,RKM)
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C
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C .....CALCULATE MAGNETIC FIELD AT OBSERVATION POINT.....
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T = DTR*(90.D0-GCLAT)
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CT = COS(T)
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ST = SIN(T)
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P = DTR*GLON
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CP = COS(P)
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SP = SIN(P)
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CALL MILMAG(TM,RKM,ST,CT,SP,CP,BR,BT,BP,B)
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CALL GDV(GDLAT,GCLAT,BR,BT,BP,XB,YB,ZB)
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C
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C .....CALCULATE INCLINATION.....
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HB = SQRT(XB*XB+YB*YB)
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AINC = ATAN2(ZB,HB)/DTR
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C
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C .....CALCULATE DECLINATION.....
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DEC = ATAN2(YB,XB)/DTR
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C
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C .....CALCULATE DIP LATITUDE.....
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RLATM = ATAN(.5D0*TAN(DTR*AINC))/DTR
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CALL VCTCNV(RFX,RFY,RFZ,PFX,PFY,PFZ,RFR,RFT,RFP,RR,RT,RP,1)
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RETURN
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C
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END
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