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Fix bug in plotting
Fix bug in plotting
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geo-cgm.f
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C =====================================================================
C Downloaded from ftp://nssdcftp.gsfc.nasa.gov/models
C /geomagnetic/geo_cgm/
C by B. Rideout on Dec. 26, 2002. A description of this
C code can be found
C at http://nssdc.gsfc.nasa.gov/space/cgm/cgm.html
C The following changes were made from imported version:
C
C 1. Main method commented out
C 2. Prior to successfully running remake_file:
C - Inline ! comments removed
C - DFLOAT -> DBLE
C 3. remake_file script (nag_apt + tcl) run
C 4. Saved all common blocks, Saved arrays in igrf,
C otherwise needed -fno-automatic flag for g77
C 5. Made the method GEOCGM01 return as soon as cgm lat and long done
C for speed purpose (otherwise, its very slow)
C
C PROGRAM GEO-CGM Version 2001 July 2001
C This version is significantly redesigned and now it consist of two
C major parts:
C
C 1. MAIN PROGRAM GEO-CGM which provides a dialog to key-entry the data
C
C 2. SUBROUTINE GEOCGM01 which does all necessary calculations
C
C The user can write a new main program and run GEOCGM01 independently
C RECENT UPDATES:
C Jul 12, 2001 Correction in IGRF-extrapolation should be cycled 1,66
C Jul 11, 2001 Corrected typo in IGRF-2000 G(2,0) coef.: it was -2167.
C Jun 29, 2001 Correction in "Write out the results into the file:"
C in IUH(n),IUM(n) - n = 1,2,3,4 in four lines
C Apr 11, 2001 GEOLOW is modified to account for interpolation of
C CGM meridians near equator across the 360/0 boundary
C Jan 22, 2001 The code was extended to 2000-2005 (IGRF and RECALC)
C Feb 8, 1999 The code was significantly modularized (v. 9.9)
C Jan 22, 1999 The function OVL_ANG is added (v.9.1)
C Jan 18, 1999 Main program is modified to call SUBR GEOCGM (v.9.0)
C Jan 15, 1999 "Geographic" is replaced by "Geocentric" and positive
C direction of the meridian_angle is corrected in the
C Southern Hemisphere
C Aug 26, 1997 IGRF is updated with IGRF-1995, SV 1995-2000, and
C GEOPACK-1996
C Dec 22, 1995 Output 132 characters and correction of BF=180-BF
C Aug 15, 1995 GEOPACK-1994 was incorporated in the version 7.4
C =====================================================================
C DIMENSION DAT(11,4),PLA(4),PLO(4),IUH(4),IUM(4)
C CHARACTER FOUT*20,FINP*20,HEAD*25,HST*5,HCJ*5
C CHARACTER YS*1,COD*3,DIV*42,DVV*15
C DATA DIV/'------------------------------------------'/
C DATA DVV/'---------------'/
C
C 100 FORMAT(
C *' '/
C *' ----------------------- GEO <--> CGM -------------------------'/
C *' | |'/
C *' | The GEO-CGM code provides transformation between CORRECTED |'/
C *' | GEOMAGNETIC (CGM) and geographic (GEOCENTRIC) coordinates |'/
C *' | of a given point utilizing the 1945-2000 DGRF/IGRF models. |'/
C *' | The B-min approach is applied to calculate CGM coordinates |'/
C *' | through the near-equator area where the definition of CGM |'/
C *' | coordinates is invalid. However, GEO<->GGM transformations |'/
C *' | are not performed at certain regions where the CGM equator |'/
C *' | cannot be defined at all (see Gustafsson et al. [1992] and |'/
C *' | http://nssdc.gsfc.nasa.gov/space/cgm/ for details). |'/
C *' | |'/
C *' |---AUTHORS: |'/
C *' | Natalia Papitashvili (WDC-B2, Moscow, now at NASA/NSSDC) & |'/
C *' | Vladimir Papitashvili (IZMIRAN, Moscow, now at SPRL, Univ. |'/
C *' | of Michigan) with contributions from Boris Belov & Volodya |'/
C *' | Popov (both at IZMIRAN) and from Therese Moretto (DMI,DSRI,|'/
C *' | now at NASA/GSFC). The original version of the code can be |'/
C *' | found in Tsyganenko et al. [1987]; the GEOPACK-96 software |'/
C *' | package is utilized here with minor modifications. |'/
C *' | |'/
C *' |---REFERENCES: |'/
C *' | Gustafsson, G., N. E. Papitashvili, and V. O. Papitashvili,|'/
C *' | A revised corrected geomagnetic coordinate system for |'/
C *' | Epochs 1985 and 1990, J. Atmos. Terr. Phys., 54, 1609, |'/
C *' | 1992. |'/
C *' | Tsyganenko, N. A., A. V. Usmanov, V. O. Papitashvili, N. E.|'/
C *' | Papitashvili, and V. A. Popov, Software for computations |'/
C *' | of geomagnetic field and related coordinate systems, SGC,|'/
C *' | Moscow, 58 pp., 1987. |'/
C *' |------------------------------------------------------------|'/
C *' | Main GEO-CGM.FOR & subroutine GEOCGM01.FOR July 2001 |'/
C *' --------------------------------------------------------------'/
C */' Type <M/m> if you need more information on input and output '/
C *' or hit <Enter> to proceed further')
C WRITE (*,100)
C READ (*,'(A1)') YS
C IF (YS.eq.'M'.or.YS.eq.'m') WRITE (*,110)
C 110 FORMAT(
C *' '/
C *' --------------------------------------------------------------'/
C *' | INPUT: |'/
C *' | - Geocentric or Corrected GeoMagnetic Latitude / Longitude |'/
C *' | - Altitude above 1-Re (6371.2 km) surface: 40,000 km limit |'/
C *' | - Year for the DGRF/IGRF model epochs from 1945 to 2005 |'/
C *' | |'/
C *' | OUTPUT: |'/
C *' | - GEOCENTRIC, CGM, and AACGM coordinates of a given point |'/
C *' | (see http://superdarn.jhuapl.edu/aacgm/ for definition |'/
C *' | of the Altitude Adjusted CGM coordinates) |'/
C *' | - DGRF/IGRF magnetic field components at this point |'/
C *' | - Geocentric and CGM coordinates of the magnetically |'/
C *' | conjugate point and the magnetic field line footprint |'/
C *' | - Apex of the magnetic field line (in Re) |'/
C *' | - MLT midnight in UT (hr:mm) at the given point |'/
C *' | - Meridian_angle: the azimuth along a great-circle arc to |'/
C *' | the North (South) CGM pole measured from the geographic |'/
C *' | North (South) meridian; positive to East (West) |'/
C *' | - Oval_angle: the angle between local tangents to the CGM |'/
C *' | and geographic (geocentric) latitudes; this angle is |'/
C *' | presented as the azimuth to the local "magnetic north" |'/
C *' | ("magnetic south") if the eastward (westward) tangent |'/
C *' | to the CGM latitude points southward (northward) from |'/
C *' | local East (West); measured positive to East (West) |'/
C *' --------------------------------------------------------------'/
C *)
C IRD is an index to key-enter the input parameters or read the file
C IRD = 0
C WRITE (*,*)
C * 'Enter <Y/y> to read the file or <Enter> for keyboard:'
C READ (*,'(A1)') YS
C IF (YS.eq.'Y'.or.YS.eq.'y') THEN
C IRD = 1
C WRITE (*,*) 'Sample of the input data file (A3,2F7.2,F8.1)'
C WRITE (*,*) '(everything below this line, including header)'
C WRITE (*,*) 'COD Lat. Long. H, km'
C WRITE (*,*) 'MOS 56.34 276.89 0.'
C WRITE (*,*) 'SAT 1.23 150.00 36600.5'
C WRITE (*,*) 'VOS -78.46 106.83 3.2'
C WRITE (*,*)
C 11 WRITE (*,*) 'Enter input_file name:'
C READ (*,'(A20)/') FINP
C OPEN(11,FILE=FINP,STATUS='OLD',IOSTAT=IOS)
C if(IOS.NE.0) then
C write(*,*) 'File ',FINP,' does not exist!'
C goto 11
C endif
C READ(11,'(A25)') HEAD
C
C 12 WRITE (*,*)'Enter name of the output file to write results'
C READ (*,'(A20)') FOUT
C OPEN(12,FILE=FOUT,STATUS='NEW',IOSTAT=IOS)
C if(IOS.NE.0) then
C write(*,*) 'File ',FOUT,' already exists!'
C goto 12
C endif
C ENDIF
C
C Read the input data from a keyboard
C
C 15 WRITE (*,*) 'Enter year <1945 to 2005> (enter 0 to quit)'
C WRITE (*,*) ' or / to use previous value'
C WRITE (*,*) '****'
C READ (*,*) iyear
C if (iyear.lt.1) goto 111
C if (iyear.lt.1945.or.iyear.gt.2005) then
C write (*,*) '*** WARNING: Year is out of range! ***'
C goto 15
C endif
C WRITE (*,*)'Enter 1 to compute GEO --> CGM'
C WRITE (*,*)' or -1 to compute GEO <-- CGM'
C WRITE (*,*)' or / to use previous value'
C READ (*,*) ICOR
C IF(IRD.EQ.1) WRITE (12,250) IYEAR,DVV,DIV,DIV
C 20 CONTINUE
C Nullify the parameter array before getting to the next point
C DO I = 1,11
C DO J = 1,4
C DAT(I,J) = 0.
C ENDDO
C ENDDO
C IF(IRD.EQ.1) THEN
C Read data from file
C IF (ICOR.EQ. 1) THEN
C READ(11,240,END=111) COD,SLAR,SLOR,HI
C DAT(1,1) = SLAR
C DAT(2,1) = SLOR
C ELSE
C READ(11,240,END=111) COD,CLAR,CLOR,HI
C DAT(3,1) = CLAR
C DAT(4,1) = CLOR
C ENDIF
C GOTO 50
C ELSE
C 30 WRITE(*,*)'Enter North/South Latitude and East/West Longitude'
C WRITE(*,*)'<76.54 -123.48> or <-76.54 123.48>'
C WRITE(*,*)'or enter / to use previous values'
C IF (ICOR.EQ. 1) THEN
C READ (*,*) SLAR,SLOR
C DAT(1,1) = SLAR
C DAT(2,1) = SLOR
C ELSE
C READ (*,*) CLAR,CLOR
C DAT(3,1) = CLAR
C DAT(4,1) = CLOR
C ENDIF
C 40 WRITE (*,*)'Enter altitude above 1-Re (6371.2 km) surface'
C WRITE (*,*)'<0 to 40,000> km (or / to use previous value)'
C READ (*,*) HI
C IF(HI.GT.40000.) THEN
C WRITE(*,*) 'Altitude is too high...'
C GOTO 40
C ENDIF
C WRITE (*,*)
C ENDIF
C 50 CONTINUE
C Call the subroutine GEOCGM01 where DAT - 11 input/output parameters
C (slar,slor,clar,clor,rbm,btr,bfr,brr,ovl,azm,utm) for the start point
C (*,1), for the conjugate point (*,2), and then for their footprints
C at 1-Re surface - (*,3) and (*,4), respectively
C CALL GEOCGM01(ICOR,IYEAR,HI,DAT,PLA,PLO)
C Headers for the CGM pole coordinates
C if(DAT(3,1).lt.0.) then
C HST = 'South'
C else
C HST = 'North'
C endif
C if(DAT(3,2).lt.0.) then
C HCJ = 'South'
C else
C HCJ = 'North'
C endif
C Convert UT to HHH:MM for the start and conjugate points
C CALL UTHM(DAT(11,1),IUH(1),IUM(1))
C CALL UTHM(DAT(11,2),IUH(2),IUM(2))
C Convert UT to HHH:MM for footprints of the start and conj points
C IF(HI.GT.0.) THEN
C CALL UTHM(DAT(11,3),IUH(3),IUM(3))
C CALL UTHM(DAT(11,4),IUH(4),IUM(4))
C ENDIF
C IF (IRD.EQ.1) THEN
C Write out the results into the file
C WRITE (*,'(A1,A3,A17)') ' ',COD,' is processing...'
C WRITE (12,260) COD,HI,(DAT(i,1),i=1,10),IUH(1),IUM(1)
C IF(HI.GT.0.) THEN
C WRITE (12,265) 0.,(DAT(i,3),i=1,10),IUH(3),IUM(3)
C WRITE (12,270) 0.,(DAT(i,4),i=1,10),IUH(4),IUM(4)
C ENDIF
C WRITE (12,280) HI,(DAT(i,2),i=1,10),IUH(2),IUM(2)
C Go to get a new point
C GOTO 20
C ELSE
C Write out the results on the display
C WRITE (*,*)
C Write parameters of the CGM pole(s) for the start point
C WRITE (*,130) DIV,DIV
C WRITE (*,140) IYEAR,HST,HI,PLA(1),PLO(1)
C IF(HI.GT.0.) WRITE (*,145) 0.,PLA(3),PLO(3)
C WRITE (*,130) DIV,DIV
C Write parameters for the start point
C WRITE (*,150) DIV,DIV,HI
C WRITE (*,155) (DAT(i,1),i=1,10),IUH(1),IUM(1)
C Write parameters for the footprints
C IF(HI.GT.0.) THEN
C WRITE (*,160)
C WRITE (*,155) (DAT(i,3),i=1,10),IUH(3),IUM(3)
C WRITE (*,170)
C WRITE (*,155) (DAT(i,4),i=1,10),IUH(4),IUM(4)
C ENDIF
C Write parameters of the CGM pole(s) for the conj point
C WRITE (*,180) HI
C WRITE (*,155) (DAT(i,2),i=1,10),IUH(2),IUM(2)
C WRITE (*,*)
C Write parameters of the CGM pole(s) for the conj point
C WRITE (*,130) DIV,DIV
C WRITE (*,140) IYEAR,HCJ,HI,PLA(2),PLO(2)
C IF(HI.GT.0.) WRITE (*,145) 0.,PLA(4),PLO(4)
C WRITE (*,130) DIV,DIV
C WRITE (*,*)
C Go to get a new point
C GOTO 15
C Ending to write data
C ENDIF
C 130 FORMAT(2X,2A42)
C 140 FORMAT(' Year: ',I4,4X,A5,' CGM pole at ',F7.1,
C +' km: Lat.=',F7.2,' Long.=',F7.2)
C 145 FORMAT(' at ',F7.1,
C +' km: ',F7.2,' ',F7.2)
C 150 FORMAT(
C +' Geocentric CGM L-value IGRF Magnetic Field',
C +' Oval & Azimuth MLTMN'/
C +' Lat. Long. Lat. Long. Re H,nT D,deg Z,nT',
C +' angles N/S:+E/W in UT'/2X,2A42//' Starting point at ',
C +F7.1,' km:'/)
C 155 FORMAT(4F8.2,F7.2,F8.0,F8.2,F8.0,2F8.2,2X,I2,':',I2)
C 160 FORMAT(/2X,
C +'Footprint at 1-Re & AACGM coords of the starting point:'/)
C 170 FORMAT(/2X,
C +'Footprint at 1-Re & AACGM coords of the conjugate point:'/)
C 180 FORMAT(/2X,'Conjugate point at ',F7.1,' km:'/)
C 240 FORMAT(A3,2F7.2,F8.1)
C 250 FORMAT(' Year Altitude Geocentric CGM L-value ',
C +'IGRF Magnetic Field Oval & Azimuth MLTMN'/
C +I5,' (km) Lat. Long. Lat. Long. Re H,nT ',
C +'D,deg Z,nT angles N/S:+E/W in UT'/A15,2A42)
C 260 FORMAT(/
C + 1X,A3,1X,F8.1,4F8.2,F7.2,F8.0,F8.2,F8.0,2F8.2,2X,I2,':',I2)
C 265 FORMAT(' FTP',F8.1,4F8.2,F7.2,F8.0,F8.2,F8.0,2F8.2,2X,I2,':',I2)
C 270 FORMAT(' CFT',F8.1,4F8.2,F7.2,F8.0,F8.2,F8.0,2F8.2,2X,I2,':',I2)
C 280 FORMAT(' CONJ',F8.1,4F8.2,F7.2,F8.0,F8.2,F8.0,2F8.2,2X,I2,':',I2)
C 111 STOP
C END
C *********************************************************************
SUBROUTINE UTHM(UTM,IUH,IUM)
C Converts UTM from the hour and fraction to HH:MM
C .. Scalar Arguments ..
DOUBLE PRECISION UTM
INTEGER IUH,IUM
C ..
C .. Intrinsic Functions ..
INTRINSIC INT,NINT
C ..
IUH = INT(UTM)
IF (IUH.EQ.99) THEN
IUM = 99
ELSE
IUM = NINT((UTM-IUH)*60)
END IF
RETURN
END
C *********************************************************************
C =====================================================================
SUBROUTINE GEOCGM01(ICOR,IYEAR,HI,DAT,PLA,PLO)
C Version 2001 for GEO-CGM.FOR April 2001
C Apr 11, 2001 GEOLOW is modified to account for interpolation of
C CGM meridians near equator across the 360/0 boundary
C AUTHORS:
C Natalia E. Papitashvili (WDC-B2, Moscow, Russia, now at NSSDC,
C NASA/Goddard Space Flight Center, Greenbelt, Maryland)
C Vladimir O. Papitashvili (IZMIRAN, Moscow, Russia, now at SPRL,
C The University of Michigan, Ann Arbor)
C Conributions from Boris A. Belov and Vladimir A. Popov (both at
C IZMIRAN), as well as from Therese Moretto (DMI, DSRI, now at
C NASA/GSFC).
C The original version of this code is described in the brochure by
C N.A. Tsyganenko, A.V. Usmanov, V.O. Papitashvili, N.E. Papitashvili,
C and V.A. Popov, Software for computations of geomagnetic field and
C related coordinate systems, Soviet Geophys. Committ., Moscow, 58 pp.,
C 1987. A number of subroutines from the revised GEOPACK-96 software
C package developed by Nikolai A. Tsyganenko and Mauricio Peredo are
C utilized in this code with some modifications (see full version of
C GEOPACK-96 on http://www-spof.gsfc.nasa.gov/Modeling/geopack.html).
C This code consists of the main subroutine GEOCGM99, five functions
C (OVL_ANG, CGMGLA, CGMGLO, DFRIDR, and AZM_ANG), eigth new and revised
C subroutines from the above-mentioned brochure (MLTUT, MFC, FTPRNT,
C GEOLOW, CORGEO, GEOCOR, SHAG, and RIGHT), and 9 subroutines from
C GEOPACK-96 (IGRF, SPHCAR, BSPCAR, GEOMAG, MAGSM, SMGSM, RECALC, SUN)
C =====================================================================
C Input parameters:
C icor = +1 geo to cgm
C -1 cgm to geo
C iyr = year
C hi = altitude
C slar = geocentric latitude
C slor = geocentric longitude (east +)
C These two pairs can be either input or output parameters
C clar = cgm latitude
C clor = cgm longitude (east +)
C Output parameters:
C Array DAT(11,4) consists of 11 parameters (slar, slor, clar, clor,
C rbm, btr, bfr, brr, ovl, azm, utm) organized for the start point
C (*,1), its conjugate point (*,2), then for the footprints at 1-Re
C of the start (*,3) and conjugate (*,4) points
C Description of parameters used in the subroutine:
C slac = conjugate geocentric latitude
C sloc = conjugate geocentric longitude
C slaf = footprint geocentric latitude
C slof = footprint geocentric longitude
C rbm = apex of the magnetic field line in Re (Re=6371.2 km)
C (this parameter approximately equals the McIlwain L-value)
C btr = IGRF Magnetic field H (nT)
C bfr = IGRF Magnetic field D (deg)
C brr = IGRF Magnetic field Z (nT)
C ovl = oval_angle as the azimuth to "magnetic north":
C + east in Northern Hemisphere
C + west in Southern Hemisphere
C azm = meridian_angle as the azimuth to the CGM pole:
C + east in Northern Hemisphere
C + west in Southern Hemisphere
C utm = magnetic local time (MLT) midnight in UT hours
C pla = array of geocentric latitude and
C plo = array of geocentric longitudes for the CGM poles
C in the Northern and Southern hemispheres at a given
C altitude (indices 1 and 2) and then at the Earth's
C surface - 1-Re or zero altitude - (indices 3 and 4)
C dla = dipole latitude
C dlo = dipole longitude
C =====================================================================
C Year (for example, as for Epoch 1995.0 - no fraction of the year)
C .. Scalar Arguments ..
DOUBLE PRECISION HI
INTEGER ICOR,IYEAR
C ..
C .. Array Arguments ..
DOUBLE PRECISION DAT(11,4),PLA(4),PLO(4)
C ..
C .. Local Scalars ..
DOUBLE PRECISION ACLAC,ACLAR,ACLOC,ACLOR,AZM,BFR,BRR,BTR,CLAC,
* CLAJ,CLAR,CLOC,CLOJ,CLOR,DAA,DLA,DLO,DOO,OVL,
* PLAJ,PLAN,PLAN1,PLAS,PLAS1,PLOJ,PLON,PLON1,PLOS,
* PLOS1,PMC,PMM,PMP,PMR,RBM,RE,RJ,SLAC,SLACF,SLAJ,
* SLAL,SLAR,SLARF,SLOC,SLOCF,SLOJ,SLOL,SLOR,SLORF,
* UT
INTEGER I,ICOUNT,J
C CHARACTER*12 STR
C ..
C .. External Functions ..
DOUBLE PRECISION AZM_ANG,OVL_ANG
EXTERNAL AZM_ANG,OVL_ANG
C ..
C .. External Subroutines ..
EXTERNAL CORGEO,FTPRNT,GEOCOR,GEOLOW,MFC,MLTUT
C ..
C .. Intrinsic Functions ..
INTRINSIC ABS
C ..
C .. Common blocks ..
COMMON /C1/AA,II,BB
COMMON /IYR/IYR
COMMON /NM/NM
COMMON /RZ/RH
DOUBLE PRECISION RH
INTEGER IYR,NM
DOUBLE PRECISION AA(27),BB(8)
INTEGER II(2)
SAVE /C1/,/IYR/,/NM/,/RZ/
C ..
IYR = IYEAR
C Earth's radius (km)
RE = 6371.2D0
C NM is the number of harmonics
NM = 10
C The radius of the sphere to compute the coordinates (in Re)
RH = (RE+HI)/RE
C Correction of latitudes and longitudes if they are entered beyond of
C the limits (this actually does not affect coordinate calculations
C but the oval/meridian angles and MLT midnight cannot be computed)
IF (DAT(1,1).GT.90.D0) DAT(1,1) = 180.D0 - DAT(1,1)
IF (DAT(1,1).LT.-90.D0) DAT(1,1) = -180.D0 - DAT(1,1)
IF (DAT(3,1).GT.90.D0) DAT(3,1) = 180.D0 - DAT(3,1)
IF (DAT(3,1).LT.-90.D0) DAT(3,1) = -180.D0 - DAT(3,1)
IF (DAT(2,1).GT.360.D0) DAT(2,1) = DAT(2,1) - 360.D0
IF (DAT(2,1).LT.-360.D0) DAT(2,1) = DAT(2,1) + 360.D0
IF (DAT(4,1).GT.360.D0) DAT(4,1) = DAT(4,1) - 360.D0
IF (DAT(4,1).LT.-360.D0) DAT(4,1) = DAT(4,1) + 360.D0
C Computation of CGM coordinates from geocentric ones at high- and
C middle latitudes
IF (ICOR.EQ.1) THEN
SLAR = DAT(1,1)
SLOR = DAT(2,1)
IF (ABS(SLAR).EQ.90.D0) SLOR = 360.D0
CALL GEOCOR(SLAR,SLOR,RH,DLA,DLO,CLAR,CLOR,PMR)
DAT(3,1) = CLAR
DAT(4,1) = CLOR
ELSE
C Computation of geocentric coordinates from CGM ones at high- and
C middle latitudes
CLAR = DAT(3,1)
CLOR = DAT(4,1)
IF (ABS(CLAR).EQ.90.D0) CLOR = 360.D0
CALL CORGEO(SLAR,SLOR,RH,DLA,DLO,CLAR,CLOR,PMR)
DAT(1,1) = SLAR
DAT(2,1) = SLOR
END IF
C PMI is L-shell parameter for the magnetic field line; limit to 16 Re
IF (PMR.GE.16.D0) PMR = 999.99D0
DAT(5,1) = PMR
C Check if CGM_Lat has been calculated, then go for the conjugate point
IF (CLAR.GT.999.D0) THEN
C CGM_Lat has NOT been calculated, call GEOLOW for computation of the
C CGM coordinates at low latitudes using the CBM approach (see the
C reference in GEOLOW)
CALL GEOLOW(SLAR,SLOR,RH,CLAR,CLOR,RBM,SLAC,SLOC)
DAT(3,1) = CLAR
DAT(4,1) = CLOR
IF (RBM.GE.16.D0) RBM = 999.99D0
DAT(5,1) = RBM
C Conjugate point coordinates at low latitudes
C these two lines seems to mess me up - change by brideout
C WRITE (STR,FMT='(2F6.2)') SLAC,SLOC
C READ (STR,FMT='(2F6.2)') SLAC,SLOC
C DAT(1,2) = SLAC
C DAT(2,2) = SLOC
C CALL GEOCOR(SLAC,SLOC,RH,DAA,DOO,CLAC,CLOC,RBM)
C IF (CLAC.GT.999.D0) CALL GEOLOW(SLAC,SLOC,RH,CLAC,CLOC,RBM,
C * SLAL,SLOL)
C DAT(3,2) = CLAC
C DAT(4,2) = CLOC
C DAT(5,2) = RBM
C ELSE
C Computation of the magnetically conjugated point at high- and
C middle latitudes
C CLAC = -CLAR
C CLOC = CLOR
C DAT(3,2) = CLAC
C DAT(4,2) = CLOC
C CALL CORGEO(SLAC,SLOC,RH,DAA,DOO,CLAC,CLOC,PMC)
C DAT(1,2) = SLAC
C DAT(2,2) = SLOC
C IF (PMC.GE.16.D0) PMC = 999.99D0
C DAT(5,2) = PMC
END IF
C Same RBM for footprints as for the starting and conjugate points
C
C For the present we only need cgm lat and cgm long - for speed, return here
C IF (1.EQ.1) THEN
C RETURN
C END IF
DAT(5,3) = DAT(5,1)
DAT(5,4) = DAT(5,2)
C Calculation of the magnetic field line footprint at the
C Earth's surface for the starting point
IF (RH.GT.1.D0 .AND. CLAR.LT.999.D0 .AND. CLAR.LT.999.D0) THEN
CALL FTPRNT(RH,SLAR,SLOR,CLAR,CLOR,ACLAR,ACLOR,SLARF,SLORF,
* 1.D0)
DAT(1,3) = SLARF
DAT(2,3) = SLORF
DAT(3,3) = ACLAR
DAT(4,3) = ACLOR
C and for the conjugate point
CALL FTPRNT(RH,SLAC,SLOC,CLAC,CLOC,ACLAC,ACLOC,SLACF,SLOCF,
* 1.D0)
DAT(1,4) = SLACF
DAT(2,4) = SLOCF
DAT(3,4) = ACLAC
DAT(4,4) = ACLOC
ELSE
DO I = 1,4
DO J = 3,4
DAT(I,J) = 999.99D0
END DO
END DO
END IF
C Computation of geocentric coordinates of the North or South CGM
C poles for a given year at the altitude RH and Earth's surface (1-Re)
CALL CORGEO(PLAN,PLON,RH,DAA,DOO,90.D0,360.D0,PMP)
PLAN1 = PLAN
PLON1 = PLON
CALL CORGEO(PLAS,PLOS,RH,DAA,DOO,-90.D0,360.D0,PMP)
PLAS1 = PLAS
PLOS1 = PLOS
IF (RH.GT.1.D0) THEN
CALL CORGEO(PLAN1,PLON1,1.D0,DAA,DOO,90.D0,360.D0,PMP)
CALL CORGEO(PLAS1,PLOS1,1.D0,DAA,DOO,-90.D0,360.D0,PMM)
END IF
IF (CLAR.LT.0.D0) THEN
PLA(1) = PLAS
PLO(1) = PLOS
ELSE
PLA(1) = PLAN
PLO(1) = PLON
END IF
IF (ACLAR.LT.0.D0) THEN
PLA(3) = PLAS1
PLO(3) = PLOS1
ELSE
PLA(3) = PLAN1
PLO(3) = PLON1
END IF
IF (CLAC.LT.0.D0) THEN
PLA(2) = PLAS
PLO(2) = PLOS
ELSE
PLA(2) = PLAN
PLO(2) = PLON
END IF
IF (ACLAC.LT.0.D0) THEN
PLA(4) = PLAS1
PLO(4) = PLOS1
ELSE
PLA(4) = PLAN1
PLO(4) = PLON1
END IF
DO J = 1,4
DAT(6,J) = 99999.D0
DAT(7,J) = 999.99D0
DAT(8,J) = 99999.D0
DAT(9,J) = 999.99D0
DAT(10,J) = 999.99D0
DAT(11,J) = 99.99D0
END DO
ICOUNT = 2
IF (RH.GT.1.D0) ICOUNT = 4
RJ = RH
DO J = 1,1
IF (J.GT.2) RJ = 1.D0
PLAJ = PLA(J)
PLOJ = PLO(J)
SLAJ = DAT(1,J)
SLOJ = DAT(2,J)
CLAJ = DAT(3,J)
CLOJ = DAT(4,J)
C Computation of the IGRF components
C CALL MFC(SLAJ,SLOJ,RJ,BTR,BFR,BRR)
C DAT(6,J) = BTR
C DAT(7,J) = BFR
C DAT(8,J) = BRR
C Computation of the oval_angle (OVL) between the tangents to
C geographic and CGM latitudes at a given point (the code is slightly
C modified from the source provided by Therese Morreto in 1994). Note
C that rotation of OVL on 90 deg anticlockwise provides the azimuth
C to the local "magnetic" north (south) measured from the local
C geographic meridian. The OVL_ANG can be calculated only at middle
C and high latitudes where CGM --> GEO is permitted.
C OVL = OVL_ANG(SLAJ,SLOJ,CLAJ,CLOJ,RJ)
C DAT(9,J) = OVL
C Computation of the meridian_angle (AZM) between the geographic
C meridian and direction (azimuth along the great-circle arc) to
C the North (South) CGM pole
C AZM = AZM_ANG(SLAJ,SLOJ,CLAJ,PLAJ,PLOJ)
C DAT(10,J) = AZM
C Computation of the MLT midnight (in UT)
CALL MLTUT(SLAJ,SLOJ,CLAJ,PLAJ,PLOJ,UT)
DAT(11,J) = UT
C End of loop j = 1,icount
END DO
RETURN
END
C *********************************************************************
DOUBLE PRECISION FUNCTION OVL_ANG(SLA,SLO,CLA,CLO,RR)
C This function returns an estimate at the given location of the angle
C (oval_angle) between the directions (tangents) along the constant
C CGM and geographic latitudes by utilizing the function DFRIDR from
C Numerical Recipes for FORTRAN.
C This angle can be taken as the azimuth to the local "magnetic" north
C (south) if the eastward (westward) tangent to the local CGM latitude
C points south (north) from the local geographic latitude.
C Written by Therese Moretto in August 1994 (revised by V. Papitashvili
C in January 1999).
C Ignore points which nearly coincide with the geographic or CGM poles
C within 0.01 degree in latitudes; this also takes care if SLA or CLA
C are dummy values (e.g., 999.99)
C .. Scalar Arguments ..
DOUBLE PRECISION CLA,CLO,RR,SLA,SLO
C ..
C .. Local Scalars ..
DOUBLE PRECISION DENOM,ERR1,ERR2,HOM,STEP
C ..
C .. External Functions ..
DOUBLE PRECISION CGMGLA,CGMGLO,DFRIDR
EXTERNAL CGMGLA,CGMGLO,DFRIDR
C ..
C .. Intrinsic Functions ..
INTRINSIC ABS,DATAN2,DCOS
C ..
C .. Common blocks ..
COMMON /CGMGEO/CLAT,CR360,CR0,RH
DOUBLE PRECISION CLAT,RH
LOGICAL CR0,CR360
SAVE /CGMGEO/
C ..
IF (ABS(SLA).GE.89.99D0 .OR. ABS(CLA).GE.89.99D0 .OR.
* ABS(SLA).LT.30.D0) THEN
OVL_ANG = 999.99D0
RETURN
END IF
C Initialize values for the cgmglo and cgmgla functions
RH = RR
CLAT = CLA
CR360 = .false.
CR0 = .false.
C Judge if SLO may be crossing the 360-0 limit. If geocentric
C longitude of the location is larger than 270 deg, then cr360 is
C set "true"; if it is less than 90 deg, then cr0 is set "true".
IF (SLO.GE.270.D0) CR360 = .true.
IF (SLO.LE.90.D0) CR0 = .true.
C An initial stepsize (in degrees)
STEP = 10.D0
C Note that in the near-pole region the functions CGMGLA and CGMGLO
C could be called from DFRIDR with the CGM latitudes exceeded 90 or
C -90 degrees (e.g., 98 or -98) when STEP is added or subtracted to a
C given CGM latitude (CLA). This does not produce discontinuities in
C the functions because GEOCOR calculates GEOLAT smoothly for the
C points lying behind the pole (e.g., as for 82 or - 82 deg. in the
C above-mentioned example). However, it could be discontinuity in
C GEOLON if |GEOLAT| = 90 deg. - see CGMGLO for details.
HOM = DFRIDR(CGMGLA,CLO,STEP,ERR1)
DENOM = DFRIDR(CGMGLO,CLO,STEP,ERR2)
DENOM = DENOM*COS(SLA*0.017453293D0)
OVL_ANG = -ATAN2(HOM,DENOM)
OVL_ANG = OVL_ANG*57.2957751D0
RETURN
END
C *********************************************************************
DOUBLE PRECISION FUNCTION CGMGLA(CLON)
C This function returns the geocentric latitude as a function of CGM
C longitude with the CGM latitude held in common block CGMGEO.
C Essentially this function just calls the subroutine CORGEO.
C .. Scalar Arguments ..
DOUBLE PRECISION CLON
C ..
C .. Local Scalars ..
DOUBLE PRECISION DLA,DLO,GEOLAT,GEOLON,PMI,RR
C ..
C .. External Subroutines ..
EXTERNAL CORGEO
C ..
C .. Common blocks ..
COMMON /CGMGEO/CCLAT,CR360,CR0,RH
DOUBLE PRECISION CCLAT,RH
LOGICAL CR0,CR360
SAVE /CGMGEO/
C ..
RR = RH
IF (CLON.GT.360.D0) CLON = CLON - 360.D0
IF (CLON.LT.0.D0) CLON = CLON + 360.D0
CALL CORGEO(GEOLAT,GEOLON,RR,DLA,DLO,CCLAT,CLON,PMI)
CGMGLA = GEOLAT
RETURN
END
C *********************************************************************
DOUBLE PRECISION FUNCTION CGMGLO(CLON)
C Same as the function CGMGLA but this returns the geocentric
C longitude. If cr360 is true, geolon+360 deg is returned when geolon
C is less than 90 deg. If cr0 is true, geolon-360 deg is returned
C when geolon is larger than 270 degrees.
C .. Scalar Arguments ..
DOUBLE PRECISION CLON
C ..
C .. Local Scalars ..
DOUBLE PRECISION DLA,DLO,GEOLAT,GEOLON,PMI,RR
C ..
C .. External Subroutines ..
EXTERNAL CORGEO
C ..
C .. Intrinsic Functions ..
INTRINSIC ABS
C ..
C .. Common blocks ..
COMMON /CGMGEO/CCLAT,CR360,CR0,RH
DOUBLE PRECISION CCLAT,RH
LOGICAL CR0,CR360
SAVE /CGMGEO/
C ..
RR = RH
IF (CLON.GT.360.D0) CLON = CLON - 360.D0
IF (CLON.LT.0.D0) CLON = CLON + 360.D0
10 CONTINUE
CALL CORGEO(GEOLAT,GEOLON,RR,DLA,DLO,CCLAT,CLON,PMI)
C Geographic longitude geolon could be any number (e.g., discontinued)
C when geolat is the geographic pole
IF (ABS(GEOLAT).GE.89.99D0) THEN
CLON = CLON - 0.01D0
GO TO 10
END IF
IF (CR360 .AND. (GEOLON.LE.90.D0)) THEN
CGMGLO = GEOLON + 360.D0
ELSE
IF (CR0 .AND. (GEOLON.GE.270.D0)) THEN
CGMGLO = GEOLON - 360.D0
ELSE
CGMGLO = GEOLON
END IF
END IF
RETURN
END
DOUBLE PRECISION
C **********************************************************************
* FUNCTION DFRIDR(FUNC,X,H,ERR)
C Numerical Recipes Fortran 77 Version 2.07
C Copyright (c) 1986-1995 by Numerical Recipes Software
C .. Parameters ..
DOUBLE PRECISION CON,CON2,BIG
INTEGER NTAB
DOUBLE PRECISION SAFE
PARAMETER (CON=1.4D0,CON2=CON*CON,BIG=1.D30,NTAB=10,SAFE=2.D0)
C ..
C .. Scalar Arguments ..
DOUBLE PRECISION ERR,H,X
C ..
C .. Function Arguments ..
DOUBLE PRECISION FUNC
EXTERNAL FUNC
C ..
C .. Local Scalars ..
DOUBLE PRECISION ERRT,FAC,HH
INTEGER I,J
C ..
C .. Local Arrays ..
DOUBLE PRECISION A(NTAB,NTAB)
C ..
C .. Intrinsic Functions ..
INTRINSIC ABS,MAX
C ..
DFRIDR = 0.0D0
HH = H
A(1,1) = (FUNC(X+HH)-FUNC(X-HH))/(2.0D0*HH)
ERR = BIG
DO 20 I = 2,NTAB
HH = HH/CON
A(1,I) = (FUNC(X+HH)-FUNC(X-HH))/(2.0D0*HH)
FAC = CON2
DO 10 J = 2,I
A(J,I) = (A(J-1,I)*FAC-A(J-1,I-1))/(FAC-1.D0)
FAC = CON2*FAC
ERRT = MAX(ABS(A(J,I)-A(J-1,I)),ABS(A(J,I)-A(J-1,I-1)))
IF (ERRT.LE.ERR) THEN
ERR = ERRT
DFRIDR = A(J,I)
END IF
10 CONTINUE
IF (ABS(A(I,I)-A(I-1,I-1)).GE.SAFE*ERR) RETURN
20 CONTINUE
RETURN
END
C *********************************************************************
DOUBLE PRECISION FUNCTION AZM_ANG(SLA,SLO,CLA,PLA,PLO)
C Computation of an angle between the north geographic meridian and
C direction to the North (South) CGM pole: positive azimuth is
C measured East (West) from geographic meridian, i.e., the angle is
C measured between the great-circle arc directions to the geographic
C and CGM poles. In this case the geomagnetic field components in
C XYZ (NEV) system can be converted into the CGM system in both
C hemispheres as:
C XM = X COS(alf) + Y SIN(alf)
C YM =-X SIN(alf) + Y COS(alf)
C Written by V. O. Papitashvili in mid-1980s; revised in February 1999
C Ignore points which nearly coincide with the geographic or CGM poles
C within 0.01 degree in latitudes; this also takes care if SLA or CLA
C are dummy values (e.g., 999.99)
C .. Scalar Arguments ..
DOUBLE PRECISION CLA,PLA,PLO,SLA,SLO
C ..
C .. Local Scalars ..
DOUBLE PRECISION ALFA,AM,BET,CM,RAD,SB,SP,SS,ST
C ..
C .. Intrinsic Functions ..
INTRINSIC ABS,DATAN2,DCOS,SIGN,DSIN,TAN
C ..
IF (ABS(SLA).GE.89.99D0 .OR. ABS(CLA).GE.89.99D0) THEN
AZM_ANG = 999.99D0
RETURN
END IF
SP = 1.D0
SS = 1.D0
C IF (SIGN(SP,PLA).NE.SIGN(SS,CLA)) THEN
C WRITE (*,FMT=9000) PLA,CLA
C 9000 FORMAT (/,'WARNING - The CGM pole PLA = ',f6.2,
C * ' and station CLAT = ',f6.2,
C * ' are not in the same hemisphere: AZM_ANG is incorrect!'
C * )
C END IF
RAD = 0.017453293D0
AM = (90.D0-ABS(PLA))*RAD
IF (SIGN(SP,PLA).EQ.SIGN(SS,SLA)) THEN
CM = (90.D0-ABS(SLA))*RAD
ELSE
CM = (90.D0+ABS(SLA))*RAD
END IF
IF (SLA.GE.0.D0) THEN
BET = (PLO-SLO)*RAD
ELSE
BET = (SLO-PLO)*RAD
END IF
SB = SIN(BET)
ST = SIN(CM)/TAN(AM) - COS(CM)*COS(BET)
ALFA = ATAN2(SB,ST)
AZM_ANG = ALFA/RAD
RETURN
END
C *********************************************************************
SUBROUTINE MLTUT(SLA,SLO,CLA,PLA,PLO,UT)
C Calculates the MLT midnight in UT hours
C Definition of the MLT midnight (MLTMN) here is different from the
C approach described elsewhere. This definition does not take into
C account the geomagnetic meridian of the subsolar point which causes
C seasonal variations of the MLTMN in UT time. The latter approach is
C perfectly applicable to the dipole or eccentric dipole magnetic
C coordinates but it fails with the CGM coordinates because there are
C forbidden areas near the geomagnetic equator where CGM coordinates
C cannot be calculated by definition [e.g., Gustafsson et al., JATP,
C 54, 1609, 1992].
C In this code the MLT midnight is defined as location of a given point
C on (or above) the Earth's surface strictly behind the North (South)
C CGM pole in such the Sun, the pole, and the point are lined up.
C This approach was originally proposed and coded by Boris Belov
C sometime in the beginning of 1980s; here it is slightly edited by
C Vladimir Papitashvili in February 1999.
C Ignore points which nearly coincide with the geographic or CGM poles
C within 0.01 degree in latitudes; this also takes care if SLA or CLA
C are dummy values (e.g., 999.99)
C .. Scalar Arguments ..
DOUBLE PRECISION CLA,PLA,PLO,SLA,SLO,UT
C ..
C .. Local Scalars ..
DOUBLE PRECISION A,BP,BT,CFF,CFT,QQ,QQU,QT,QTU,RAD,SP,SS,TPI,X,Y
C ..
C .. Intrinsic Functions ..
INTRINSIC ABS,DATAN2,DCOS,SIGN,DSIN
C ..
IF (ABS(SLA).GE.89.99D0 .OR. ABS(CLA).GE.89.99D0) THEN
UT = 99.99D0
RETURN
END IF
TPI = 6.283185307D0
RAD = 0.017453293D0
SP = 1.D0
SS = 1.D0
C IF (SIGN(SP,PLA).NE.SIGN(SS,CLA)) THEN
C WRITE (*,FMT=9000) PLA,CLA
C 9000 FORMAT (/,'WARNING - The CGM pole PLA = ',f6.2,
C * ' and station CLAT = ',f6.2,
C * ' are not in the same hemisphere: MLTMN is incorrect!')
C END IF
C Solve the spherical triangle
QQ = PLO*RAD
CFF = 90.D0 - ABS(PLA)
CFF = CFF*RAD
IF (CFF.LT.0.0000001D0) CFF = 0.0000001D0
IF (SIGN(SP,PLA).EQ.SIGN(SS,SLA)) THEN
CFT = 90.D0 - ABS(SLA)
ELSE
CFT = 90.D0 + ABS(SLA)
END IF
CFT = CFT*RAD
IF (CFT.LT.0.0000001D0) CFT = 0.0000001D0
QT = SLO*RAD
A = SIN(CFF)/SIN(CFT)
Y = A*SIN(QQ) - SIN(QT)
X = COS(QT) - A*COS(QQ)
UT = ATAN2(Y,X)
IF (UT.LT.0.D0) UT = UT + TPI
QQU = QQ + UT
QTU = QT + UT
BP = SIN(CFF)*COS(QQU)
BT = SIN(CFT)*COS(QTU)
UT = UT/RAD
UT = UT/15.D0
IF (BP.LT.BT) GO TO 10
IF (UT.LT.12.D0) UT = UT + 12.D0
IF (UT.GT.12.D0) UT = UT - 12.D0
10 CONTINUE
RETURN
END
C *********************************************************************
SUBROUTINE MFC(SLA,SLO,R,H,D,Z)
C Computation of the IGRF magnetic field components
C Extracted as a subroutine from the earlier version of GEO-CGM.FOR
C V. Papitashvili, February 1999
C This takes care if SLA or CLA are dummy values (e.g., 999.99)
C .. Scalar Arguments ..
DOUBLE PRECISION D,H,R,SLA,SLO,Z
C ..
C .. Local Scalars ..
DOUBLE PRECISION BF,BR,BT,F,RLA,RLO,X,Y
INTEGER I
C ..
C .. External Subroutines ..
EXTERNAL IGRF
C ..
C .. Intrinsic Functions ..
INTRINSIC DATAN2,SQRT
C ..
C .. Common blocks ..
COMMON /IYR/IYR
COMMON /NM/NM
INTEGER IYR,NM
SAVE /IYR/,/NM/
C ..
IF (SLA.GE.999.D0) THEN
X = 99999.D0
Y = 99999.D0
Z = 99999.D0
H = 99999.D0
D = 999.99D0
I = 999.99D0
F = 99999.D0
RETURN
END IF
C Computation of all geomagnetic field components
RLA = (90.D0-SLA)*0.017453293D0
RLO = SLO*0.017453293D0
CALL IGRF(IYR,NM,R,RLA,RLO,BR,BT,BF)
X = -BT
Y = BF
Z = -BR
H = SQRT(X**2+Y**2)
D = 57.2957751D0*ATAN2(Y,X)
I = 57.2957751D0*ATAN2(Z,H)
F = SQRT(H**2+Z**2)
RETURN
END
C *********************************************************************
SUBROUTINE FTPRNT(RH,SLA,SLO,CLA,CLO,ACLA,ACLO,SLAF,SLOF,RF)
C Calculation of the magnetic field line footprint at the Earth's
C (or any higher) surface.
C Extracted as a subroutine from the earlier version of GEO-CGM.FOR by
C V. Papitashvili in February 1999 but then the subroutine was revised
C to obtain the Altitude Adjusted CGM coordinates. The AACGM approach
C is proposed by Kile Baker of the JHU/APL, see their World Wide Web
C site http://sd-www.jhuapl.edu/RADAR/AACGM/ for details.
C If RF = 1-Re (i.e., at the Earth's surface), then the footprint
C location is defined as the Altitude Adjusted (AA) CGM coordinates
C for a given point (ACLA, ACLO).
C If RF = 1.xx Re (i.e., at any altitude above or below the starting
C point), then the conjunction between these two points can be found
C along the field line.
C This takes care if SLA or CLA are dummy values (e.g., 999.99)
C .. Scalar Arguments ..
DOUBLE PRECISION ACLA,ACLO,CLA,CLO,RF,RH,SLA,SLAF,SLO,SLOF
C ..
C .. Local Scalars ..
DOUBLE PRECISION ACOL,COL,DLAF,DLOF,DR0,DR1,DR10,DS,FRAC,PMIF,R,
* RF1,RL,RR,RSLA,RSLO,SN2,XF,XF1,YF,YF1,ZF,ZF1
C ..
C .. External Subroutines ..
EXTERNAL CORGEO,SHAG,SPHCAR
C ..
C .. Intrinsic Functions ..
INTRINSIC ABS,DASIN,DSIN,SQRT
C ..
C .. Common blocks ..
COMMON /IYR/IYR
COMMON /NM/NM
INTEGER IYR,NM
SAVE /IYR/,/NM/
C ..
IF (SLA.GT.999.D0 .OR. CLA.GT.999 .OR. RF.EQ.RH) THEN
ACLA = 999.99D0
ACLO = 999.99D0
SLAF = 999.99D0
SLOF = 999.99D0
RETURN
END IF
C Defining the Altitude Adjusted CGM coordinates for a given point
COL = (90.D0-CLA)*0.017453293D0
SN2 = (SIN(COL))**2
ACOL = ASIN(SQRT((SN2*RF)/RH))
ACLA = 90.D0 - ACOL*57.29577951D0
IF (CLA.LT.0.D0) ACLA = -ACLA
ACLO = CLO
CALL CORGEO(SLAF,SLOF,RF,DLAF,DLOF,ACLA,ACLO,PMIF)
IF (SLAF.LT.999.D0) RETURN
C Tracing the magnetic field line down to the Earth's surface at low
C latitudes if CORGEO failed to calculate geocentric coordinates SLAF
C and SLOF
IF (SN2.LT.0.0000001D0) SN2 = 0.0000001D0
RL = RH/SN2
FRAC = 0.03D0/(1.D0+3.D0/(RL-0.6D0))
C Checking direction of the magnetic field-line, so the step along
C the field-line will go down, to the Earth surface
IF (CLA.GE.0.D0) FRAC = -FRAC
DS = RH*FRAC
10 CONTINUE
C Start from an initial point
R = RH
RSLA = (90.D0-SLA)*0.0174533D0
RSLO = SLO*0.0174533D0
CALL SPHCAR(R,RSLA,RSLO,XF,YF,ZF,1)
RF1 = R
XF1 = XF
YF1 = YF
ZF1 = ZF
20 CALL SHAG(XF,YF,ZF,DS)
RR = SQRT(XF**2+YF**2+ZF**2)
IF (RR.GT.RH) THEN
DS = -DS
XF = XF1
YF = YF1
ZF = ZF1
GO TO 10
END IF
IF (RR.GT.RF) THEN
RF1 = RR
XF1 = XF
YF1 = YF
ZF1 = ZF
GO TO 20
ELSE
DR1 = ABS(RF1-RF)
DR0 = ABS(RF-RR)
DR10 = DR1 + DR0
IF (DR10.NE.0.D0) THEN
DS = DS*(DR1/DR10)
CALL SHAG(XF1,YF1,ZF1,DS)
END IF
CALL SPHCAR(RR,SLAF,SLOF,XF1,YF1,ZF1,-1)
SLAF = 90.D0 - SLAF*57.29578D0
SLOF = SLOF*57.29578D0
END IF
RETURN
END
C *********************************************************************
SUBROUTINE GEOLOW(SLAR,SLOR,RH,CLAR,CLOR,RBM,SLAC,SLOC)
C Calculates CGM coordinates from geocentric ones at low latitudes
C where the DGRF/IGRF magnetic field lines may never cross the dipole
C equatorial plane and, therefore, the definition of CGM coordinates
C becomes invalid.
C The code is written by Natalia and Vladimir Papitashvili as a part
C of the earlier versions of GEO-CGM.FOR; extracted as a subroutine by
C V. Papitashvili in February 1999.
C Apr 11, 2001 GEOLOW is modified to account for interpolation of
C CGM meridians near equator across the 360/0 boundary
C See the paper by Gustafsson, G., N. E. Papitashvili, and V. O.
C Papitashvili, A revised corrected geomagnetic coordinate system for
C Epochs 1985 and 1990 [J. Atmos. Terr. Phys., 54, 1609-1631, 1992]
C for detailed description of the B-min approach utilized here.
C This takes care if SLA is a dummy value (e.g., 999.99)
C .. Scalar Arguments ..
DOUBLE PRECISION CLAR,CLOR,RBM,RH,SLAC,SLAR,SLOC,SLOR
C ..
C .. Local Scalars ..
DOUBLE PRECISION B2,B3,BB2,BB3,BF,BM,BR,BT,CLA,CLO,COL,DAA,DD,
* DELAT,DELCLA,DELCLO,DELON,DHH,DOO,DR0,DR1,DR10,
* DS,DSD,DSLA,FRAC,PMM,R1,RBM1,RDEL,RL,RLA,RLAN,
* RLAS,RLO,RM,RNLAT,RNLON,RR,RSLAT,RSLON,SLA,SLAN,
* SLAS,SLL,SLM,SLO,SZ,X1,XBM,XBM1,XGEO,Y1,YBM,YBM1,
* YGEO,Z1,ZBM,ZBM1,ZGEO
INTEGER I,IH,IHEM,J,JC,JCN,JCS,JDEL,JDN,JDS,L1,L2,N999,NDIR,NOBM
C ..
C .. Local Arrays ..
DOUBLE PRECISION ARLAT(181),ARLON(181),BC(2)
C ..
C .. External Subroutines ..
EXTERNAL GEOCOR,IGRF,SHAG,SPHCAR
C ..
C .. Intrinsic Functions ..
INTRINSIC ABS,INT,DSIN,SQRT
C .. Common blocks ..
COMMON /IYR/IYR
COMMON /NM/NM
INTEGER IYR,NM
SAVE /IYR/,/NM/
C initialize
R1=0.0D0
RLAN=0.0D0
RLAS=0.0D0
RNLAT=0.0D0
RNLON=0.0D0
RSLAT=0.0D0
RSLON=0.0D0
SLAN=0.0D0
SLAS=0.0D0
JCN=0
JCS=0
C ..
IF (SLAR.GT.999.D0) THEN
CLAR = 999.99D0
CLOR = 999.99D0
SLAC = 999.99D0
SLOC = 999.99D0
RBM = 999.99D0
RETURN
END IF
C HH is an error (nT) to determine B-min along the magnetic field line
DHH = 0.5D0
C Filling the work arrays of CGM latitudes and longitudes with 999.99
C Note that at certain geocentric longitudes in the very near-equator
C region no "geomagnetic equator" can be defined at all.
DO J = 61,121
ARLAT(J) = 999.99D0
ARLON(J) = 999.99D0
END DO
SLO = SLOR
NDIR = 0
C Finding the geomagnetic equator as a projection of the B-min point
C found for the field lines started from the last latitude in each
C hemisphere where the CGM coordinates were obtained from geocentric
C ones (GEO --> CGM). First the CGM coordinates are calculated in the
C Northern (NDIR=0) and then in the Southern hemispheres (NDIR=1)
10 IF (NDIR.EQ.0) THEN
C Program works from 30 deg. latitude down to the geographic equator
C in the Northern Hemisphere
DO JC = 61,91
SLA = 90.D0 - (JC-1)
CALL GEOCOR(SLA,SLO,RH,DAA,DOO,CLA,CLO,PMM)
IF (CLA.GT.999.D0) THEN
NDIR = 1
GO TO 10
END IF
ARLAT(JC) = CLA
ARLON(JC) = CLO
END DO
NDIR = 1
GO TO 10
ELSE
C Program works from -30 deg. latitude down to the geographic equator
C in the Southern Hemisphere
DO JC = 121,92,-1
SLA = 90.D0 - (JC-1)
CALL GEOCOR(SLA,SLO,RH,DAA,DOO,CLA,CLO,PMM)
IF (CLA.GT.999.D0) THEN
NDIR = 0
GO TO 20
END IF
ARLAT(JC) = CLA
ARLON(JC) = CLO
END DO
NDIR = 0
END IF
20 CONTINUE
C Finding last geographic latitudes along SLO where CGM coordinates
C can be calculated
N999 = 0
NDIR = 0
DO JC = 61,121
IF (ARLAT(JC).GT.999.D0) THEN
IF (NDIR.EQ.0) THEN
JCN = JC - 1
RNLAT = ARLAT(JCN)
RNLON = ARLON(JCN)
NDIR = 1
N999 = 1
END IF
END IF
IF (ARLAT(JC).LT.999.D0) THEN
IF (NDIR.EQ.1) THEN
JCS = JC
RSLAT = ARLAT(JC)
RSLON = ARLON(JC)
NDIR = 0
GO TO 30
END IF
END IF
END DO
30 CONTINUE
C If there is no points with 999.99 found along the SLO meridian,
C then the IHEM loop will start from 3; otherwise it starts from 1
IF (N999.EQ.0) THEN
IH = 3
GO TO 40
ELSE
IH = 1
END IF
C Interpolation of the appropriate CGM longitudes between last
C geocentric latitudes along SLO where CGM coordinates were defined
C (modified by Freddy Christiansen of DMI to account for interpolation
C across the 360/0 boundary - April 11, 2001)
RDEL = JCS - JCN
IF (RDEL.EQ.0.D0) THEN
DELON = 0.D0
ELSE
IF (RSLON.GT.270.D0 .AND. RNLON.LT.90.D0) THEN
DELON = (RSLON-(RNLON+360.D0))/RDEL
ELSE
IF (RSLON.LT.90.D0 .AND. RNLON.GT.270.D0) THEN
DELON = (RSLON-(RNLON-360.D0))/RDEL
ELSE
DELON = (RSLON-RNLON)/RDEL
END IF
END IF
END IF
DO JC = JCN + 1,JCS - 1
ARLON(JC) = RNLON + DELON*(JC-JCN)
IF (ARLON(JC).LT.0.D0) ARLON(JC) = ARLON(JC) + 360.D0
END DO
40 CONTINUE
C Finding the CGM equator at SLO on the sphere with radius RH
NOBM = 0
DO IHEM = IH,3
RM = RH
C Defining the real equator point from the Northern Hemisphere
IF (IHEM.EQ.1) THEN
CLA = RNLAT
SLA = 90.D0 - (JCN-1.D0)
SLAN = SLA
END IF
C Defining the real equator point from the Southern Hemisphere
IF (IHEM.EQ.2) THEN
CLA = RSLAT
SLA = 90.D0 - (JCS-1)
SLAS = SLA
END IF
C Defining the apex of the current magnetic field line
IF (IHEM.EQ.3) THEN
CLA = 0.D0
SLA = SLAR
END IF
C Here CLA is used only to calculate FRAC
COL = (90.D0-CLA)*0.017453293D0
SLM = (90.D0-SLA)*0.017453293D0
SLL = SLO*0.017453293D0
CALL IGRF(IYR,NM,RM,SLM,SLL,BR,BT,BF)
SZ = -BR
CALL SPHCAR(RM,SLM,SLL,XGEO,YGEO,ZGEO,1)
BM = SQRT(BR*BR+BT*BT+BF*BF)
XBM = XGEO
YBM = YGEO
ZBM = ZGEO
RL = 1.D0/(SIN(COL))**2
FRAC = 0.03D0/(1.D0+3.D0/(RL-0.6D0))
IF (SZ.LE.0.D0) FRAC = -FRAC
DSD = RL*FRAC
DS = DSD
50 CONTINUE
C Keep two consequently computed points to define B-min
DO 80 I = 1,2
DD = DS
CALL SHAG(XGEO,YGEO,ZGEO,DD)
60 IF (I.NE.1) GO TO 70
XBM1 = XGEO
YBM1 = YGEO
ZBM1 = ZGEO
RBM1 = SQRT(XBM1**2+YBM1**2+ZBM1**2)
70 CONTINUE
CALL SPHCAR(RM,SLM,SLL,XGEO,YGEO,ZGEO,-1)
CALL IGRF(IYR,NM,RM,SLM,SLL,BR,BT,BF)
C Go and compute the conjugate point if no B-min was found at this
C magnetic field line (could happen at very near geomagnetic equator)
IF (RM.LT.RH) THEN
NOBM = 1
GO TO 140
END IF
BC(I) = SQRT(BR*BR+BT*BT+BF*BF)
80 CONTINUE
B2 = BC(1)
B3 = BC(2)
IF (BM.GT.B2 .AND. B2.LT.B3) GO TO 90
IF (BM.GE.B2 .AND. B2.LT.B3) GO TO 100
IF (BM.GT.B2 .AND. B2.LE.B3) GO TO 100
BM = BC(1)
XGEO = XBM1
YGEO = YBM1
ZGEO = ZBM1
XBM = XBM1
YBM = YBM1
ZBM = ZBM1
GO TO 50
90 BB3 = ABS(B3-B2)
BB2 = ABS(BM-B2)
IF (BB2.LT.DHH .AND. BB3.LT.DHH) GO TO 110
100 BM = BM
XGEO = XBM
YGEO = YBM
ZGEO = ZBM
DS = DS/2.D0
GO TO 50
110 CONTINUE
CALL SPHCAR(RBM1,RLA,RLO,XBM1,YBM1,ZBM1,-1)
RLA = 90.D0 - RLA*57.2957751D0
RLO = RLO*57.2957751D0
IF (IHEM.EQ.1) RLAN = RLA
IF (IHEM.EQ.2) RLAS = RLA
C Computation of the magnetically conjugate point at low latitudes
120 CONTINUE
IF (IHEM.EQ.3) THEN
RBM = RBM1
RM = RBM
DS = DSD
130 CONTINUE
CALL SHAG(XBM1,YBM1,ZBM1,DS)
RR = SQRT(XBM1**2+YBM1**2+ZBM1**2)
IF (RR.GT.RH) THEN
R1 = RR
X1 = XBM1
Y1 = YBM1
Z1 = ZBM1
GO TO 130
ELSE
DR1 = ABS(RH-R1)
DR0 = ABS(RH-RR)
DR10 = DR1 + DR0
IF (DR10.NE.0.D0) THEN
DS = DS*(DR1/DR10)
RM = R1
CALL SHAG(X1,Y1,Z1,DS)
END IF
CALL SPHCAR(RR,SLAC,SLOC,X1,Y1,Z1,-1)
SLAC = 90.D0 - SLAC*57.2957751D0
SLOC = SLOC*57.2957751D0
END IF
END IF
C End of loop IHEM
140 CONTINUE
END DO
IF (N999.EQ.0) GO TO 150
IF (NOBM.EQ.1) THEN
C Interpolation of CGM latitudes if there is no B-min at this
C magnetic field line
RDEL = JCS - JCN
IF (RDEL.EQ.0.D0) THEN
DELAT = 0.D0
ELSE
DELAT = (RSLAT-RNLAT)/RDEL
END IF
JDEL = 0
DO JC = JCN + 1,JCS - 1
JDEL = JDEL + 1
ARLAT(JC) = RNLAT + DELAT*JDEL
END DO
RBM = 999.99D0
SLAC = 999.99D0
SLOC = 999.99D0
ELSE
C Geocentric latitude of the CGM equator
RLA = (RLAN+RLAS)/2.D0
C Interpolation of the CGM latitudes in the Northern hemisphere
RDEL = SLAN - RLA
IF (RDEL.EQ.0.D0) THEN
DELAT = 0.D0
ELSE
DELAT = RNLAT/RDEL
END IF
JDN = ABS(RDEL)
JDEL = 0
DO JC = JCN + 1,JCN + JDN
JDEL = JDEL + 1
ARLAT(JC) = RNLAT - DELAT*JDEL
END DO
C Interpolation of the CGM latitudes in the Southern hemisphere
RDEL = SLAS - RLA
IF (RDEL.EQ.0.D0) THEN
DELAT = 0.D0
ELSE
DELAT = RSLAT/RDEL
END IF
JDS = ABS(RDEL)
JDEL = 0
DO JC = JCS - 1,JCS - JDS,-1
JDEL = JDEL + 1
ARLAT(JC) = RSLAT + DELAT*JDEL
END DO
END IF
150 CONTINUE
C Defining by interpolation the exact values of the CGM latitude
C and longitude between two adjacent values
L1 = 90.D0 - SLAR + 1.D0
IF (SLAR.LT.0.D0) THEN
L2 = L1 - 1
ELSE
L2 = L1 + 1
END IF
DSLA = ABS(SLAR-INT(SLAR))
DELCLA = ARLAT(L2) - ARLAT(L1)
DELCLO = ARLON(L2) - ARLON(L1)
CLAR = ARLAT(L1) + DELCLA*DSLA
CLOR = ARLON(L1) + DELCLO*DSLA
RETURN
END
C *********************************************************************
SUBROUTINE CORGEO(SLA,SLO,RH,DLA,DLO,CLA,CLO,PMI)
C Calculates geocentric coordinates from corrected geomagnetic ones.
C The code is written by Vladimir Popov and Vladimir Papitashvili
C in mid-1980s; revised by V. Papitashvili in February 1999
C This takes care if CLA is a dummy value (e.g., 999.99)
C .. Scalar Arguments ..
DOUBLE PRECISION CLA,CLO,DLA,DLO,PMI,RH,SLA,SLO
C ..
C .. Local Scalars ..
DOUBLE PRECISION AA10,CLAS,CLOS,COL,DLS,DR0,DR1,DR10,DS,FRAC,GTET,
* GTH,GXLA,PF,PMS,R,R0,R1,RBM,RFI,RL,RLO,RM,SAA,
* SAQ,SCLA,SLAC,SLOC,SN,SN2,TH,X,X1,XM,Y,Y1,YM,Z,
* Z1,ZM
INTEGER JC,NG
C ..
C .. External Subroutines ..
EXTERNAL GEOCOR,GEOLOW,GEOMAG,SHAG,SPHCAR
C ..
C .. Intrinsic Functions ..
INTRINSIC ABS,DATAN,DSIN,SQRT
C ..
C .. Common blocks ..
COMMON /IYR/IYR
COMMON /NM/NM
INTEGER IYR,NM
SAVE /IYR/,/NM/
C ..
JC = 0
IF (ABS(CLA).LT.1.D0) THEN
C WRITE (*,FMT=*)
C * 'WARNING - No calculations within +/-1 degree near CGM equator'
JC = 1
END IF
IF (CLA.GT.999.D0 .OR. JC.EQ.1) THEN
SLA = 999.99D0
SLO = 999.99D0
DLA = 999.99D0
DLO = 999.99D0
PMI = 999.99D0
RETURN
END IF
NG = NM
COL = 90.D0 - CLA
R = 10.D0
R1 = R
R0 = R
COL = COL*0.017453293D0
RLO = CLO*0.017453293D0
SN = SIN(COL)
SN2 = SN*SN
C The CGM latitude should be at least 0.01 deg. away of the CGM pole
IF (SN2.LT.0.000000003D0) SN2 = 0.000000003D0
C RFI = 1./SN2
RFI = RH/SN2
PMI = RFI
IF (PMI.GT.99.999D0) PMI = 999.99D0
AA10 = R/RFI
C RFI = R if COL = 90 deg.
IF (RFI.LE.R) GO TO 10
SAA = AA10/(1.D0-AA10)
SAQ = SQRT(SAA)
SCLA = ATAN(SAQ)
IF (CLA.LT.0) SCLA = 3.14159265359D0 - SCLA
GO TO 20
10 SCLA = 1.57079632679D0
R0 = RFI
20 CALL SPHCAR(R0,SCLA,RLO,XM,YM,ZM,1)
CALL GEOMAG(X,Y,Z,XM,YM,ZM,-1,IYR)
RL = R0
FRAC = -0.03D0/(1.D0+3.D0/(RL-0.6D0))
IF (CLA.LT.0.D0) FRAC = -FRAC
R = R0
30 DS = R*FRAC
NM = (1.D0+9.D0/R) + 0.5D0
CALL SHAG(X,Y,Z,DS)
R = SQRT(X**2+Y**2+Z**2)
IF (R.LE.RH) GO TO 40
R1 = R
X1 = X
Y1 = Y
Z1 = Z
GO TO 30
C Define intersection with the start surface
40 DR1 = ABS(RH-R1)
DR0 = ABS(RH-R)
DR10 = DR1 + DR0
IF (DR10.NE.0.D0) THEN
DS = DS*(DR1/DR10)
CALL SHAG(X1,Y1,Z1,DS)
END IF
CALL SPHCAR(R,GTET,GXLA,X1,Y1,Z1,-1)
GTH = GTET*57.2957751D0
SLO = GXLA*57.2957751D0
SLA = 90.D0 - GTH
CALL GEOMAG(X1,Y1,Z1,XM,YM,ZM,1,IYR)
CALL SPHCAR(RM,TH,PF,XM,YM,ZM,-1)
DLO = PF*57.2957751D0
DLA = 90.D0 - TH*57.2957751D0
NM = NG
C Because CORGEO cannot check if the CGM --> GEO transformation is
C performed correctly in the equatorial area (that is, where the IGRF
C field line may never cross the dipole equatorial plane). Therefore,
C the backward check is required for geocentric latitudes lower than
C 30 degrees (see the paper referenced in GEOLOW)
IF (ABS(SLA).LT.30.D0 .OR. ABS(CLA).LT.30.D0) THEN
CALL GEOCOR(SLA,SLO,RH,DLS,DLS,CLAS,CLOS,PMS)
IF (CLAS.GT.999.D0) CALL GEOLOW(SLA,SLO,RH,CLAS,CLOS,RBM,SLAC,
* SLOC)
IF (ABS(ABS(CLA)-ABS(CLAS)).GE.1.D0) THEN
C WRITE (*,FMT=*) 'WARNING - Selected CGM_Lat.=',CLA,
C * ' is located in the ',
C * 'near CGM equator area where the latter cannot be defined'
SLA = 999.99D0
SLO = 999.99D0
PMI = 999.99D0
END IF
END IF
RETURN
END
C *********************************************************************
SUBROUTINE GEOCOR(SLA,SLO,RH,DLA,DLO,CLA,CLO,PMI)
C Calculates corrected geomagnetic coordinates from geocentric ones
C The code is written by Vladimir Popov and Vladimir Papitashvili
C in mid-1980s; revised by V. Papitashvili in February 1999
C This takes care if SLA is a dummy value (e.g., 999.99)
C .. Scalar Arguments ..
DOUBLE PRECISION CLA,CLO,DLA,DLO,PMI,RH,SLA,SLO
C ..
C .. Local Scalars ..
DOUBLE PRECISION C,COL,DCL,DCO,DS,FRAC,GTET,GXLA,HHH,PF,R,R1,RL,
* RLO,RM,RRH,RZM,S,SN,SSLA,ST,SZM,TH,X,X1,XM,Y,Y1,
* YM,Z,Z1,ZM
INTEGER NG
C ..
C .. External Subroutines ..
EXTERNAL GEOMAG,SHAG,SPHCAR
C ..
C .. Intrinsic Functions ..
INTRINSIC ABS,DATAN,DSIN,SQRT
C ..
C .. Common blocks ..
COMMON /IYR/IYR
COMMON /NM/NM
INTEGER IYR,NM
SAVE /IYR/,/NM/
C ..
IF (SLA.GT.999.D0) THEN
CLA = 999.99D0
CLO = 999.99D0
DLA = 999.99D0
DLO = 999.99D0
PMI = 999.99D0
RETURN
END IF
NG = NM
COL = 90.D0 - SLA
R = RH
R1 = R
COL = COL*0.017453293D0
RLO = SLO*0.017453293D0
CALL SPHCAR(R,COL,RLO,X,Y,Z,1)
CALL GEOMAG(X,Y,Z,XM,YM,ZM,1,IYR)
CALL SPHCAR(RM,TH,PF,XM,YM,ZM,-1)
SZM = ZM
DLO = PF*57.2957751D0
DCO = TH*57.2957751D0
DLA = 90.D0 - DCO
RL = R/(SIN(TH))**2
FRAC = 0.03D0/(1.D0+3.D0/(RL-0.6D0))
IF (SZM.LT.0.D0) FRAC = -FRAC
C Error to determine the dipole equtorial plane: aprox. 0.5 arc min
HHH = 0.0001571D0
C Trace the IGRF magnetic field line to the dipole equatorial plane
10 DS = R*FRAC
20 NM = (1.D0+9.D0/R) + 0.5D0
R1 = R
X1 = X
Y1 = Y
Z1 = Z
CALL SHAG(X,Y,Z,DS)
CALL GEOMAG(X,Y,Z,XM,YM,ZM,1,IYR)
CALL SPHCAR(R,C,S,XM,YM,ZM,-1)
C As tracing goes above (RH+10_Re), use the dipole field line
IF (R.GT.10.D0+RH) GO TO 30
C If the field line returns to the start surface without crossing the
C dipole equatorial plane, no CGM coordinates can be calculated
IF (R.LE.RH) GO TO 40
DCL = C - 1.5707963268D0
IF (ABS(DCL).LE.HHH) GO TO 30
RZM = ZM
IF (SZM.GT.0.D0 .AND. RZM.GT.0.D0) GO TO 10
IF (SZM.LT.0.D0 .AND. RZM.LT.0.D0) GO TO 10
R = R1
X = X1
Y = Y1
Z = Z1
DS = DS/2.D0
GO TO 20
30 CALL GEOMAG(X,Y,Z,XM,YM,ZM,1,IYR)
CALL SPHCAR(R,GTET,GXLA,XM,YM,ZM,-1)
ST = ABS(SIN(GTET))
RRH = ABS(RH/(R-RH*ST**2))
CLA = 1.5707963D0 - ATAN(ST*SQRT(RRH))
CLA = CLA*57.2957751D0
CLO = GXLA*57.2957751D0
IF (SZM.LT.0.D0) CLA = -CLA
SSLA = 90.D0 - CLA
SSLA = SSLA*0.017453293D0
SN = SIN(SSLA)
C PMI = 1/(SN*SN)
PMI = RH/(SN*SN)
GO TO 50
40 CLA = 999.99D0
CLO = 999.99D0
PMI = 999.99D0
50 NM = NG
RETURN
END
C *********************************************************************
SUBROUTINE SHAG(X,Y,Z,DS)
C Similar to SUBR STEP from GEOPACK-1996 but SHAG takes into account
C only internal sources
C The code is re-written from Tsyganenko's subroutine STEP by
C Natalia and Vladimir Papitashvili in mid-1980s
C .. Scalar Arguments ..
DOUBLE PRECISION DS,X,Y,Z
C ..
C .. Local Scalars ..
DOUBLE PRECISION R11,R12,R13,R21,R22,R23,R31,R32,R33,R41,R42,R43,
* R51,R52,R53
C ..
C .. External Subroutines ..
EXTERNAL RIGHT
C ..
C .. Common blocks ..
COMMON /A5/DS3
DOUBLE PRECISION DS3
SAVE /A5/
C ..
DS3 = -DS/3.D0
CALL RIGHT(X,Y,Z,R11,R12,R13)
CALL RIGHT(X+R11,Y+R12,Z+R13,R21,R22,R23)
CALL RIGHT(X+.5D0*(R11+R21),Y+.5D0*(R12+R22),Z+.5D0*(R13+R23),R31,
* R32,R33)
CALL RIGHT(X+.375D0*(R11+3.D0*R31),Y+.375D0*(R12+3.D0*R32),
* Z+.375D0*(R13+3.D0*R33),R41,R42,R43)
CALL RIGHT(X+1.5D0*(R11-3.D0*R31+4.D0*R41),
* Y+1.5D0*(R12-3.D0*R32+4.D0*R42),
* Z+1.5D0*(R13-3.D0*R33+4.D0*R43),R51,R52,R53)
X = X + .5D0*(R11+4.D0*R41+R51)
Y = Y + .5D0*(R12+4.D0*R42+R52)
Z = Z + .5D0*(R13+4.D0*R43+R53)
RETURN
END
C *********************************************************************
SUBROUTINE RIGHT(X,Y,Z,R1,R2,R3)
C Similar to SUBR RHAND from GEOPACK-1996 but RIGHT takes into account
C only internal sources
C The code is re-written from Tsyganenko's subroutine RHAND
C by Natalia and Vladimir Papitashvili in mid-1980s
C .. Scalar Arguments ..
DOUBLE PRECISION R1,R2,R3,X,Y,Z
C ..
C .. Local Scalars ..
DOUBLE PRECISION B,BF,BR,BT,BX,BY,BZ,F,R,T
C ..
C .. External Subroutines ..
EXTERNAL BSPCAR,IGRF,SPHCAR
C ..
C .. Intrinsic Functions ..
INTRINSIC SQRT
C ..
C .. Common blocks ..
COMMON /A5/DS3
COMMON /IYR/IYR
COMMON /NM/NM
DOUBLE PRECISION DS3
INTEGER IYR,NM
SAVE /A5/,/IYR/,/NM/
C ..
CALL SPHCAR(R,T,F,X,Y,Z,-1)
CALL IGRF(IYR,NM,R,T,F,BR,BT,BF)
CALL BSPCAR(T,F,BR,BT,BF,BX,BY,BZ)
B = DS3/SQRT(BX**2+BY**2+BZ**2)
R1 = BX*B
R2 = BY*B
R3 = BZ*B
RETURN
END
C *********************************************************************
SUBROUTINE IGRF(IY,NM,R,T,F,BR,BT,BF)
C Modified by Bill Rideout to simply call igrf13syn from igrf13.f
C See igrf13.f for details
C
C ---INPUT PARAMETERS:
C IY - YEAR NUMBER (FROM 1945 UP TO 1990)
C NM - MAXIMAL ORDER OF HARMONICS TAKEN INTO ACCOUNT (NOT MORE THAN 10)
C R,T,F - SPHERICAL COORDINATES OF THE POINT (R IN UNITS RE=6371.2 KM,
C COLATITUDE T AND LONGITUDE F IN RADIANS)
C ---OUTPUT PARAMETERS:
C BR,BT,BF - SPHERICAL COMPONENTS OF MAIN GEOMAGNETIC FIELD (in nT)
C AUTHOR: NIKOLAI A. TSYGANENKO, INSTITUTE OF PHYSICS, ST.-PETERSBURG
C STATE UNIVERSITY, STARY PETERGOF 198904, ST.-PETERSBURG, RUSSIA
C (now the NASA Goddard Space Fligth Center, Greenbelt, Maryland)
IMPLICIT NONE
C G0, G1, and H1 are used in SUBROUTINE DIP to calculate geodipole's
C moment for a given year
C .. Scalar Arguments ..
DOUBLE PRECISION BF,BR,BT,B,F,R,T,FY
DOUBLE PRECISION RKM,LAT,LON
INTEGER IY,NM
C .. External Subroutines ..
external igrf13syn
C
FY = DBLE(IY)
RKM = R * 6371.2
LAT = T*57.295773
LON = F*57.295773
CALL igrf13syn(0,FY,2,RKM,LAT,LON,BT,BF,BR,B)
BR = BR * (-1.0D0)
BT = BT * (-1.0D0)
RETURN
END
C *********************************************************************
SUBROUTINE RECALC(IYR,IDAY,IHOUR,MIN,ISEC)
C THIS IS A MODIFIED VERSION OF THE SUBROUTINE RECOMP WRITTEN BY
C N. A. TSYGANENKO. SINCE I WANT TO USE IT IN PLACE OF SUBROUTINE
C RECALC, I HAVE RENAMED THIS ROUTINE RECALC AND ELIMINATED THE
C ORIGINAL RECALC FROM THIS VERSION OF THE <GEOPACK.FOR> PACKAGE.
C THIS WAY ALL ORIGINAL CALLS TO RECALC WILL CONTINUE TO WORK WITHOUT
C HAVING TO CHANGE THEM TO CALLS TO RECOMP.
C AN ALTERNATIVE VERSION OF THE SUBROUTINE RECALC FROM THE GEOPACK
C PACKAGE BASED ON A DIFFERENT APPROACH TO DERIVATION OF ROTATION
C MATRIX ELEMENTS
C THIS SUBROUTINE WORKS BY 20% FASTER THAN RECALC AND IS EASIER TO
C UNDERSTAND
C #####################################################
C # WRITTEN BY N.A. TSYGANENKO ON DECEMBER 1, 1991 #
C #####################################################
C Modified by Mauricio Peredo, Hughes STX at NASA/GSFC Code 695,
C September 1992
c Modified to accept years up to 2005 (V. Papitashvili, January 2001)
c Modified to accept dates up to year 2000 and updated IGRF coeficients
c from 1945 (updated by V. Papitashvili, February 1995)
C OTHER SUBROUTINES CALLED BY THIS ONE: SUN
C IYR = YEAR NUMBER (FOUR DIGITS)
C IDAY = DAY OF YEAR (DAY 1 = JAN 1)
C IHOUR = HOUR OF DAY (00 TO 23)
C MIN = MINUTE OF HOUR (00 TO 59)
C ISEC = SECONDS OF DAY(00 TO 59)
IMPLICIT NONE
C .. Scalar Arguments ..
INTEGER IDAY,IHOUR,ISEC,IYR,MIN
C ..
C .. Local Scalars ..
DOUBLE PRECISION CGST,DIP1,DIP2,DIP3,DJ,DT,DY1,DY2,DY3,DZ1,DZ2,
* DZ3,EXMAGX,EXMAGY,EXMAGZ,EYMAGX,EYMAGY,F1,F2,G10,
* G11,GST,H11,OBLIQ,S1,S2,S3,SDEC,SGST,SLONG,SQ,
* SQQ,SQR,SRASN,T,Y,Y1,Y2,Y3,Z1,Z2,Z3
INTEGER IDE,IPR,IYE
C ..
C .. External Subroutines ..
EXTERNAL SUN
C ..
C .. Intrinsic Functions ..
INTRINSIC DASIN,DATAN2,DCOS,DBLE,DSIN,SQRT
C ..
C .. Common blocks ..
COMMON /C1/ST0,CT0,SL0,CL0,CTCL,STCL,CTSL,STSL,SFI,CFI,SPS,CPS,
* SHI,CHI,HI,PSI,XMUT,A11,A21,A31,A12,A22,A32,A13,A23,A33,
* DS3,K,IY,BA
DOUBLE PRECISION A11,A12,A13,A21,A22,A23,A31,A32,A33,CFI,CHI,CL0,
* CPS,CT0,CTCL,CTSL,DS3,HI,PSI,SFI,SHI,SL0,SPS,ST0,
* STCL,STSL,XMUT
INTEGER IY,K
DOUBLE PRECISION BA(8)
SAVE /C1/
C ..
C .. Data statements ..
DATA IYE,IDE,IPR/3*0/
C ..
IF (IYR.EQ.IYE .AND. IDAY.EQ.IDE) GO TO 10
C IYE AND IDE ARE THE CURRENT VALUES OF YEAR AND DAY NUMBER
IY = IYR
IDE = IDAY
IF (IY.LT.1945) IY = 1945
IF (IY.GT.2005) IY = 2005
C WE ARE RESTRICTED BY THE INTERVAL 1945-2005, FOR WHICH THE IGRF
C COEFFICIENTS ARE KNOWN; IF IYR IS OUTSIDE THIS INTERVAL, THE
C SUBROUTINE GIVES A WARNING (BUT DOES NOT REPEAT IT AT THE NEXT CALLS)
C IF (IY.NE.IYR .AND. IPR.EQ.0) PRINT 9000,IYR,IY
IF (IY.NE.IYR) IPR = 1
IYE = IY
C LINEAR INTERPOLATION OF THE GEODIPOLE MOMENT COMPONENTS BETWEEN THE
C VALUES FOR THE NEAREST EPOCHS:
IF (IY.LT.1950) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1945.D0)/5.D0
F1 = 1.D0 - F2
G10 = 30594.D0*F1 + 30554.D0*F2
G11 = -2285.D0*F1 - 2250.D0*F2
H11 = 5810.D0*F1 + 5815.D0*F2
ELSE IF (IY.LT.1955) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1950.D0)/5.D0
F1 = 1.D0 - F2
G10 = 30554.D0*F1 + 30500.D0*F2
G11 = -2250.D0*F1 - 2215.D0*F2
H11 = 5815.D0*F1 + 5820.D0*F2
ELSE IF (IY.LT.1960) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1955.D0)/5.D0
F1 = 1.D0 - F2
G10 = 30500.D0*F1 + 30421.D0*F2
G11 = -2215.D0*F1 - 2169.D0*F2
H11 = 5820.D0*F1 + 5791.D0*F2
ELSE IF (IY.LT.1965) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1960.D0)/5.D0
F1 = 1.D0 - F2
G10 = 30421.D0*F1 + 30334.D0*F2
G11 = -2169.D0*F1 - 2119.D0*F2
H11 = 5791.D0*F1 + 5776.D0*F2
ELSE IF (IY.LT.1970) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1965.D0)/5.D0
F1 = 1.D0 - F2
G10 = 30334.D0*F1 + 30220.D0*F2
G11 = -2119.D0*F1 - 2068.D0*F2
H11 = 5776.D0*F1 + 5737.D0*F2
ELSE IF (IY.LT.1975) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1970.D0)/5.D0
F1 = 1.D0 - F2
G10 = 30220.D0*F1 + 30100.D0*F2
G11 = -2068.D0*F1 - 2013.D0*F2
H11 = 5737.D0*F1 + 5675.D0*F2
ELSE IF (IY.LT.1980) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1975.D0)/5.D0
F1 = 1.D0 - F2
G10 = 30100.D0*F1 + 29992.D0*F2
G11 = -2013.D0*F1 - 1956.D0*F2
H11 = 5675.D0*F1 + 5604.D0*F2
ELSE IF (IY.LT.1985) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1980.D0)/5.D0
F1 = 1.D0 - F2
G10 = 29992.D0*F1 + 29873.D0*F2
G11 = -1956.D0*F1 - 1905.D0*F2
H11 = 5604.D0*F1 + 5500.D0*F2
ELSE IF (IY.LT.1990) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1985.D0)/5.D0
F1 = 1.D0 - F2
G10 = 29873.D0*F1 + 29775.D0*F2
G11 = -1905.D0*F1 - 1848.D0*F2
H11 = 5500.D0*F1 + 5406.D0*F2
ELSE IF (IY.LT.1995) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1990.D0)/5.D0
F1 = 1.D0 - F2
G10 = 29775.D0*F1 + 29682.D0*F2
G11 = -1848.D0*F1 - 1789.D0*F2
H11 = 5406.D0*F1 + 5318.D0*F2
ELSE IF (IY.LT.2000) THEN
F2 = (DBLE(IY)+DBLE(IDAY)/365.D0-1995.D0)/5.D0
F1 = 1.D0 - F2
G10 = 29682.D0*F1 + 29615.D0*F2
G11 = -1789.D0*F1 - 1728.D0*F2
H11 = 5318.D0*F1 + 5186.D0*F2
ELSE
DT = DBLE(IY) + DBLE(IDAY)/365.D0 - 2000.D0
G10 = 29615.D0 - 14.6D0*DT
G11 = -1728.D0 + 10.7D0*DT
H11 = 5186.D0 - 22.5D0*DT
END IF
C NOW CALCULATE THE COMPONENTS OF THE UNIT VECTOR EzMAG IN GEO COORD
C SYSTEM:
C SIN(TETA0)*COS(LAMBDA0), SIN(TETA0)*SIN(LAMBDA0), AND COS(TETA0)
C ST0 * CL0 ST0 * SL0 CT0
SQ = G11**2 + H11**2
SQQ = SQRT(SQ)
SQR = SQRT(G10**2+SQ)
SL0 = -H11/SQQ
CL0 = -G11/SQQ
ST0 = SQQ/SQR
CT0 = G10/SQR
STCL = ST0*CL0
STSL = ST0*SL0
CTSL = CT0*SL0
CTCL = CT0*CL0
C THE CALCULATIONS ARE TERMINATED IF ONLY GEO-MAG TRANSFORMATION
C IS TO BE DONE (IHOUR>24 IS THE AGREED CONDITION FOR THIS CASE):
10 IF (IHOUR.GT.24) RETURN
CALL SUN(IY,IDAY,IHOUR,MIN,ISEC,GST,SLONG,SRASN,SDEC)
C S1,S2, AND S3 ARE THE COMPONENTS OF THE UNIT VECTOR EXGSM=EXGSE
C IN THE SYSTEM GEI POINTING FROM THE EARTH'S CENTER TO THE SUN:
S1 = COS(SRASN)*COS(SDEC)
S2 = SIN(SRASN)*COS(SDEC)
S3 = SIN(SDEC)
CGST = COS(GST)
SGST = SIN(GST)
C DIP1, DIP2, AND DIP3 ARE THE COMPONENTS OF THE UNIT VECTOR
C EZSM=EZMAG IN THE SYSTEM GEI:
DIP1 = STCL*CGST - STSL*SGST
DIP2 = STCL*SGST + STSL*CGST
DIP3 = CT0
C NOW CALCULATE THE COMPONENTS OF THE UNIT VECTOR EYGSM IN THE SYSTEM
C GEI BY TAKING THE VECTOR PRODUCT D x S AND NORMALIZING IT TO UNIT
C LENGTH:
Y1 = DIP2*S3 - DIP3*S2
Y2 = DIP3*S1 - DIP1*S3
Y3 = DIP1*S2 - DIP2*S1
Y = SQRT(Y1*Y1+Y2*Y2+Y3*Y3)
Y1 = Y1/Y
Y2 = Y2/Y
Y3 = Y3/Y
C THEN IN THE GEI SYSTEM THE UNIT VECTOR Z=EZGSM=EXGSM x EYGSM=S x Y
C HAS THE COMPONENTS:
Z1 = S2*Y3 - S3*Y2
Z2 = S3*Y1 - S1*Y3
Z3 = S1*Y2 - S2*Y1
C THE VECTOR EZGSE (HERE DZ) IN GEI HAS THE COMPONENTS (0,-SIN(DELTA),
C COS(DELTA)) = (0.,-0.397823,0.917462); HERE DELTA = 23.44214 DEG FOR
C THE EPOCH 1978 (SEE THE BOOK BY GUREVICH OR OTHER ASTRONOMICAL
C HANDBOOKS). HERE THE MOST ACCURATE TIME-DEPENDENT FORMULA IS USED:
DJ = DBLE(365*(IY-1900)+(IY-1901)/4+IDAY) - 0.5D0 +
* DBLE(ISEC)/86400.D0
T = DJ/36525.D0
OBLIQ = (23.45229D0-0.0130125D0*T)/57.2957795D0
DZ1 = 0.D0
DZ2 = -SIN(OBLIQ)
DZ3 = COS(OBLIQ)
C THEN THE UNIT VECTOR EYGSE IN GEI SYSTEM IS THE VECTOR PRODUCT DZ x S
DY1 = DZ2*S3 - DZ3*S2
DY2 = DZ3*S1 - DZ1*S3
DY3 = DZ1*S2 - DZ2*S1
C THE ELEMENTS OF THE MATRIX GSE TO GSM ARE THE SCALAR PRODUCTS:
C CHI=EM22=(EYGSM,EYGSE), SHI=EM23=(EYGSM,EZGSE),
C EM32=(EZGSM,EYGSE)=-EM23, AND EM33=(EZGSM,EZGSE)=EM22
CHI = Y1*DY1 + Y2*DY2 + Y3*DY3
SHI = Y1*DZ1 + Y2*DZ2 + Y3*DZ3
HI = ASIN(SHI)
C TILT ANGLE: PSI=ARCSIN(DIP,EXGSM)
SPS = DIP1*S1 + DIP2*S2 + DIP3*S3
CPS = SQRT(1.D0-SPS**2)
PSI = ASIN(SPS)
C THE ELEMENTS OF THE MATRIX MAG TO SM ARE THE SCALAR PRODUCTS:
C CFI=GM22=(EYSM,EYMAG), SFI=GM23=(EYSM,EXMAG); THEY CAN BE DERIVED
C AS FOLLOWS:
C IN GEO THE VECTORS EXMAG AND EYMAG HAVE THE COMPONENTS
C (CT0*CL0,CT0*SL0,-ST0) AND (-SL0,CL0,0), RESPECTIVELY. HENCE, IN
C GEI SYSTEM THE COMPONENTS ARE:
C EXMAG: CT0*CL0*COS(GST)-CT0*SL0*SIN(GST)
C CT0*CL0*SIN(GST)+CT0*SL0*COS(GST)
C -ST0
C EYMAG: -SL0*COS(GST)-CL0*SIN(GST)
C -SL0*SIN(GST)+CL0*COS(GST)
C 0
C THE COMPONENTS OF EYSM IN GEI WERE FOUND ABOVE AS Y1, Y2, AND Y3;
C NOW WE ONLY HAVE TO COMBINE THE QUANTITIES INTO SCALAR PRODUCTS:
EXMAGX = CT0*(CL0*CGST-SL0*SGST)
EXMAGY = CT0*(CL0*SGST+SL0*CGST)
EXMAGZ = -ST0
EYMAGX = -(SL0*CGST+CL0*SGST)
EYMAGY = -(SL0*SGST-CL0*CGST)
CFI = Y1*EYMAGX + Y2*EYMAGY
SFI = Y1*EXMAGX + Y2*EXMAGY + Y3*EXMAGZ
XMUT = (ATAN2(SFI,CFI)+3.1415926536D0)*3.8197186342D0
C THE ELEMENTS OF THE MATRIX GEO TO GSM ARE THE SCALAR PRODUCTS:
C A11=(EXGEO,EXGSM), A12=(EYGEO,EXGSM), A13=(EZGEO,EXGSM),
C A21=(EXGEO,EYGSM), A22=(EYGEO,EYGSM), A23=(EZGEO,EYGSM),
C A31=(EXGEO,EZGSM), A32=(EYGEO,EZGSM), A33=(EZGEO,EZGSM),
C ALL THE UNIT VECTORS IN BRACKETS ARE ALREADY DEFINED IN GEI:
C EXGEO=(CGST,SGST,0), EYGEO=(-SGST,CGST,0), EZGEO=(0,0,1)
C EXGSM=(S1,S2,S3), EYGSM=(Y1,Y2,Y3), EZGSM=(Z1,Z2,Z3)
C AND THEREFORE:
A11 = S1*CGST + S2*SGST
A12 = -S1*SGST + S2*CGST
A13 = S3
A21 = Y1*CGST + Y2*SGST
A22 = -Y1*SGST + Y2*CGST
A23 = Y3
A31 = Z1*CGST + Z2*SGST
A32 = -Z1*SGST + Z2*CGST
A33 = Z3
9000 FORMAT (/,/,1X,
* '****RECALC WARNS: YEAR IS OUT OF INTERVAL 1945-2005: IYR='
* ,I4,/,6X,'CALCULATIONS WILL BE DONE FOR IYR=',I4,/)
RETURN
END
C *********************************************************************
SUBROUTINE SUN(IYR,IDAY,IHOUR,MIN,ISEC,GST,SLONG,SRASN,SDEC)
C CALCULATES FOUR QUANTITIES NECESSARY FOR COORDINATE TRANSFORMATIONS
C WHICH DEPEND ON SUN POSITION (AND, HENCE, ON UNIVERSAL TIME AND
C SEASON)
C ---INPUT PARAMETERS:
C IYR,IDAY,IHOUR,MIN,ISEC - YEAR, DAY, AND UNIVERSAL TIME IN HOURS,
C MINUTES, AND SECONDS (IDAY=1 CORRESPONDS TO JANUARY 1).
C ---OUTPUT PARAMETERS:
C GST - GREENWICH MEAN SIDEREAL TIME, SLONG - LONGITUDE ALONG ECLIPTIC
C SRASN - RIGHT ASCENSION, SDEC - DECLINATION OF THE SUN (RADIANS)
C THIS SUBROUTINE HAS BEEN COMPILED FROM:
C RUSSELL C.T., COSM.ELECTRODYN., 1971, V.2,PP.184-196.
C AUTHOR: Gilbert D. Mead
IMPLICIT NONE
C .. Scalar Arguments ..
DOUBLE PRECISION GST,SDEC,SLONG,SRASN
INTEGER IDAY,IHOUR,ISEC,IYR,MIN
C ..
C .. Local Scalars ..
DOUBLE PRECISION COSD,DJ,FDAY,G,OBLIQ,RAD,SC,SIND,SLP,SOB,T,VL
C ..
C .. Intrinsic Functions ..
INTRINSIC DATAN,DATAN2,DCOS,DBLE,DMOD,DSIN,SQRT
C ..
C .. Data statements ..
DATA RAD/57.295779513D0/
C ..
IF (IYR.LT.1901 .OR. IYR.GT.2099) RETURN
FDAY = DBLE(IHOUR*3600+MIN*60+ISEC)/86400.D0
DJ = 365*(IYR-1900) + (IYR-1901)/4 + IDAY - 0.5D0 + FDAY
T = DJ/36525.D0
VL = DMOD(279.696678D0+0.9856473354D0*DJ,360.D0)
GST = DMOD(279.690983D0+.9856473354D0*DJ+360.D0*FDAY+180.D0,
* 360.D0)/RAD
G = DMOD(358.475845D0+0.985600267D0*DJ,360.D0)/RAD
SLONG = (VL+(1.91946D0-0.004789D0*T)*SIN(G)+
* 0.020094D0*SIN(2.D0*G))/RAD
IF (SLONG.GT.6.2831853D0) SLONG = SLONG - 6.2831853D0
IF (SLONG.LT.0.D0) SLONG = SLONG + 6.2831853D0
OBLIQ = (23.45229D0-0.0130125D0*T)/RAD
SOB = SIN(OBLIQ)
SLP = SLONG - 9.924D-5
C THE LAST CONSTANT IS A CORRECTION FOR THE ANGULAR ABERRATION
C DUE TO THE ORBITAL MOTION OF THE EARTH
SIND = SOB*SIN(SLP)
COSD = SQRT(1.D0-SIND**2)
SC = SIND/COSD
SDEC = ATAN(SC)
SRASN = 3.141592654D0 - ATAN2(COS(OBLIQ)/SOB*SC,-COS(SLP)/COSD)
RETURN
END
C *********************************************************************
SUBROUTINE SPHCAR(R,TETA,PHI,X,Y,Z,J)
C CONVERTS SPHERICAL COORDS INTO CARTESIAN ONES AND VICA VERSA
C (TETA AND PHI IN RADIANS).
C J>0 J<0
C -----INPUT: J,R,TETA,PHI J,X,Y,Z
C ----OUTPUT: X,Y,Z R,TETA,PHI
C AUTHOR: NIKOLAI A. TSYGANENKO, INSTITUTE OF PHYSICS, ST.-PETERSBURG
C STATE UNIVERSITY, STARY PETERGOF 198904, ST.-PETERSBURG, RUSSIA
C (now the NASA Goddard Space Fligth Center, Greenbelt, Maryland)
IMPLICIT NONE
C .. Scalar Arguments ..
DOUBLE PRECISION PHI,R,TETA,X,Y,Z
INTEGER J
C ..
C .. Local Scalars ..
DOUBLE PRECISION SQ
C ..
C .. Intrinsic Functions ..
INTRINSIC DATAN2,DCOS,DSIN,SQRT
C ..
IF (J.GT.0) GO TO 30
SQ = X**2 + Y**2
R = SQRT(SQ+Z**2)
IF (SQ.NE.0.D0) GO TO 20
PHI = 0.D0
IF (Z.LT.0.D0) GO TO 10
TETA = 0.D0
RETURN
10 TETA = 3.141592654D0
RETURN
20 SQ = SQRT(SQ)
PHI = ATAN2(Y,X)
TETA = ATAN2(SQ,Z)
IF (PHI.LT.0.D0) PHI = PHI + 6.28318531D0
RETURN
30 SQ = R*SIN(TETA)
X = SQ*COS(PHI)
Y = SQ*SIN(PHI)
Z = R*COS(TETA)
RETURN
END
C *********************************************************************
SUBROUTINE BSPCAR(TETA,PHI,BR,BTET,BPHI,BX,BY,BZ)
C CALCULATES CARTESIAN FIELD COMPONENTS FROM SPHERICAL ONES
C -----INPUT: TETA,PHI - SPHERICAL ANGLES OF THE POINT IN RADIANS
C BR,BTET,BPHI - SPHERICAL COMPONENTS OF THE FIELD
C -----OUTPUT: BX,BY,BZ - CARTESIAN COMPONENTS OF THE FIELD
C AUTHOR: NIKOLAI A. TSYGANENKO, INSTITUTE OF PHYSICS, ST.-PETERSBURG
C STATE UNIVERSITY, STARY PETERGOF 198904, ST.-PETERSBURG, RUSSIA
C (now the NASA Goddard Space Fligth Center, Greenbelt, Maryland)
IMPLICIT NONE
C .. Scalar Arguments ..
DOUBLE PRECISION BPHI,BR,BTET,BX,BY,BZ,PHI,TETA
C ..
C .. Local Scalars ..
DOUBLE PRECISION BE,C,CF,S,SF
C ..
C .. Intrinsic Functions ..
INTRINSIC DCOS,DSIN
C ..
S = SIN(TETA)
C = COS(TETA)
SF = SIN(PHI)
CF = COS(PHI)
BE = BR*S + BTET*C
BX = BE*CF - BPHI*SF
BY = BE*SF + BPHI*CF
BZ = BR*C - BTET*S
RETURN
END
C *********************************************************************
SUBROUTINE GEOMAG(XGEO,YGEO,ZGEO,XMAG,YMAG,ZMAG,J,IYR)
C CONVERTS GEOCENTRIC (GEO) TO DIPOLE (MAG) COORDINATES OR VICA VERSA.
C IYR IS YEAR NUMBER (FOUR DIGITS).
C J>0 J<0
C -----INPUT: J,XGEO,YGEO,ZGEO,IYR J,XMAG,YMAG,ZMAG,IYR
C -----OUTPUT: XMAG,YMAG,ZMAG XGEO,YGEO,ZGEO
C AUTHOR: NIKOLAI A. TSYGANENKO, INSTITUTE OF PHYSICS, ST.-PETERSBURG
C STATE UNIVERSITY, STARY PETERGOF 198904, ST.-PETERSBURG, RUSSIA
C (now the NASA Goddard Space Fligth Center, Greenbelt, Maryland)
IMPLICIT NONE
C .. Scalar Arguments ..
DOUBLE PRECISION XGEO,XMAG,YGEO,YMAG,ZGEO,ZMAG
INTEGER IYR,J
C .. Modified by Bill Rideout to simply call Geopack_2005
EXTERNAL TS_GEOMAG_08,TS_RECALC_08
call TS_RECALC_08(IYR,180,0,0,0,0.0,29.8,0.0)
CALL TS_GEOMAG_08(XGEO,YGEO,ZGEO,XMAG,YMAG,ZMAG,J)
RETURN
END
C *********************************************************************
SUBROUTINE MAGSM(XMAG,YMAG,ZMAG,XSM,YSM,ZSM,J)
C CONVERTS DIPOLE (MAG) TO SOLAR MAGNETIC (SM) COORDINATES OR VICA VERSA
C J>0 J<0
C -----INPUT: J,XMAG,YMAG,ZMAG J,XSM,YSM,ZSM
C ----OUTPUT: XSM,YSM,ZSM XMAG,YMAG,ZMAG
C ATTENTION: SUBROUTINE RECALC MUST BE CALLED BEFORE MAGSM IN TWO CASES
C /A/ BEFORE THE FIRST USE OF MAGSM
C /B/ IF THE CURRENT VALUES OF IYEAR,IDAY,IHOUR,MIN,ISEC ARE
C DIFFERENT FROM THOSE IN THE PRECEDING CALL OF MAGSM
C AUTHOR: NIKOLAI A. TSYGANENKO, INSTITUTE OF PHYSICS, ST.-PETERSBURG
C STATE UNIVERSITY, STARY PETERGOF 198904, ST.-PETERSBURG, RUSSIA
C (now the NASA Goddard Space Fligth Center, Greenbelt, Maryland)
IMPLICIT NONE
C .. Scalar Arguments ..
DOUBLE PRECISION XMAG,XSM,YMAG,YSM,ZMAG,ZSM
INTEGER J
C ..
C .. Common blocks ..
COMMON /C1/A,SFI,CFI,B,AB,K,IY,BA
DOUBLE PRECISION CFI,SFI
INTEGER IY,K
DOUBLE PRECISION A(8),AB(10),B(7),BA(8)
SAVE /C1/
C ..
IF (J.LT.0) GO TO 10
XSM = XMAG*CFI - YMAG*SFI
YSM = XMAG*SFI + YMAG*CFI
ZSM = ZMAG
RETURN
10 XMAG = XSM*CFI + YSM*SFI
YMAG = YSM*CFI - XSM*SFI
ZMAG = ZSM
RETURN
END
C *********************************************************************
SUBROUTINE SMGSM(XSM,YSM,ZSM,XGSM,YGSM,ZGSM,J)
C CONVERTS SOLAR MAGNETIC (SM) TO SOLAR MAGNETOSPHERIC (GSM) COORDINATES
C OR VICA VERSA.
C J>0 J<0
C -----INPUT: J,XSM,YSM,ZSM J,XGSM,YGSM,ZGSM
C ----OUTPUT: XGSM,YGSM,ZGSM XSM,YSM,ZSM
C ATTENTION: SUBROUTINE RECALC MUST BE CALLED BEFORE SMGSM IN TWO CASES
C /A/ BEFORE THE FIRST USE OF SMGSM
C /B/ IF THE CURRENT VALUES OF IYEAR,IDAY,IHOUR,MIN,ISEC ARE
C DIFFERENT FROM THOSE IN THE PRECEDING CALL OF SMGSM
C AUTHOR: NIKOLAI A. TSYGANENKO, INSTITUTE OF PHYSICS, ST.-PETERSBURG
C STATE UNIVERSITY, STARY PETERGOF 198904, ST.-PETERSBURG, RUSSIA
C (now the NASA Goddard Space Fligth Center, Greenbelt, Maryland)
IMPLICIT NONE
C .. Scalar Arguments ..
DOUBLE PRECISION XGSM,XSM,YGSM,YSM,ZGSM,ZSM
INTEGER J
C ..
C .. Common blocks ..
COMMON /C1/A,SPS,CPS,B,K,IY,AB
DOUBLE PRECISION CPS,SPS
INTEGER IY,K
DOUBLE PRECISION A(10),AB(8),B(15)
SAVE /C1/
C ..
IF (J.LT.0) GO TO 10
XGSM = XSM*CPS + ZSM*SPS
YGSM = YSM
ZGSM = ZSM*CPS - XSM*SPS
RETURN
10 XSM = XGSM*CPS - ZGSM*SPS
YSM = YGSM
ZSM = XGSM*SPS + ZGSM*CPS
RETURN
END