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[1] A field campaign designed to investigate the second indirect aerosol effect (reduction of precipitation by anthropogenic aerosols which produce more numerous and smaller cloud droplets) was conducted during winter in the northern Rocky Mountains of Colorado. Combining remote sensing and in-situ mountain-top measurements it was possible to show higher concentrations of anthropogenic aerosols ($1 mg m À3) altered the microphysics of the lower orographic feeder cloud to the extent that the snow particle rime growth process was inhibited, or completely shut off, resulting in lower snow water equivalent precipitation rates.

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International audienceThe Concordiasi project is making innovative observations of the atmosphere above Antarctica. The most important goals of the Concordiasi are as follows: 1. To enhance the accuracy of weather prediction and climate records in Antarctica through the assimilation of in situ and satellite data, with an emphasis on data provided by hyperspectral infrared sounders. The focus is on clouds, precipitation, and the mass budget of the ice sheets. The improvements in dynamical model analyses and forecasts will be used in chemical-transport models that describe the links between the polar vortex dynamics and ozone depletion, and to advance the understanding of the Earth system by examining the interactions between Antarctica and lower latitudes. 2. To improve our understanding of microphysical and dynamical processes controlling the polar ozone, by providing the first quasi-Lagrangian observations of stratospheric ozone and particles, in addition to an improved characterization of the 3D polar vortex dynamics. Techniques for assimilating these Lagrangian observations are being developed. A major Concordiasi component is a field experiment during the austral springs of 2008-10. The field activities in 2010 are based on a constellation of up to 18 long-duration stratospheric super-pressure balloons (SPBs) deployed from the McMurdo station. Six of these balloons will carry GPS receivers and in situ instruments measuring temperature, pressure, ozone, and particles. Twelve of the balloons will release drop-sondes on demand for measuring atmospheric parameters. Lastly, radiosounding measurements are collected at various sites, including the Concordia station

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[1] Cross-beam wind is usually estimated using a full correlation analysis (FCA) method applied to signals from spaced antennas. In this paper we present a cross-correlation ratio (CCR) method for wind measurements. The CCR method is illustrated using theory, and data obtained with the National Center for Atmospheric Research's multiple antenna profiling radar. The standard errors of estimated cross-beam wind using CCR and a FCA are studied based on a rigorous analysis of the variance of the cross-correlation estimates. The results of the analysis are compared with previous works. It is shown that the current method is easy to implement and has smaller error for receiving antenna spacing small compared to the transmitting antenna dimensions.

Abstract. In part 1 of this paper we developed analytic relationships linking the cross correlation and cross spectrum of the echoes from a spaced antenna system to the properties of a horizontally isotropic scattering medium (e.g., clear-air refractive index irregularities) and the background flow (e.g., laminar or isotropic turbulent flow). Using these analytic expressions, in the present paper, part 2, we construct algorithms (for both the time domain and frequency domain) for extracting unbiased wind and turbulence estimates. We derive a condition under which one can ignore turbulence when computing winds from the time delay to the peak of the cross-correlation functions. We show profiles of the horizontal wind and turbulence based on these algorithms using data from the unique 33-cm wavelength spaced antenna wind profiler developed by the National Center for Atmospheric Research.

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