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International audience; Contrails can persist in cloud-free supersaturated air, increasing high-cloud cover, and inside natural cirrus cloud, modifying the microphysical properties of them. The latter effect is almost unknown, partly because of the lack of height-resolved measurements and the capability of measurements to penetrate inside the cloud. New retrievals of the ice crystal number concentration from combined satellite cloud radar and lidar measurements (CloudSat/CALIPSO; DARDAR-Nice algorithm) now allow for satellite-based assessment inside the clouds. We investigate this issue at intersections between the aircraft flight tracks and these retrieval profiles. Regions behind the aircraft inside the flight track were compared to the adjacent regions and to ahead of the aircraft, along the satellites' profiles, where DARDAR-Nice identify geometrically thin cirrus clouds. This comparison revealed a statistically significant increase of 25% and 54% in the concentration of ice crystals with the minimum size of 5 μm around 300-540-m beneath an aircraft's flight altitude.

A global vertically resolved aerosol data set covering more than 10 years of observations at more than 20 measurement sites distributed from 63° N to 52° S and 72° W to 124° E has been achieved within the Raman and polarization lidar network PollyNET. This network consists of portable, remote-controlled multiwavelength-polarization-Raman lidars (Polly) for automated and continuous 24/7 observations of clouds and aerosols. PollyNET is an independent, voluntary, and scientific network. All Polly lidars feature a standardized instrument design with different capabilities ranging from single wavelength to multiwavelength systems, and now apply unified calibration, quality control, and data analysis. The observations are processed in near-real time without manual intervention, and are presented online at http://polly.tropos.de/. The paper gives an overview of the observations on four continents and two research vessels obtained with eight Polly systems. The specific aerosol types at these locations (mineral dust, smoke, dust-smoke and other dusty mixtures, urban haze, and volcanic ash) are identified by their Ångström exponent, lidar ratio, and depolarization ratio. The vertical aerosol distribution at the PollyNET locations is discussed on the basis of more than 55 000 automatically retrieved 30 min particle backscatter coefficient profiles at 532 nm as this operating wavelength is available for all Polly lidar systems. A seasonal analysis of measurements at selected sites revealed typical and extraordinary aerosol conditions as well as seasonal differences. These studies show the potential of PollyNET to support the establishment of a global aerosol climatology that covers the entire troposphere.

The particle linear depolarization ratio δp of Saharan dust, marine aerosols and mixtures of biomass-burning aerosols from southern West Africa and Saharan dust was determined at three wavelengths with three lidar systems during the SAharan Mineral dUst experiMent 2 at the airport of Praia, Cape Verde, between 22 January and 9 February 2008. The lidar ratio Sp of these major types of tropospheric aerosols was analysed at two wavelengths. For Saharan dust, we find wavelength dependent mean particle linear depolarization ratios δp of 0.24–0.27 at 355 nm, 0.29–0.31 at 532 nm and 0.36–0.40 at 710 nm, and wavelength independent mean lidar ratios Sp of 48–70 sr. Mixtures of biomass-burning aerosols and dust show wavelength independent values of δp and Sp between 0.12–0.23 and 57–98 sr, respectively. The mean values of marine aerosols range independent of wavelength for δp from 0.01 to 0.03 and for Sp from 14 to 24 sr.DOI: 10.1111/j.1600-0889.2011.00556.x

Aerosol Robotic Network (AERONET) Sun photometer observations were carried out at Ouarzazate, Morocco, during the Saharan Mineral Dust Experiment (SAMUM) 2006. Data from one measurement day, 19 May 2006, are used to derive particle optical and microphysical parameters with AERONET's latest version of lightâ��scattering model for nonâ��spherical particle geometry. In our analysis we also make use of a novel measurement channel at 1638 nm wavelength. We compare the results to data products obtained by airborne highâ��spectralâ��resolution lidar, several groundâ��based Raman lidar, and airborne and groundâ��based in situ measurement platforms. We chose that specific measurement day because the dust plume was vertically well mixed. Extinction coefficients from AERONET Sun photometer and lidar observations and in situ measurements agree well. ��ngstr�¶m exponents from Sun photometer and lidar are in close agreement, too. Airborne in situ measurements of dust particle size distributions show larger effective radii than inferred from the AERONET data. Complex refractive indices that are derived with the AERONET algorithm differ from the values obtained with different independent techniques employed in our study. The singleâ��scattering albedo was derived from the airborne observations of particle size distributions and complex refractive indices. Singleâ��scattering albedo differs to the value inferred from the AERONET data. The differences may be attributed to the different effective radii that we obtained from the various techniques. The differences between the data products from the various measurement platforms, however, cannot be generalized, as we could only test data for one measurement day. An analysis of additional measurements is under way.