JOP170 Magnetic Field Temporal Changes over the Active Regions: From the Photoshpre to the Corona.

Short title: JOP170 AR Magnetic Field Temporal Changes

Proposal of coordinated observations with THEMIS and space instruments

PI:   J.-M. Malherbe (OP/LESIA)

CoI:  G. Chambe (OP/LESIA), B.Schmieder  (OP/LESIA)

Objectives: 

The aim of this proposal is to determine the vertical gradients of the magnetic field. 
THEMIS with its multi lines observations can lead to maps of the vector  magnetic 
field  and the Doppler shifts at different altitudes (photosphere and chromosphere). 
Theoretical computations using extrapolation codes allow to map the coronal magnetic 
field and compare it with the observations of the coronal loops.

Details of the proposal:
According to the opportunity of the observations specific programs have been defined.

Programme 1:
Magnetic field evolution during flux emergence. 
With THEMIS  we will observe 2 lines in a field of view of 2' x 2' evry 30 min.
The active region should be located not to far from the central meridian.
Space observations: TRACE and MDI high resolution observations.

Programme 2.
Magnetic field evolution during the decreasing phase of active region.
We would like to evaluate the decreasing flux due to the "moving magnetic features"
The extrapolation will be done by using the French data base FROMAGE 
(http://helios.obspm.fr/fromage)
The comparison of the magnetic field lines with the TRACE or EIT coronal loops
will fix the value of alpha. The extrapolated lines would indicate a typical 
magnetic gradient in the atmosphere which will be compared with the THEMIS observation. 
Such work has already started (Eibe et al. A et A 2002).

Programme 3.
Formation of U loops between active regions predicted by models
of emerging active regions (Van Driel et al, A et A, 2001) .
THEMIS will observe large field of view 2' x 8' par example with B//.
The loops can be observed by the fast  displacement of pores.

space instruments: TRACE or SOHO/EIT and MDI

Programme 4.
Instabilities in active region , onset of flares.
THEMIS will observe within a fast cadence on alert.
Space instruments: TRACE, SOHO/EIT, CDS



THEMIS lines : 6301/6302 FeI, facteur de Landé 1.67/2.5, altitude 200 km
8688 FeI, facteur de Landé 1.67, altitude 400 km
and CaII 8542, facteur de Landé 1.1, altitude 800 - 1200 km

Space instruments: TRACE, CDS, EIT, MDI

Jean-Marie MALHERBE
Observatoire de Paris
Section de Meudon
LESIA
5 place Jules Janssen