Rapid condensational growth of aerosol particle in air stream — numerical simulation

Primary biological aerosol particles in the atmosphere: a review

Atmospheric aerosol particles of biological origin are a very diverse group of biological materials and structures, including microorganisms, dispersal units, fragments and excretions of biological organisms. In recent years, the impact of biological aerosol particles on atmospheric processes has been studied with increasing intensity, and a wealth of new information and insights has been gained. This review outlines the current knowledge on major categories of primary biological aerosol particles (PBAP): bacteria and archaea, fungal spores and fragments, pollen, viruses, algae and cyanobacteria, biological crusts and lichens and others like plant or animal fragments and detritus. We give a…

Application Of Microholography for Ground-based In Situ Measurements in Stratus Cloud Layers: A Case Study

Abstract A holographic droplet and aerosol recording system (HODAR) has been designed and operated in situ in a low-level stratus cloud layer adopting the Fraunhofer in-line technique to measure sizes and velocity vectors of cloud droplets as well as to determine sizes and shapes of other hydrometeors (e.g., graupel). The particle-size radii covered by this ground-based instrument range from three to several hundred micrometers. A case study conducted on the Kleiner Feldberg Mountain Observatory near Frankfurt, Germany, during November 1990 documents the temporal evolution of the cloud-droplet size distribution over a period of 19 h during which the size distribution changed from monomodal …

A method to identify biological aerosol particles with radius > 0.3μmfor the determination of their size distribution

Abstract The relevance of biological aerosol will be demonstrated. A method to determine the sizedistribution of the biological aerosols is shown, which gives the opportunity to determine a lower limit of the biological particles. For evaluation a light microscope and a scanning electron microscope equipped with an energy dispersive x-ray spectrometer are used.

Development of a Bioaerosol single particle detector (BIO IN) for the Fast Ice Nucleus CHamber FINCH

Abstract. In this work we present the setup and first tests of our new BIO IN detector. This detector was constructed to classify atmospheric ice nuclei (IN) for their biological content. It is designed to be coupled to the Fast Ice Nucleus CHamber FINCH. If one particle acts as an ice nucleus, it will be at least partly covered with ice at the end of the development section of the FINCH chamber. The device combines an auto-fluorescence detector and a circular depolarization detector for simultaneous detection of biological material and discrimination between water droplets, ice crystals and non activated large aerosol particles. The excitation of biological material with UV light and analy…

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 eq…

Condensation nuclei at the German Antarctic Station “Georg von Neumayer”

Evaluations of measurements of the tropospheric surface condensation nuclei at the German Antarctic station for the last 8 years are presented. They show clearly the annual variation of the concentration with a maximum in austral summer, as previously seen by other investigators. In addition, a pronounced increase of the concentration of 9.63% per year has been found. The size distributions of the condensation nuclei of measurements over 2 years are evaluated and discussed. On average, they are of mono-modal shape, but individually most of them show a bimodal shape. DOI: 10.1034/j.1600-0889.1992.00009.x

The processing of water vapor and aerosols by atmospheric clouds, a global estimate

Recent data published in literature on global cloudiness and precipitation as well as data on updrafts in clouds and their liquid water contents allow us to estimate the global turnover of water vapor and liquid water in the atmosphere. From these turnover rates the global average capacity of clouds to uptake, store and release atmospheric aerosol mass and the rate of wet deposition on the ground was estimated. The results of such an estimate suggest that clouds contribute significantly to the processing of aerosol material in the atmosphere as they constitute an important temporary storage location for it. Although the contribution of aerosol mass resulting from a single evaporation of the…

Comments on an article of Slinn

The discussion of the relationship between concentration fluctuations and residence times is certainly highly welcomed, because it can spread the news of how a simple analytical equation eases the often needed estimate of residence times for trace substances, gases and aerosols in size ranges. However, the treatment by Slinn (1988a) might confuse potential users. To ease the following clarification, I will use Slinn’s notation with C being a concentration and C the mean concentration, whether averaged over the exponentially decaying concentration in time or in distance downwind of a finite-area source. DOI: 10.1111/j.1600-0889.1989.tb00142.x

Oxygen isotopes in single micrometer-sized quartz grains: tracing the source of Saharan dust over long-distance atmospheric transport

Abstract Oxygen isotope compositions were measured by ion microprobe in individual micrometer-sized quartz grains extracted from one aerosol sample collected on the Cape Verde Islands and from four surface samples (three soils and one sediment) representing potential source regions of aerosols in Western and Central Africa (Morocco, Algeria, Niger, and Chad). A large range of δ18O values, from +6.2‰ to +39.3‰ is present within the aerosol quartz grains. The different size fractions of the quartz grains from the surface samples overlap nearly entirely this range but show significant differences in their δ18O distributions for the different size fractions of the grains (i.e., different modes,…

Microbiology and atmospheric processes: research challenges concerning the impact of airborne micro-organisms on the atmosphere and climate

 Cet article a fait l'objet d'une discussion dans "Morris, C. E., Sands, D. C., Bardin, M., Jaenicke, R., Vogel, B., Leyronas, C., Ariya, P. A., and Psenner, R.: Microbiology and atmospheric processes: an upcoming era of research on bio-meteorology, Biogeosciences Discuss., 5, 191-212, doi:10.5194/bgd-5-191-2008, 2008."; International audience; For the past 200 years, the field of aerobiology has explored the abundance, diversity, survival and transport of micro-organisms in the atmosphere. Micro-organisms have been explored as passive and severely stressed riders of atmospheric transport systems. Recently, an interest in the active roles of these micro-organisms has emerged along with prop…

The size distribution of primary biological aerosol particles in cloud water on the mountain Kleiner Feldberg/Taunus (FRG)

During the field campaign, FELDEX 95 cloud water samples were collected and the insoluble particles were analysed by single particle analysis in order to determine the content of primary biological aerosol particles (PBAP). It is found that 25% of the total insoluble particles are biological ones. During cloud events with increasing wind velocity, the concentration of biological particles also increases. Anthropogenic influence leads to a higher amount of both total and biological particles. Within the size distribution, the percentage of biological particles decreases with increasing radius.

Introduction and Survey

Hidden information within series of measurements ? four examples from atmospheric science

Whether in classical networks such as meteorological networks of in more recent ones of atmospheric chemistry, a wealth of data is at hand. These data have been evaluated in a manner depending on the purpose of the network. However, much more information is hidden in these time series and waits for discovery. Only the imagination of scientists is needed. Four examples are given which lead to new information about the atmospheric aerosol and the behaviour of the atmosphere. These examples are: “Atmospheric turbidity from sunshine recordings”, “Meteorological drainage area from the variance of observations”, “Location of point sources from air mass trajectories”, and “Total vertical ozone fro…

In-line holography of cloud volumes applied to the measurement of raindrops and snowflakes

Abstract The ground-based HODAR (HOlographic Droplet and Aerosol Recording) of the University of Mainz has been operational since 1989 on the Kleiner Feldberg Mountain Observatory near Frankfurt/Main, Germany, in a `small volume' configuration. With this setup an air volume of approximately 1 l can be in situ recorded, which allows it to image all aerosol particles and droplets with diameter larger than 6 μm contained in the sample volume in situ. Recently the beam diameter and optical path length of the inline system have been enlarged such that large cloud volumes (approximately 500 l) can be recorded on single holograms. During the holographic image reconstruction step in the laboratory,…

Holographic in-situ measurements of the spatial droplet distribution in stratiform clouds

Ground based in-situ measurements on the small-scale structure of low-level stratiform clouds have been performed utilizing the HOlographic Droplet and Aerosol Recording system (HODAR) of the University of Mainz, Germany. 6 holograms recorded during stratus cloud events on the Kleiner Feldberg Taunus Mountain Observatory (Frankfurt, Germany) were reconstructed in the laboratory and analysed by means of an automated data extraction and image processing system. In post-processing, each originally recorded droplet population was subjected to 2 statistical methods: (1) the sub-cell scanning analyses with statistical “Fishing” tests and (2) measurements of inter-droplet distance frequency distri…

New sunphotometer for network operation.

A handheld sunphotometer has been developed and is described. It operates for 9 wavelengths in the visible and near infrared. The sensitivity range is rather broad, so it can be used in turbid as well as clear atmospheres. The operation is simple, and a digital readout helps prevent operator biases. The instrument is sun powered and suitable for network operations. Determination of the atmospheric turbidity due to aerosol and the column content of O3, NO2, H2O is possible.

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 Tihonov's regularisation procedure. The possibility of appl…

Condensation nuclei measurements at theGeorg von Neumayer-Station (F.R.G.), Coastal Antarctica

The analysis of nearly continuous records of surface-based atmospheric condensation nucleiconcentration (CNC) since 1984 up to the present at the Georg von Neumayer-Station (GvN) shows clearly: u - an annual cycle of CNC with low values in winter time; - a significantly increasing frequency of CNC of more than 1000 particles per cm3 over the years.

Solar radiation extinction, sky radiation, sky light polarization and aerosol particle total number and size distribution on the Island Maui (Hawaii)

During April 1964 and from August through September 1965 measurements have been performed on the Maui Island, Hawaii. The results can be summarized as follows: a) the spectral extinction coefficient has a diurnal variation. The greatest value is found during noon. Its wavelength dependency shows an ‘anomalous extinction’, the maximum of extinction is to be found at 0.55 μ (Figures 1–3). b) the spectral radiance distribution of the total sky indicates the tendency that the aerosol size distribution does not follow a continuous power law. The exponent for small particles seems to bev*1 μ (Figure 8). d) the distribution of spectral degree of sky light polarization shows two maxima of polarizat…

Abundance of cellular material and proteins in the atmosphere.

Suspended atmospheric particles play a crucial role in any global climate scenario: They can both enforce and suppress radiative forcing. In developing climate modeling further, a deeper understanding of atmospheric aerosol is needed. Because of extreme local and temporal variations, proper incorporation of aerosols into models requires modeling of the aerosol itself. It turns out that cellular material and proteins compose up to 25% of the atmospheric aerosol. Consequently, the source strength of the biogenic aerosol in general must be corrected and should be estimated on the order of other major aerosol sources.

Perspectives on aerosol deposition to natural surfaces: interactions between aerosol residence times, removal processes, the biosphere and global environmental change

Abstract This paper summarizes the state-of-the-art and the research needs in the areas of aerosol residence-time assessments, deposition modelling, and understanding of aerosols in biogeochemistry. Research needs are emphasized from a systems perspective of global environmental change. Although fundamental quantitative knowledge is lacking, some qualitative linkages between source strengths, residence times, removal processes and the biosphere can be identified. It turns out that not only are the respective areas as such challenged by new problems, superimposed on the fairly well established conventional ones, but these areas also face mutually operating sets of feedbacks between residence…

Instrument intercomparison study on cloud droplet size distribution measurements: Holography vs. laser optical particle counter

During the EUROTRAC Ground Based Cloud Experiment (GCE) 1990, a newly developed HODAR (Holographic Droplet and Aerosol Recording) was operated for the first time to measure cloud droplet size distributions by recording Fraunhofer in-line holograms of small cloud sample volumes in situ and analyzing the holographic images in the laboratory.

In-Situ Measurements of the Cloud Microphysical Structure Using Holography

The ice nucleating ability of pollen

Abstract Laboratory experiments are described where the water uptake by a variety of pollen was studied quantitatively, followed by the investigation of the ice nucleating ability of four kinds of pollen in the deposition and the condensation freezing modes. The diameters of the pollen selected for the freezing experiments were between 25 and 70 μm. The freezing experiments in the deposition mode including also pollen resuspended from decayed leaves, and crushed pollen grains were carried out at different temperatures down to −33 °C combined with various supersaturations with respect to ice up to 35%. The condensation freezing experiments were carried out at temperatures down to −18 °C at s…

Size distribution, mass concentration, chemical and mineralogical composition and derived optical parameters of the boundary layer aerosol at Tinfou, Morocco, during SAMUM 2006

During the SAMUM 2006 field campaign in southern Morocco, physical and chemical properties of desert aerosols were measured. Mass concentrations ranging from 30 Ã�¼g m-3 for PM2.5 under desert background conditions up to 300,000 Ã�¼g m-3 for total suspended particles (TSP) during moderate dust storms were measured. TSP dust concentrations are correlated with the local wind speed, whereas PM10 and PM2.5 concentrations are determined by advection from distant sources. Size distributions were measured for particles between 20 nm and 500 Ã�¼m diameter (parameterizations are given). Two major regimes of the size spectrum can be distinguished. Smaller than 500 nm particle diameter, the distrib…

The ice nucleating ability of pollen:

Abstract Laboratory tests were conducted of the ice nucleating ability of four kinds of pollen in the immersion and the contact freezing modes. The diameters of the selected pollen were between 25 and 70 μm. The experiments were carried out at the Mainz vertical wind tunnel with freely suspended supercooled droplets at temperatures down to −28 °C. The immersion freezing experiments were conducted with drops of radii between 250 and 375 μm formed from distilled water with a defined amount of pollen added. The drops were freely floated in the wind tunnel while being supercooled. For the contact freezing experiments, a short burst of pollen was allowed to collide with freely suspended, superco…

The Primary Biological Aerosol in a Multiphase System

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…