Volker Dreiling

Intercomparison of eleven condensation nucleus counters

*Universifiit Mainz, Saarstr. 21, 6500 Mainz, F.R.G. tDefense Technology and Procurement Group, NC Laboratory, 3700 Spiez, Switzerland :~ Universit~t Duisburg, Bismarckstr. 81, 4100 Duisburg !, F.R.G. § Deutscher Wetterdienst, Frahmredder 95, 2000 Hamburg 65, F.R.G. IINetherlands Energy Research Foundation, Postbus 1, 1755 ZG Petten, The Netherlands ¶ Nuclear Physics Laboratory, Proeftuinstraat 86, 9000 Ghent, Belgium ** Gesellschaft fiir Strahlenund Umweltforschung, PauI-Ehrlichstr. 20, 6000 Frankfurt, F.R.G. l t Luwa AG, Kanalstr. 5, 8152 Glattbrugg, Switzerland :~:~TSI GmbH, Schmiedstr. 3, 5100 Aachen, F.R.G.

Spatial distribution of the arctic haze aerosol size distribution in western and eastern Arctic

Abstract Since June 1993, four flight campaigns to the Arctic have been carried out by a group of scientists from Russia and Germany. Optical remote-sensing methods and in-situ chemical and aerosol measurements have been combined on board a Russian IL-18 research aircraft. From arctic air bases in Siberia, Alaska, Canada, and Spitsbergen, respectively, flights have been undertaken to determine spatial structure of arctic haze events. This paper reports on aerosol data obtained during the expedition of Spring 1994. Haze events have been found in the east and west Arctic, containing about the same concentration of particles. Horizontal and vertical layer extensions are given and the size distribution of number and surface is estimated from integral parameters.

Measurements of atmospheric condensation nuclei size distributions in Siberia

Abstract The least investigated atmospheric aerosol is the one in remote continental areas. In this study, measurements of condensation nuclei size distributions near Lake Baikal, Siberia, were performed. Data for total aerosol number concentration and aerosol size distribution were obtained. The measurement equipment consisted of a TSI screen diffusion battery (SDB) Model 3040 and a TSI condensational nuclei counter (CNC) Model 3020. The average aerosol number concentration was about 104 cm−3. The evolution of aerosol number concentration during the day is correlated with the solar radiation. The inversion problem was solved using Tihonovs regularisation procedure. The possibility of applying this algorithm was tested in computer simulations. Different forms of aerosol size distributions were observed. The maximum radius of the distributions changes from 10 nm to about 100 nm. The data obtained are in agreement with existing theories. It is planned to continue the measurements in the next years to obtain further results.

RAPID CONDENSATIONAL GROWTH OF PARTICLES IN THE INLET OF PARTICLE SIZING INSTRUMENTS

Abstract Rapid particle growth by the condensation of water vapour resulting from expansion in the inlet of particle sizing instruments such as optical particle counters and impactors was modelled. The corrected Mason diffusion growth equation extended to the application for particles beyond the continuum region has been found suitable. The influence of particle acceleration in the nozzle air flow, modelled with the CFX-FLOW3D program, on the condensation process was considered. The study was focused on a typical inlet nozzle of an optical particle counter with an inner diameter of 0.5 mm and a length of 20 mm, connected by an additional 20 mm long conical nozzle at a flow rate of 28.5 ml s −1 . The results show that particles smaller than 1.0 μ m can grow quickly during the very short-time passage through the nozzle as the saturation in the nozzle flow can increase several times. For particles with an initial radius of 0.15 μ m, i.e. the typical minimum detectable size of many commercial optical particle sizing instruments, condensational growth will cause a size increase up to 7% in the viewing volume. The whole particle size distribution will shift to larger radii, which results in an overestimate of both particle size and number in measurements. This condensational over-numbering and sizing effect should be given concern in evaluating measurement results as well as in aerosol instrument design.

Adaptation of microphysical and chemical instrumentation to the airborne measuring platform Iljushin I1-18 ‘Cyclone’ and flight regime planning during the Arctic Haze investigation 1993–1995

Abstract In 1993 the joint Russian-German Research Project ‘Arctic Haze’ started (see the Introduction and editorial note of this issue, by Jaenicke, Khattatov, Jaeschke and Leiterer). Besides CAO, four German groups were involved. To the present three airborne measuring campaigns have been performed. In total 251 h of flight within altitudes up to 8.7 km were flown in the western and eastern part of the arctic leading to a comprehensive set of data of the northern arctic hemisphere. The measurements were conducted aboard the Russian research aircraft I1-18 ‘Cyclone’ which was used by CAO in numerous scientific projects mainly in the former USSR. This 4 engined turboprop aircraft is well equipped with sensitive thermodynamical, optical and radiometric instrumentation. In consideration of the estimated aspects of ‘Arctic Haze’ additional microphysical, optical, and chemical instrumentation was adapted to the research aircraft. For co-ordinated measurements a detailed flight regime was planned taking into account the special requirements of the groups involved in the project. Main parts of the measurements were performed in box flights designed to get representative information of the investigated area. This allows the comparison of results gained in individual boxes at different locations or at different seasons. This contribution describes the basic equipment of the Russian research aircraft IL-18 as well as the adaptation of the special instrumentation for the ‘Arctic Haze’ investigations.

Time series of the condensation nuclei concentration at the german neumayer-station in antarctica since 1982

Publisher Summary The CN measurements are carried out at an air chemistry container separated from the main building to the south. So local contamination is avoided for most of the time. The concentrations are measured continuously. The data in Antarctica show a pronounced seasonality with the minimum in winter and a maximum in summer time. Earlier reports showed a significant increase of the concentration of 9.63 % per year during the years 1982 to 1989. The average concentration was 350 cm -3 . The new evaluation for the period 1990 to 1994 again showed an increase. However, because of communication problems, only the observations during winter time could be used. If the winter data of the complete period 1982 to 1994 are approximated with an exponential model, an increase of 5.8 % per year is observed. Such an increase over so many years is alarming, even if the reasons are not yet unveiled.