The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne measurements was performed in the framework of the Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental setup also involved several ground-based measurement sites on islands including two ground-based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote-sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modeling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to producing high levels of atmospheric pollutants or intense biomass burning events in the region. However, numerous mineral dust plumes were observed during the campaign, with the main sources located in Morocco, Algeria and Tunisia, leading to aerosol optical depth (AOD) values ranging between 0.2 and 0.6 (at 440 nm) over the western and central Mediterranean basins. One important point of this experiment concerns the direct observations of aerosol extinction onboard the ATR-42, using the CAPS system, showing local maxima reaching up to 150 M m−1 within the dust plume. Non-negligible aerosol extinction (about 50 M m−1) has also been observed within the marine boundary layer (MBL). By combining the ATR-42 extinction coefficient observations with absorption and scattering measurements, we performed a complete optical closure revealing excellent agreement with estimated optical properties. This additional information on extinction properties has allowed calculation of the dust single scattering albedo (SSA) with a high level of confidence over the western Mediterranean. Our results show a moderate variability from 0.90 to 1.00 (at 530 nm) for all flights studied compared to that reported in the literature on this optical parameter. Our results underline also a relatively low difference in SSA with values derived near dust sources. In parallel, active remote-sensing observations from the surface and onboard the F-20 aircraft suggest a complex vertical structure of particles and distinct aerosol layers with sea spray and pollution located within the MBL, and mineral dust and/or aged North American smoke particles located above (up to 6–7 km in altitude). Aircraft and balloon-borne observations allow one to investigate the vertical structure of the aerosol size distribution showing particles characterized by a large size (> 10 µm in diameter) within dust plumes. In most of cases, a coarse mode characterized by an effective diameter ranging between 5 and 10 µm, has been detected above the MBL. In terms of shortwave (SW) direct forcing, in situ surface and aircraft observations have been merged and used as inputs in 1-D radiative transfer codes for calculating the aerosol direct radiative forcing (DRF). Results show significant surface SW instantaneous forcing (up to −90 W m−2 at noon). Aircraft observations provide also original estimates of the vertical structure of SW and LW radiative heating revealing significant instantaneous values of about 5° K per day in the solar spectrum (for a solar angle of 30°) within the dust layer. Associated 3-D modeling studies from regional climate (RCM) and chemistry transport (CTM) models indicate a relatively good agreement for simulated AOD compared with observations from the AERONET/PHOTONS network and satellite data, especially for long-range dust transport. Calculations of the 3-D SW (clear-sky) surface DRF indicate an average of about −10 to −20 W m−2 (for the whole period) over the Mediterranean Sea together with maxima (−50 W m−2) over northern Africa. The top of the atmosphere (TOA) DRF is shown to be highly variable within the domain, due to moderate absorbing properties of dust and changes in the surface albedo. Indeed, 3-D simulations indicate negative forcing over the Mediterranean Sea and Europe and positive forcing over northern Africa. Finally, a multi-year simulation, performed for the 2003 to 2009 period and including an ocean–atmosphere (O–A) coupling, underlines the impact of the aerosol direct radiative forcing on the sea surface temperature, O–A fluxes and the hydrological cycle over the Mediterranean.

This poster deals with vertical dependence of breakpoint occurrence at the European ozonosonde stations up to 30 km in the period 1979-2011.We used data from the following stations: Hoheipeissenberg, (Germany), Payerne (Switzerland), Uccle (Belgium), Lindenberg(Germany) and Legionowo (Poland). At each station and each season we computed 1–km wide height intervals of ozone concentration up to 30 km. We explore the statistical method for breakpoint searching and we are interested in the time position of breakpoints. We use one or two breakpoints in each height interval and season. We expect in the stratosphere the breakpoints will be situated about mid-90s and it will be very interesting to find the position of the second breakpoint A climatology of potential vorticity filaments and related exchange between the tropics and extratropics in the lower stratosphere A. Kunz, M. Sprenger, and H. Wernli Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland The global atmospheric re-analysis product ERA-Interim from the European Centre for Medium-Range Weather Forecasts is used to investigate lower stratospheric potential vorticity (PV) structures and exchange of air masses between the tropics and the extratropics from 1979 to 2011. A climatology of PV filaments and cutoffs above the subtropical jet stream is presented on isentropic surfaces from 350 to 500 K. The recently developed concept of the strongest isentropic gradients in the dynamical fields of PV and wind speed is applied to mark a dynamically relevant PV contour on every isentropic surface. An Eulerian algorithm is then used to identify filaments and cutoffs of this PV contour and a trajectory-based technique to study the exchange across this contour. The combination then allows quantifying the significance of the PV filaments and cutoffs for the isentropic exchange across this dynamically relevant boundary. The presented climatology extends already existing climatologies of cross-tropopause exchange connected with PV streamers into the lower stratosphere. This analysis is particularly relevant for the assessment of the chemical impact of the lower branch of the residual circulation. The climatology of PV filaments reveals a seasonal cycle with a higher frequency in summer than in winter in both hemispheres. During winter, intrusions are completely suppressed on isentropic surfaces above 400 K in line with the activity of the polar vortices. Global highest frequency of PV filaments is found between 380 and 440 K in northern hemispheric summer simultaneous with dynamics of the Asian anticyclone. In general, PV filaments in equatorward direction are more frequent than in poleward direction. The quantification of the mass fluxes associated with these PV structures identifies different atmospheric transport pathways between the tropics and extratropics with strong geographical variability. In the northern hemispheric summer, strongest PV filaments connected with severe exchange are preferentially located above the North Pacific. An atmospheric pathway is identified that transports air masses around the Asian anticyclone from northern toward southern Asia and the Indian ocean. In the southern hemispheric summer, highest frequency of PV filaments connected with severe air mass exchange is located above the South Pacific. This atmospheric pathway transports air masses from above the Indian ocean in eastward direction around the Antarctic toward the South Pacific. Brewer-Dobson circulation in the ERA-Interim: increase or decrease? B. Legras, M. Diallo Laboratoire de Météorologie Dynamique, IPSL, /CNRS/ENS/UPMC/Ecole Polytechnique, UMR 8539, Paris, France The Brewer-Dobson circulation in the ERA-Interim has been investigated with Lagrangian diabatic and kinematic trajectories and calculations of effective diffusivity. The calculated ages and the age spectrum show patterns which are very similar to those obtained in the GEOSCCM model. The best agreement with the observations, including in the polar regions, is obtained with diabatic trajectories after discarding all parcels travelling above 0,5 hPa. It is noticeable that kinematic versus diabatic age of air exhibits an old bias in the lower southern stratosphere below 25 km and a young bias in the mid northern stratosphere above 25 km. There is a trend in the ERA-Interim age of air which is negative in the lower stratosphere and positive above 25 km. This result is at odd with most CCM which predict an intensification of the whole Brewer-Dobson circulation. The residual circulation decreases in the ERA-Interim and is over compensated by an increased meridional mixing in the lower stratosphere. This suggests an opposite evolution of the shallow and deep branches of the Brewer-Dobson circulation. We will present more results investigating whether the ERA-Interim trend is due to biases in the observation system or the model, and comparing ERA-Interim with MERRA Stratospheric Aerosol over Lauder, New Zealand J. B. Liley, T. Sakai, T. Nagai, I. Morino, K. Nakamae, O. Uchino NIWA, Lauder, P O Box 50061, Omakau; MRI, Tsukuba, Ibaraki 305-0052, Japan; NIES, Tsukuba, Ibaraki 305-8506, Japan Lidar observations of the stratosphere and upper troposphere from Lauder (45° S, 170° E) have been made since November 1992. The data series to February 2009, using a single instrument to measure backscatter at 532 nm, provides a uniform data record from the Pinatubo aftermath through recent stratospheric aerosol change. The data correlate well with backscattersonde measurements and with SAGE data in the years to 2000. The upper tropospheric record shows an annual spring maximum attributable to tropical biomass burning. The stratospheric aerosol burden after the Pinatubo eruption declined with an efolding time of about 1.4 years, to a minimum integrated backscattering coefficient (IBC) of about 1.4 x 10-4 sr-1. In the decade to 2009, stratospheric IBC increased at a rate of around 4% per year. This trend correlates well with satellite observations. In February 2009 the Lauder aerosol lidar system was upgraded to a dual-wavelength (1064 and 532 nm system) that also measures depolarisation, similar to the CALIOP lidar system on the CALIPSO satellite. The upgraded Lauder system measures cirrus and tropospheric aerosol by day in support of ground-based near-IR FTS measurements for GOSAT validation, for which cloud and aerosol scattering is an important factor. The Lauder aerosol lidar was also used to characterise the aerosol from the June 2011 eruption of Puyehue-Cordón Caulle in Chile. In addition, the new lidar system continues the night-time stratospheric aerosol measurements for NDACC. Here, we report on the long-term observation of stratospheric aerosols over Lauder, the recent trend, and sensitivity to assumed air density profile and to the normalisation height. Global Dimming and Brightening in New Zealand

We have investigated the behaviour of light scattering by particulates of various sizes (0.1 μm to 100 μm) at a small scattering angle (below 20°). It has been previously shown that, for a small angle, the scattered intensities are weakly dependent upon the particulates' composition (Renard et al., 2010). Particles found in the atmosphere exhibit roughness that leads to large discrepancies with the classical Mie solution in terms of scattered intensities in the low angular set-up. This article focuses on building an effective theoretical tool to predict the behaviour of light scattering by real particulates at a small scattering angle. We present both the classical Mie theory and its adaptation to the case of rough particulates with a fairly simple roughness parameterisation. An experimental device was built, corresponding to the angular set-up of interest (low scattering angle and therefore low angular aperture). Measurements are presented that confirm the theoretical results with good agreement. It was found that differences between the classical Mie solution and actual measurements – especially for large particulates – can be attributed to the particulate roughness. It was also found that, in this low angular set-up, saturation of the scattered intensities occurs for relatively small values of the roughness parameter. This confirms the low variability in the scattered intensities observed for atmospheric particulates of different kinds. A direct interest of this study is a broadening of the dynamic range of optical counters: using a small angle of aperture for measurements allows greater dynamics in terms of particle size. Thus it allows a single device to observe a broad range of particle sizes whilst utilising the same electronics.

Remote sensing measurements of light scattered by dust in solar system objects can provide clues on their physical properties. Databases obtained in the laboratory with numerous samples are necessary to interpret these measurements. We present here first studies of the wavelength dependence of the linear polarization between 545nm and 1.5μm, using the imaging polarimeters PROGRA2 for large levitating compact grains (PROGRA2-VIS in the visible domain, and the new instrument PROGRA2-IR in the near infrared). The measurements are conducted in microgravity conditions during parabolic flights for glass beads, quartz, sands, silicon carbides, anthracite, and lunar and Martian simulants. Comparison between measurements on glass beads and Mie calculations with glass spheres provides an assessment of the quality of the instruments. The dependence of the polarization on the wavelength is related to the complex refractive index of the particles, i.e. to their composition and to the size of the grains. More laboratory measurements will be necessary, in particular with smaller grains in aggregates, to better reproduce the remote sensing observations of solar system bodies.

The purpose of this paper is to improve the design of an ultrasonic reactor for industrial applications in liquids, which consists of a double‐structured tank. This paper presents an experimental approach for studying ultrasonic transmission through an immersed glass plate. Several inclination angles, between 0 and 40 ∘ , and several thicknesses have been investigated. Acoustic efficiency was determined using hydrophone measurements in different places in the reactor. A first reactor prototype was built and the optimised configuration defined was experimentally partially characterized and validated.