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Energy Input from the Exterior Cusp
into the Ionosphere: Correlated GroundBased and Satellite Observations
Yordanova, E., D. Sundkvist, S. C. Buchert, M.
André, Y. Ogawa, M. Morooka, O. Margithu,
O. Amm, A. N. Fazakerley, and H. Réme
GRL, 34, L04102, doi:10.1029/2006GL028617
February 1, 2002 cusp event
(a) Cluster position in the Tsyganenko 2001 model.
(b) Cluster magnetic footprints with the location of the EISCAT
Svalbard radar and MIRACLE magnetometers at the
ground-based stations NAL, LYR, HOR and HOP.
EISCAT observations
(a) electron density; (b) electron temperature;
(c) ion temperature; (d) energy flux
Estimation of the energy flux in the F-region
of the ionospheric cusp
Integration over altitudes (250-600 km) of the cooling rates
of the electrons due to elastic and inelastic processes:
Coulomb collisions of electrons with ambient ions;
elastic collisions of electrons with neutrals;
rotational and vibrational excitations of molecular neutrals;
 fine structure excitation of the atomic oxygen;
excitation of the lowest electronic state of the atomic
oxygen.
Cluster observations
(a) electron differential
energy spectrogram
(spacecraft 3).
(b) ion differential
energy
spectrogram;
(c) up- and downgoing
(positive,
earthward) electron
energy flux
(d) up- and downgoing
ion energy flux,
(e) the GSE
components of the
electric field ;
(f) the GSE
components (in
colors) of the
magnetic field
Estimation of the Joule heating
in the ionosphere
Q  E 2 p
, where
E  J eq ,ion / h
J eq ,ion
technique of 2D upward
continuation based on
magnetometers data (MIRACLE)
 p , h
(EISCAT)
Results
(a) The Poynting flux on
Cluster - positive toward
the Earth;
(b) downgoing electron
energy flux (spacecraft 14);
(c) downgoing ion energy
flux (spacecraft 1 and 3);
(d) total particle energy flux
(spacecraft 1 and 3) and
EISCAT energy input;
(e) equivalent ionospheric
current density
(MIRACLE);
(f) height--integrated
Pedersen and Hall
conductivities (EISCAT);
(g) ionospheric electric field
strength;
(h) the 1-minute averaged
Poynting flux and the
Joule heating
Conclusions:
• the direct magnetosheath soft plasma precipitation into
the ionosphere is responsible for the heating of the Fregion of the cusp.
• more than enough Poynting flux for the heating of the
E-region of the cusp (part of it goes to the Joule
heating, the other pars may cause other phenomena).