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The HALO Submicrometer Aerosol Inlet (HASI) was specifically designed for HALO with the aim to provide up to 30 l/min sample air flow (divided over four forward facing sample lines) to aerosol instruments mounted inside the aircraft cabin. HASI samples the air on the top of the fuselage outside of the aircraft boundary layer. The air stream is aligned in the inlet and deaccelerated in three stages by roughly a factor of 40 using a front shroud, a main diffusor and smaller diffusers at the tips of four sample tubes which protrude into the deaccelerated air stream. In addition, there is a backward-facing sample tube installed for optional use. The design concept is to allow regulating the sample air flow in each of the four forward-facing sample lines to achieve isokinetic sampling conditions according to the actual speed of the aircraft. Pumps and bypass lines for regulation of the air flow are part of the Aerosol Measurement System (AMETYST) cabin rack on HALO operated by DLR. The geometric design of the inlet should prevent large cloud droplets and ice crystals from entering the sample lines directly. Judging from the first measurements of different instruments using HASI during the ML-CIRRUS and ACRIDICON-CHUVA missions with HALO, it appears that condensation particle counter (CPC) measurements of interstitial aerosol in liquid clouds are affected by artefacts while in ice clouds there is no indication of any measurement problem. Selected examples of other measurement results for initial experimental characterization of the inlet will be discussed. In order to achieve better isokinetic sampling, further numerical flow simulations of the final inlet design for different aircraft altitudes and speeds are required to establish a final regulation of the sample air flow in each of the four sample lines based on pressure and temperature sensors in the inlet and aircraft data.

This work presents the characterisation of the Aerosol Package for the European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System). Condensation particle counter (CPC) are used to measure the aerosol number concentration of the total and the non-volatile particles. The size distribution is measured by means of an optical particle counter (OPC) in the diameter range of 0.25–3 µm. In particular the OPC is characterised for (1) leakage, (2) flow and calibration stability over the expected IAGOS pressure range of 170 hPa to 1013 hPa, (3) OPC accuracy test by comparing extinction measurements with calculated values from Mie theory using the OPC size distribution and (4) the inter-instrumental precision. The CPC is characterised in the same pressure range for (1) the lower cut-off diameter, (2) the instrument accuracy by comparing with a reference instrument (Faraday Cup Electrometer, FCE) and (3) the instrument precision. We conclude that the IAGOS Aerosol Package is a fully automated, robust, low-maintenance instrument providing high precision measurements with good accuracy.Keywords: IAGOS, aerosol, instrumentation(Published: 28 December 2015)Citation: Tellus B 2015, 67, 28339, http://dx.doi.org/10.3402/tellusb.v67.28339

During three recent field campaigns aerosol properties have been measured by the DLR airborne high spectral resolution lidar (HSRL) and an extensive set of aerosol in-situ probing instruments. SAMUM-1 (Saharan Mineral Dust Experiment, Morocco, 2006) aimed at the characterization of physical, chemical and radiative properties of African mineral dust. SAMUM-2 (Cape Verde Islands, 2008) focused on the observation of aged Sahelian dust and biomass burning aerosol from the African tropical regions. EUCAARI-LONGREX (European integrated project on Aerosol Cloud Climate and Air Quality Interactions, Long-range experiment, 2008) was conducted as a joint project to investigate the physical and chemical properties of aerosols on a European scale. The comprehensive data sets obtained through-out these field experiments contain information about some of the most prominent atmospheric aerosol types: Mineral dust aerosol, sea salt aerosol, biomass burning aerosol, continental background aerosol, and urban pollution aerosol. During all campaigns the DLR HSRL was operated aboard the Falcon research aircraft together with the in-situ probing instruments. The HSRL measured aerosol optical quantities at λ = 532 nm such as the aerosol backscatter coefficient, aerosol extinction coefficient, aerosol optical depth, the lidar-ratio and aerosol depolarization-ratio. By means of coordinated in-situ soundings, aerosol number size distribution, aerosol absorption, and aerosol volatility analyses have been performed. The sampling strategy during the field experiments generally consisted of two parts: Firstly, remote sounding at high altitude to observe and identify interesting aerosol layers by HSRL and then in-situ sounding within the layers at several flight levels defined by lidar before. Based on the HSRL measurements two aerosol-specific quantities the lidar-ratio and the depolarization-ratio, respectively, are derived. The analyses of both quantities reveal that characteristic values can be attributed to the different aerosol types. Capabilities and limitations of this classification are analysed using the coordinated in-situ data for each aerosol type. Therefore, variations of the in-situ measured aerosol properties are compared to the HSRL derived quantities. We will highlight the capability of the HSRL to classify different aerosol types and show synergy effects of the coordinated in-situ measurements.

Technical description of the NCO-P station in Himalayas

The presented work focuses on the experimental investigation of atmospheric aerosols of various origins. Main objectives are the characterisation of aerosols and their impact on climate. The first key topic is the effect of ageing and dilution of forest fire aerosol layers during long-range transport from the U.S. to Europe and the transformation of anthropogenic aerosols from urban pollution during atmospheric transport. For that purpose, observations from airborne measurements onboard the Falcon research-aircraft during the ITOP (Intercontinental Transport of Ozone and Precursors) field experiment in July 2004 are being analysed. The second key topic is the investigation of microphysical, optical and radiative properties of desert dust aerosols over source regions, as well as the modification of these dust properties during atmospheric transport from the source region to the far field and mixing with biomass burning aerosols. Information on these properties of aerosols are very important for satellite validation purposes (ENVISAT, ESSP 3/CALIPSO), for meso- and global-scale models and essential for the assessment of the impact of desert dust on climate. The information on the effects of transformation and mixing processes during long-range transport is urgently needed for an assessment of the impact of desert dust on the composition of the tropospheric aerosol and on heterogeneous chemical processes. To this aim, airborne in-situ measurements of desert dust aerosols in the vertical column over a source region and during long-range transport will be carried out during the German SAMUM (SAharan Mineral dUst experiMent) project.