European Space Agency¶
Royal Belgian Institute for Aeronomy¶
Ex #4. Find the point with the lowest altitude on a magnetic drift shell¶
Description¶
In this example, a magnetic drift shell is traced for a given (B, L) coordinate and the geographic locations of the northern and southern points with the lowest altitude are printed. The GSFC 12/66 magnetic field model is used to trace the drift shell.
Note that subroutine UD317 can be used instead of subroutine UD310 (see note).
Source¶
PROGRAM example4
C
INCLUDE 'unilib.h'
C
INTEGER*4 kunit, kinit, ifail, kint, kext
CHARACTER*32 lbint, lbext
REAL*8 year, param(10), amjd
INTEGER*4 knfl, ktyplus
REAL*8 fbm0, flm0, falt
TYPE(ZGEO) mpn, mps
C
C initialize variables
C
DATA kunit, kinit/ 6, 1/
DATA kint, kext/ 2, 0/
DATA year, param, amjd/ 1970.d0, 10*0.d0, 0.d0/
C
C initialize the library
C
CALL UT990 (kunit, kinit, ifail)
IF( ifail .LT. 0 )STOP
C
C set the geomagnetic field model
C (kint=2, GFSC 12/66)
C
CALL UM510 (kint, year, lbint, kunit, ifail)
IF( ifail .LT. 0 )STOP
C
C set no external magnetic field model
C
CALL UM520 (kext, amjd, param,
: lbext, kunit, ifail)
IF( ifail .LT. 0 )STOP
C
C trace the drift shell
C
fbm0 = 0.19d0
flm0 = 2.0d0
falt = -999.9d0
knfl = 60
ktyplus = 3
C
CALL UD310 (fbm0, flm0, falt, knfl,
: ktyplus, ifail)
IF( ifail .LT. 0 )STOP
C
CALL UD315 (mpn, mps, ifail)
IF( ifail .LT. 0 )STOP
C
C write the result
C
WRITE (kunit,1000) mpn%radius, mpn%colat, mpn%elong,
: mps%radius, mps%colat, mps%elong
C
1000 FORMAT(
: /25('-'),/'RESULT: coordinates (radius, colatitude, longitude)',
: ' of the points with the lowest altitude',
: /'North : ', 3f20.10,
: /'South : ', 3f20.10,
: /25('-') )
C
END
Results¶
SPENVIS
UNILIB Library
Version 2.22_YCH_initPrep
Generated by SPENVIS team
--- Main control parameters ---
UC160 (general constants):
Geoid major axis = 6378.16 km
Geoid minor axis = 6356.77 km
Mean Earth radius (Re) = 6371.20 km
Ecliptic inclination = 23.441512 deg
McIlwain Earth dipole = 0.311653 G/Re^3
UC190 (field line tracing):
Maximum step size = 477.8 km at one Re
Maximum "last" step size = 15.0 km
Minimum step size = 2.0 km
Altitude precision = 200. m
Magnetic field precision = 0.0006 %
UC192 (magnetic field evaluation):
Max. geomagnetic latitude = 85.0 deg
Minimum radius = 0.157 Re
(drift shell tracing):
Precision on L = 0.10000 %
Precision on the longitude = 0.05 deg
--- Geomagnetic field model ---
Model ( 2): GSFC 12/66 120 Term Epoch 1960.
Order + 1 = 11
Calculation epoch = 1970.0 year
Colatitude of the dipole pole = 11.39 deg
Longitude of the dipole pole = -70.21 deg
Earth dipole moment = 0.308751 G/Re^3
Correction for the SAA drift = 0.00 deg
--- External magnetic field model ---
Model ( 0): None
Planetary activity index Kp = 0.0 (magnetopause check)
Date = 01-Jan-1950
Universal Time = 0.00 hrs
Greenwich angle of equinox = 100.08 deg
GEO direction of the Sun, X = -0.9200
Y = -0.0131
Z = -0.3918
Dipole tilt angle = -26.30 deg
-------------------------
RESULT: coordinates (radius, colatitude, longitude) of the points with the lowest altitude
North : 8304.0286038063 59.8894733083 -34.6062461396
South : 7492.5608715705 131.3611545561 -10.3147983474
-------------------------
UNILIB/tags/v3.02
