MIRACLE data analysis tools
field continuation of the X component of a north-south IMAGE
chain to the ionosphere; electrojet detection:
- Short description of the
The X component data of a 1D
chain is continued upward to the iononsphere. Two versions of this
method are existing:
1.) A version that works in cartesian coordinates and uses the field continuation operator in
space (see Mersmann et al.,
2.) A version that works in spherical coordinates and uses 1D Spherical
Elementary Current Systems (SECS) (see Vanhamäki et al., 2003).
The upward continuation can be performed with both versions quickly for a whole range of time.
- Input data requirements:
IMAGE magnetometer data of the
NUR-NAL (X components; see MIRACLE
map for stations overview). Additionally, the east-west chain
AND-KEV is used to estimate the validity of the 1D assumption.
- Output quantities:
Upward continued X component on the ionospheric height,
spaced on a north-south profile.
- Mersmann, U., Baumjohann,
F., and Lange, K., Analysis of an eastward electrojet by means of
continuation of ground-based magnetometer data, J. Geophys., 45,
- Untiedt, J., and
of polar current systems using the IMS Scandinavian Magnetometer Array,
Sci. Rev., 63, 245, 1993.
- Vanhamäki, H., O. Amm, and A. Viljanen, 1-dimensional
continuation of the ground magnetic field disturbance using spherical
elementary current systems, Earth Planets Space, 55, 613, 2003.
- Example plots:
- This is the input
data: measured X components of MIRACLE
magnetometers on January 23, 1999, as they can be found in the IMAGE
online magnetogram page. For the analysis, we use an approximately
north-south aligned chain of stations, reaching from NUR to NAL (see MIRACLE
- This plot shows the
upward continued X component (on the ionospheric height) during
the interval 16-20 UT (for these plots,
the cartesian version of the method has been used):
- Detection of eastward
and westward electrojets is then easy,
since they are just bounded by the X=0 lines; they can be displayed
by showing only the positive or negative part of the above figure:
Note that multiplication of BIon
with 2 /0gives
directly the (equivalent) current density of the electrojets in the
For further questions contact Olaf
Amm or Heikki Vanhamäki.
Maintained by: Olaf
Latest update: 02.04.2004