  The M-dwarf AD Leonis has been observed with the Reflection Grating
Spectrometers and the European Photon Imaging Camera aboard XMM-Newton and also
with the Low Energy Transmission Grating Spectrometer aboard the Chandra X-ray
Observatory. In the observation taken with XMM-Newton five large flares
produced by AD Leo were identified and only one in the observation taken with
Chandra. A quiescent level to the lightcurves is difficult to define, since
several smaller flares mutually overlap each other. However, we defined a
quasi-steady state outside of obvious flares or flare decays. The spectra from
the flare state and the quasi-steady state are analysed separately. From these
spectra the temperature structure was derived with a multi-temperature model
and with a differential emission measure model. The multi-temperature model was
also used to determine the relative abundances of C, N, O, Ne, Mg, Si, S, and
Fe. He-like ions, such as O VII and Ne IX, produce line triplets which are used
to determine or constrain the electron temperature and electron density of the
corresponding ion. During the flare state a higher emission measure at the
hottest temperature is found for both XMM-Newton and Chandra observations. The
derived abundances suggest the presence of an inverse First Ionization
Potential effect in the corona of AD Leo.
