[1] We present results of in situ measurements of charged nanoparticles, electrons, and positive ions obtained during a sounding rocket flight in October 2004 from Kiruna, Sweden, under nighttime conditions. The particle measurement reveals positive charge signatures in the altitude range between 80 and 90 km corresponding to peak charge number densities of $100 e/cm 3 at around 86 km. Aerodynamical analysis of the sampling efficiency of our instrument reveals that the particles must have been larger than 2 nm assuming spherical particles with a density of 3 g/cm 3 . The plasma environment of the observed particles is dominated by negative and positive ions, with only few free electrons. A calculation of the mean particle charge expected for particles in a plasma consisting of electrons and positive and negative ions shows that the presence of sufficiently heavy and numerous negative ions (i.e., m n > 300 amu and l ! 50) can explain the observed positive particle charge. Citation:

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[1] We present a new algorithm to infer information on the properties of charged meteoric smoke particles (MSPs) from the shape of incoherent scatter radar spectra. We show that in the presence of charged MSPs the spectrum can be approximated as the sum of two Lorentzians. These two distinct spectral lines correspond to two diffusion modes in the D-region plasma, i.e., one due the presence of positive ions and one because of heavy charged MSPs. The widths and amplitudes of these two spectral lines yield information on the radius and number density (the latter only for positively charged particles) of the charged MSPs. We apply this new algorithm to measurements obtained with the 430 MHz ISR at Arecibo and demonstrate that the observed spectra indeed bear the features anticipated in the presence of charged MSPs. Resulting values of retrieved MSP number densities and radii fall well within the range of values expected from models and independent in situ observations. Citation: Strelnikova, I., M. Rapp, S. Raizada, and M. Sulzer (2007), Meteor smoke particle properties derived from Arecibo incoherent scatter radar observations, Geophys. Res. Lett., 34, L15815,

Nonspecular meteor echoes have been associated with field‐aligned irregularities and have been observed at low‐latitude and midlatitude sites. We present observations obtained at high latitudes with range‐time features that resemble those at lower latitudes. However, these echoes cannot come from field‐aligned irregularities, since the radar‐pointing angles are almost parallel to the magnetic field. Using interferometry, we have been able to discriminate space and time features. Our echoes could be qualitatively explained by the presence of charged dust forming from the meteoric material immersed in a turbulent flow. This can lead to a high Schmidt number plasma that can sustain meter‐scale turbulence just as it does for the polar mesospheric summer echoes. These rare events require relatively large meteoroids. The result emphasizes the importance of charged dust in understanding all long‐duration nonspecular meteor echoes. This dust will extend their diffusion times and will affect temperature estimations from specular echoes.