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In this work we use ion and magnetic field\uddata from the AMPTE-UKS mission to study the characteristics of low frequency\ud(ωr &#x00ab; Ωp) waves observed upstream of the\udEarth's bow shock. We test the application of various plasma-field correlations\udand magnetic ratios derived from linear Vlasov theory to identify the modes in\udthis region. We evaluate (for a parameter space consistent with the ion\udforeshock) the Alfvén ratio, the parallel compressibility, the cross-helicity,\udthe noncoplanar ratio, the magnetic compression and the polarization for the two\udkinetic instabilities that can be generated in the foreshock by the interaction\udof hot diffuse ions with the solar wind: the left-hand resonant and the\udright-hand resonant ion beam instabilities. Comparison of these quantities with\udthe observed plasma-field correlations and various magnetic properties of the\udwaves observed during 10 intervals on 30 October 1984, where the waves are\udassociated with diffuse ions, allows us to identify regions with Alfvénic waves\udand regions where the predominant mode is the right-hand resonant instability.\udIn all the cases the waves are transverse, propagating at angles ≤ 33° and are elliptically polarized. Our results suggest that while\udthe observed Alfvén waves are generated locally by hot diffuse ions, the\udright-handed waves may result from the superposition of waves generated by two\uddifferent types of beam distribution (i.e. cold beam and diffuse ions). Even\udwhen there was good agreement between the values of observed transport ratios\udand the values given by the theory, some discrepancies were found. This shows\udthat the observed waves are different from the theoretical modes and that mode\udidentification based only on polarization quantities does not give a complete\udpicture of the waves' characteristics and can lead to mode identification of\udwaves whose polarization may agree with theoretical predictions even when other\udproperties can diverge from those of the theoretical modes

Identification of low-frequency kinetic wave modes in the Earth's ion foreshock