In this file the satellite positions and the geomagnetic parameteres are calculated with 5 min step for the time intervals near the CUSP region passing. Each points are labeled by the region names .

The column designation and parameter description:

no:        The orbit number
MTyymmdd:  Year, Month, Day
Thhmnss:   Hours, Min, Sec (Moscow time = UT +3 h) 
name:      Region  name 
Hs(km):    The altitude (above the Spherical Earth)  
R RE:      The satellite geocentric distance (units Earth's radii) 
L (RE):    The  geocentric  distance to the magnetic field line 
           point located in  the equatorial plane of the magnetic dipole
CGL:       The corrected geomagnetic latitude  (deg) 
CCGL:      The Tilt compensated corrected geomagnetic latitude  (deg)
CMLT:      The Corrected Geomagnetic local time (hours) 
CGMLN:     The Corrected Geomagnetic longitude (deg) 
GLTF:      The geocentric geographical latitude of the footprint (deg)
GLONF:     The geographical longitude of the footprint (deg)    
GLAT:      The satellite geocentric geographical latitude (deg)   
GLON:      The satellite geographical longitude (deg)

Footprint is the point on the Earth's Ionosphere (100 km above the Earth surface), which is connected with satellite by magnetic field line. This point is produced by magnetic field line tracing, using the IGRF + Tsyganenco 87 magnetic field model, corresponding to the middle level of the magnetic activity (KP=2)

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Algorithm used for calculation of the L value, corrected geomagnetic latitude (CGL), longitude (CMLON) and local time (CMLT) :

Step 1: The Footprint position calculation by the magnetic field line tracing from the satellite to the Ionosphere, by using IGRF + Tsyganenko 87 magnetic field model.

Step 2: Tracing from the Footprint to the dipole equatorial plane (by using only IGRF magnetic field model up to the geocentric distance 8 RE and dipole field model after this distance).

Step 3: The CMLON and CMLT of the original point are equal to the dipole longitude and local time of the point, produced in the step 2.

Step 4: The L value is the geocentric distance of the point, produced in the step 2.

Step 5: The CGL is found from the equation: (cos CGL)**2=R/L, where R is geocentric distance of the original point.

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The tilt compensated corrected geomagnetic latitude (CCGL) is used for the Cusp region identifying according to the K.Stasiewicz 1991 model. This parameter compensate the corrected geomagnetic latitude by -.08 deg per 1 deg of the dipole tilt for low magnetic activity (and by -.12 deg per 1 deg of the tilt for high activity). Tilt is geomagnetic latitude of the Sun. During Cusp region prediction, when the magnetic activity level is unknown the coefficient -.1 is used for the tilt compensation.

The CUSP region is identified on the base of the CCGL and CMLT values. According to the K.Stasiewicz 1991 for various level of the magnetic activity the CCGL of the CUSP region varies in the range 74 - 79 deg, CMLT is equal to 12 h. During the Cusp region predictions the following boxes of the mentioned parameters are used: 73 deg < CCGL < 80 deg, 9 h < CMLT < 15 h.

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The others geomagnetic regions identifying

The list of the region names designation used in the numerical file

Solar Wind                      SOW
Bows hock                       BSH
Magnetosheath                   MSH
Magnetosphere                   MSP      
Magnetopause                    MPA
Magnetospheric Boundary Layer   MBL
Tail Lobe                       LOB
Plasma Sheet                    PSH
Neutral Sheet                   NSH
Auroral Zone                    AUR
Polar Cap                       POC
Cusp                            CSP
Radiation Belts                 RBT
Earth's Shadow Region           ECL

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REFERENCES

• Stasiewicz K. Polar Cusp Topology and Position as a Function of Interplanetary Magnetic Field and Magnetic Activity: Comparison of a Model with Viking and other Observations, J. Geophys. Res., 96, 15789-15800, September 1, 1991.

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• Tsyganenko N.A., Global quantitative models of the geomagnetic field in the cislunar magnetosphere for different disturbance levels, Planet.Space Sci., 35, 1347-1358, 1987.

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Victoria Prokhorenko

Last updated 17 January 1996