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The M-dwarf AD Leonis has been observed with the Reflection GratingSpectrometers and the European Photon Imaging Camera aboard XMM-Newton and alsowith the Low Energy Transmission Grating Spectrometer aboard the Chandra X-rayObservatory. In the observation taken with XMM-Newton five large flaresproduced by AD Leo were identified and only one in the observation taken withChandra. A quiescent level to the lightcurves is difficult to define, sinceseveral smaller flares mutually overlap each other. However, we defined aquasi-steady state outside of obvious flares or flare decays. The spectra fromthe flare state and the quasi-steady state are analysed separately. From thesespectra the temperature structure was derived with a multi-temperature modeland with a differential emission measure model. The multi-temperature model wasalso used to determine the relative abundances of C, N, O, Ne, Mg, Si, S, andFe. He-like ions, such as O VII and Ne IX, produce line triplets which are usedto determine or constrain the electron temperature and electron density of thecorresponding ion. During the flare state a higher emission measure at thehottest temperature is found for both XMM-Newton and Chandra observations. Thederived abundances suggest the presence of an inverse First IonizationPotential effect in the corona of AD Leo.Comment: 8 pages and 7 figures. Accepted for publication in Astronomy &  Astrophysic

AD Leonis: Flares observed by XMM-Newton and Chandra