MAP (Marine Aerosol Production)

Workplan

RTD_WP 1 Seasonal quantification of marine aerosol physico-chemical and biological characteristics (12 months). Maria Cristina Facchini
Task 1.1 Determination of the size-segregated chemical composition and aerosol microphysics during 1-year measurements at North Atlantic (Mace Head) and Mediterranean (Finokalia) marine stations.
Task 1.2 Analysis of the biogenic and anthropogenic organic components of the aerosol at Mace Head and Finokalia.
Task 1.3 Continuous measurements of halogen oxides and nucleation bursts at Mace Head.

RTD_WP 2 Quantification of marine aerosol production and evolution over N Atlantic plankton bloom (4 week NE Atlantic ship campaign). Thorsten Hoffmann
Task 2.1 Sea surface layer characterisation of surfactants and primary and secondary aerosol precursors
Task 2.2 Gas phase measurements of aerosol precursors
Task 2.3 Physical aerosol characterisation and flux measurements
Task 2.4 Chemical and biological aerosol characterization

RTD_WP 3 Identification, Quantification, and Parameterisation of Key Processes (Process Modelling). Gordon McFiggans
Task 3.1 Nucleation modelling.
Task 3.2 Aerosol Dynamics, Formation and Growth.
Task 3.3 Halogen cycling through marine aerosol
Task 3.4 Cloud activation modelling

RTD_WP 4 Development of S3F and organo-iodine source function. Gerrit de Leeuw
Task 4.1 Laboratory studies into the role of ozone in generating organo-iodine volatiles in sea-water and their sea-to-air transfer as a source of secondary aerosol precursors.
Task 4.2 Laboratory studies on bubble-mediated PMA formation as a function of surfactant concentration and bubble spectra.
Task 4.3 Evaluation and compilation of most appropriate satellite products for use in global source functions.
Task 4.4 Parameterization of S3F and CH2I2 source function.

RTD_WP 5 Large-scale modelling of marine aerosol impacts on atmospheric chemistry and radiative budget. Frank Dentener
Task 5.1 Inclusion of most recent aerosol parameterizations in CTM/RCM
Task 5.2 Implementation of SF and iodocarbon emissions in CTM/RCM
Task 5.3 Anthropogenic Primary aerosol emissions
Task 5.4 Impacts of marine aerosol (MAP simulation period)

Table 3. RTD Work Package and Task List.

 

7.4.1 RTD_WP1 - Seasonality
Seasonal quantification of marine aerosol physico-chemical and biological characteristics - Lead Partner CNR-ISAC

Overview: This WP will deliver a data base of the physical, chemical and biological characteristics of marine aerosol which will contribute to the achievement of the general objectives of the project and in particular, to Objectives 1 & 2. Results from WP1 will be used in many different activities, for example, in the methodological approach used in WP2, for elucidation of the main processes in WP3 and WP4, and for initialization and validation of large-scale models in WP5. WP1 will develop a multifaceted strategy of sampling and analytical methodologies for one year long continuous observation of the main aerosol physico-chemical and biological characteristics at two stations, representative for the main European marine environments - the North Atlantic (Mace Head Station, IE) and Mediterranean (Finokalia, GR)

• To quantify the main size-resolved physical and chemical properties of aerosol at two marine environments, North Atlantic and Mediterranean, following the seasonal pattern under distinct clean/anthropogenic conditions
• To investigate the dependence of natural marine aerosol properties on the seasonal biological cycle in North Atlantic and Mediterranean
• To identify and quantify specific chemical, bio-chemical and biological tracers of organic matter sea-air transfer.
• To elucidate the role of biogenic IO in driving new particle production and their temporal distribution.
• To develop new chemical, biochemical and biological methods for identification and quantification of specific markers involved in PMA production.

Description of the work

Task 1.1 (Obj 1 & 2) Determination of the size-segregated chemical composition and aerosol microphysics during 1-year measurements at North Atlantic (Mace Head) and Mediterranean (Finokalia) marine stations. (JRC, ISAC, NUIG, UoC, JGUM)

The seasonal trends in the size-segregated chemistry and microphysics and hygroscopic properties of marine aerosol will be followed during one year of observations at two stations in the marine boundary layer: Mace Head (IR, 54ºN, 9ºW) and Finokalia (Crete, GR, N35°, E25°). The trends in aerosol OC at the two sites will be evaluated in terms of seasonal variation in biological activity in the North Atlantic and in the Mediterranean, provided from satellite derived chlorophyll concentration (in collaboration with WP4). Possible anthropogenic influence from in-situ sources (ship tracks), transport from distant pollution sources, influencing the observed levels of OC concentration, will be carefully discriminated using a sector controlled sampling strategy, air mass back trajectory analysis, satellite detection of ship tracks, and a post screening of “pollutants” markers.

Task 1.1.1 Physical measurements. An extensive suite of aerosol instrumentation will be operated at Mace Head, including CPCs, APS, SMPS and nano-SMPS to measure aerosol concentrations and size-distributions from the supermicron size range down to 3 nm. Atmospheric ion concentrations will be made using an AIS (Atmospheric Ion Spectrometer) in order to quantify any role of ions in coastal nucleation processes. Further, a potential modification of the instrument will be tested in terms of its ability as a neutral-cluster spectrometer to identify any potential source of seed clusters upon which nucleation may occur. Periodically, and on a seasonal basis, analysis of hygroscopic water uptake will be made using a combination of MOUDI impactor samples in a humidified chamber and through the use of a hygroscopic TDMA system. The aerosol samplers are complimented by measurements of aerosol scattering, aerosol absorption and aerosol optical dept. In Finokalia, a PM10, a PSAP, a Magee two-channel Aethalometer, a Radon counter and two nephelometers (one dry and the other at ambient RH) will be operated on a routine basis. NUIG, UoC, UHel

Task 1.1.2 Size-segregated chemistry. Mass-size distributions of the aerosol and of the main aerosol chemical components will be provided by cascade impactors, including ELPI, 8-stage and 5-stage Berner-LPI and a 12-stage SDI. The aerosol mass will be determined on coated aluminium foils with 6-digit microbalances in well defined conditions of relative humidity and temperature. Tedlar and quartz substrates will be also adopted allowing the determination of inorganic salts by ion chromatography, individual halogen compounds by elemental mass spectrometry, total WSOC by TOC analysis, OC/BC by TOT and TOR methods, as well as the mineral fraction by elemental analysis, thus providing the mass closure of the chemical species in size-segregated aerosols samples. The optical correction for TOT and TOR methods will be carefully evaluated for samples showing a high content of sea-salt, in order to provide a more accurate split between OC and BC. Sampling with the impactors will be continuous at Mace Head and semi-continuous at Finokalia. CNR-ISAC, UoC, JRC

Task 1.2 (Obj. 1 & 2) Analysis of the biogenic and anthropogenic organic components of the aerosol at Mace Head and Finokalia. (ISAC, JRC, UoC, UNIVPM, JGUM)
Specific chemical and biological methodologies focusing on organic aerosol will integrate the more general aerosol characterization implemented in Task 1.1. Task1.2 specifically aims to: A) Identify main patterns in the organic chemical composition, in terms of functional group and chemical classes, characteristic of the different regimes classified on the basis of the analysis of the back-trajectories (continental-influenced versus more clean conditions); B) Identify and quantify the aerosol primary organic components originated by biogenic sources at the sea surface by means of chemical isolation/identification methods and by specific nucleic acid-based technologies.

Task 1.2.1. Sampling for the analysis of organic compounds. High-volume samplers devoted to the analysis of organic aerosols will be deployed at Mace Head and Finokalia, and combined with denuders and back-up impregnated filters to minimize and quantify sampling artifacts. Currently used denuders and back-up filters will be tested and adapted to work well in a humid and sea-spray rich atmosphere and thus provide artifact-reduced sampling. JRC, UoC, CNR-ISAC

Task 1.2.2 Organic characterization. The aerosol samples collected at the two stations will be subjected to extensive chemical analysis, including NMR techniques for functional group analysis and hyphenated chromatographic techniques with multistage mass spectrometry, such as HPLC/[MS]3, for the advanced separation and structure identification of organic compounds and/or compound classes. In particular the insoluble/refractory fraction of the aerosol will be analyzed upon extraction with solvents of different polarity, acidic digestion, and after derivatisation and depolymerization steps. The analysis of the biological materials of marine origin (proteinaceous substances, sugars, lipids, and fulvic acids) will be systematically pursued by means of updated analytical methods developed for the dissolved and particulate matter in seawater. UoC, CNR-ISAC

Task 1.2.3 Analysis of the biological markers. The extraction and quantification of microbial DNA from the samples collected at Mace Head and Finokalia will be performed according to newly developed analytical protocols, aiming to identify highly specific markers of marine biological sources in the aerosol samples. The 16S rRNA genes of microbial components will be amplified using highly specific primers able to selectively amplify the RNA of prokaryotes at genus or species level. This will allow gathering a quantitative information on the contribution of cellular and extra-cellular components to the aerosol particles. A more comprehensive description is given in Task 2.4.3. UNIVPM

Task 1.3 (Obj. 1) Continuous measurements of halogen oxides and nucleation bursts at Mace Head. (UoH, NUIG, UHel)

Task 1.3.1 Continuous measurement of nucleation bursts The suite of instruments used in Task 1.1.1 will contribute to the seasonal quantification of ion concentration, neutral cluster concentrations, 3 nm particle concentration and source rate, aerosol growth rates and aerosol condensation and coagulation sinks. The nucleation events, their duration and intensity will be analysed in conjunction with the seasonally measurements of IO concentration at Mace Head. NUIG, UoH, UHel.

Task 1.3.2 Continuous measurements of halogen oxides A long term program of simultaneous particle and halogen oxide, in particular iodine oxide, observations will allow to asses the inter-relationship between the two aerosol and gas species in terms of seasonality of the North Atlantic biological cycle. The long term measurement of halogen oxides (BrO, IO, OIO), related trace gases (NO2, formaldehyde, and I2) and aerosol optical density will be performed with passive Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS). This novel technique , which is already well proven in a series of applications, allows the quantification of atmospheric trace gas distributions in the lower troposphere from the spectral absorption structures of the gases superimposed on the solar radiation reaching the surface. Due to its passive operation the instrument hardware (but not the software) is relatively robust and lends itself to unattended operation. Since sunlight is used measurements can only be made during daylight hours. Only then, however, photochemical activity and noticeable IO levels are expected. In additional to the passive DOAS measurements, active DOAS measurements, using an artificial light source, will be conducted in parallel for a 2-3 week period in order to provide a quantification of the longer-term passive measurement accuracy. UoH

7.4.2 RTD_WP2 - Intensive Observing Period (High Biological Signal)
Quantification of marine aerosol production and evolution over North Atlantic plankton bloom (6 week IOP NE Atlantic ship campaign).
Lead Partner JGUM

Overview. The goal of this WP is to characterise the physical, chemical and biological processes leading to the production of open-ocean marine aerosols during the period of maximum biological activity (IOP), and thus, to quantify the maximum biogenic influence on marine aerosol. The focus is on both SMA and PMA systems. The most comprehensive suite of on-line and off-line instruments and analytical procedures will be deployed in this WP to:
• Characterise the sea-surface layer in terms of organics, surfactants and iodine precursors
• Quantify the relative importance of iodine, sulphur and organic gases to new particle formation
• Provide a characterisation of aerosol physics, boundary layer meteorology and PMA size-segregated fluxes
• Provide a chemical and biological-component analysis of marine aerosols and tracing to specific biological species.
The main experimental component is a 4-week IOP ship-borne campaign over the North Atlantic, the specific location will be determined by the most productive area seen via SeaWifs ocean colour products. Since the location of the campaign will be to the west of Mace Head, connected flow experiments will also be conducted. Some of the on-line aerosol chemistry analysers (aerosol mass spectrometers) will be deployed on a short (3 week) winter campaign at Mace Head to provide a winter (low biological activity period) contrast to the peak bloom signal in the summer. The results of the campaign will help to elucidate the dominant condensable vapours driving SMA formation and new particle production. Likewise, the collected data will assist in the quantification of the number and size flux of primary inorganic and organic sea-spray aerosol. Therefore, WP contributes to Objectives 1 & 2 of the overall project.

Description of the work
Task 2.1 (Obj. 1 & 2) Sea surface layer characterisation of surfactants and primary and secondary aerosol precursors (UoY, JGUM, UEA, CNR-ISAC, UNIVPM, SU)

Task 2.1.1 Organohalogens - A range of volatile organohalogens (CHCl3, CH3I, C2H5I, 1- and 2-C3H7I, CH2ClI, CH2BrI, CH2I2, CHIBr2, CH2Br2, CHBr2Cl, and CHBr3) will be measured using two Perkin Elmer Turbomass GC-MS systems with automated preconcentration/thermal desorption devices. One will be dedicated to air (see Task 2.2.2) and the other to seawater measurements, the latter by purge and trap. Both systems will be calibrated using an in-house calibration system ensuring consistency of the air and water measurements – UoY.
Task 2.1.2 Iodide/iodate concentrations, which can be used as an indicator of the biogenic iodine chemistry in near-surface seawater and at the same time might play an essential role in the release of elemental iodine from the sea into the atmosphere, will be measured in the surface water during the ship campaign. This will be done based on the separation of iodide and iodate using an anion exchanger followed by ICP/MS measurements – JGUM.
Task 2.1.3 Surfactants & chemical and biological markers - Surfactant-rich surface seawater samples will be collected during the ship campaign, filtered and stored cool and in the dark prior during shipping from the field to the laboratory. In the laboratory the surfactant concentrations in the samples will be determined applying a polarographic method based on a dropping mercury electrode. UEA. Besides the measurements of the overall surfactant concentration, the surface water samples will be further characterized using a set of methodologies that are also applied to the aerosol samples (see WP1 and Task 2.4): this will allow to identify common features (surfactants, chemical and biological markers) to elucidate the sea surface-aerosol transfer of organic matter. Particular attention will be devoted to the chemical characterization of the water-soluble and insoluble organic constituents and the related surface tension properties: the main analytical tool will be the combination of chromatographic and NMR techniques and surface tension measurements. A newly developed analytical protocol based on amplification of microbial DNA (see WP1 and Task 2.4.3) will be applied to quantitatively identify highly specific markers of marine biological sources in the surface water – CNR-ISAC, UNIVPM.

Task 2.2 (Obj. 1) Gas phase measurements of aerosol precursors (MPI-K, UoY, JGUM, UHEI.IP)
Task 2.2.1 Sulphur species. Measurements of atmospheric gaseous aerosol precursors will be made during the ship-cruise in the Atlantic marine boundary layer. Using a CIMS (Chemical Ionization Mass Spectrometry) apparatus equipped with an ion-trap mass spectrometer (ITMS) the atmospheric aerosol precursor trace gases H2SO4, MSA and SO2 will be measured online during the campaign. Using the ITCIMS apparatus high-quality quantitative measurements of very low atmospheric H2SO4 and SO2 concentrations can be realized. DMS will also be measured using GC-MS techniques.– MPI-K, UoY.
Task 2.2.2 Organohalogens The same set of volatile organohalogens (CHCl3, CH3I, C2H5I, 1- and 2-C3H7I, CH2ClI, CH2BrI, CH2I2, CHIBr2, CH2Br2, CHBr2Cl, and CHBr3) which will be measured in surface water samples (Task 2.1.1) will also be quantified in the air during the campaign. Again, a GC-MS technique will be applied for the organohalogen measurements. - UoY.
Task 2.2.3 Molecular iodine The gas phase concentration of molecular iodine will be measured during the MAP ship campaign. Two different techniques will be used for this purpose, a denuder-based selective sampling technique for molecular iodine (starch-coated denuders) followed by ICP/MS measurements and by a spectroscopic technique (MAX-DOAS see also Task 1.3.2 and 2.2.4). Since both techniques possess different features in terms of detection limit as well as temporal (e.g. MAX-DOAS is restricted to daylight hours) and spatial resolution, the application of two independent methods not only improves the reliability of the produced results, but also will deliver complementary information about the molecular iodine concentration over the open ocean during the campaign. – JGUM, UHEI.IP.
Task 2.2.4 Halogen oxides Passive Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) will also be used for the measurement of halogen oxides (BrO, IO, OIO) on board the research ship. In addition, the mass spectrometric online technique described above (CIMS, Task 2.2.1) will be further developed for the detection of BrO and IO; however, this development is a parallel and independent activity to MAP and is contributed free-gratis. This CIMS mode will be operational during the ship campaign. Again, parallel measurements with two independent analytical techniques, which are based on completely different measurement principles, will be advantageous for the reliability and usability of the results – UHEI.IP, MPI-K.

Task 2.2.5 Volatile organic compounds Using a second Chemical Ionisation Mass Spectrometer (CIMS) equipped with a linear quadrupole, volatile organic compounds (VOC) will also be measured onboard the research vessel during the campaign – MPI-K.

Task 2.3 (Obj. 2 & 3) Physical aerosol characterisation and flux measurements (UHel, MPI-K, UKU, SU)

Task 2.3.1 Air ion measurements An Air Ion Spectrometer (AIS) will measure the mobility distribution of air ions (naturally charged clusters and aerosol particles) in the range of 0.00075-2.4 cm2 V-1s-1. The mobility distribution will be presented by 28 logarithmically uniformly distributed fractions: 12 fractions in the mobility range of 0.075-2.4 cm2 V-1s-1 and 16 fractions (two fractions per electrometrical channel) in the range of 0.00075-0.075 cm2 V-1s-1. The corresponding diameter range is 0.46 and 55 nm. These measurements will be accompanied by mass spectrometric measurements of atmospheric ions using the same instrument which is used in Task 2.2.5 in a separate operation mode (ion mass spectrometer mode of operation) - MPI-K, UHel.

Task 2.3.2 Particle size distribution A Twin Differential Mobility Particle Sizer (twin-DMPS-system) will be utilized to obtain sub-micron aerosol particle size distributions. The time resolution is typically 10 minutes in which time aerosol from 3 nm up to 1000 nm in diameter is classified. In addition, supermicron aerosol size distributions will be measured with an Aerodynamic Particle Sizer (APS-3320, TSI Inc, USA). This instrument extends the measurement range up to approximately 10 ?m. The APS uses aerodynamic size as a basis of the classification whereas the DMPS applies the electrical mobility equivalent diameter. Using both datasets also an estimate of particle density in the accumulation mode sizes will be gained – UHel.

Task 2.3.3 Hygroscopicity & CCN measurements Hygroscopic Tandem Differential Mobility Analyser (HTDMA) can be utilized to tentatively identify the particle composition. During the MAP ship campaign the hygroscopic growth factor (HGF) of selected nucleation, Aitken and accumulation mode sizes will be measured. Simultaneously, the CCN concentrations at different supersaturations will be measured using a CCN chamber (Droplet Measurement Technologies). Closure studies will be carried out by relating the growth factors to CCN concentrations through Köhler theory and cloud modelling. These instruments will be deployed for the short winter campaign at Mace Head. – UHel, UKU.

Task 2.3.4 Aerosol flux measurements A new technique for measurements of aerosol fluxes for particles of different size and volatility will be further developed and applied during the campaign. The method is based on the combination of eddy correlation and aerosol volatility measurements and results in information about the size resolved aerosol number flux for particles of different volatility. The idea behind these measurements is the separation and quantification of the contribution and distribution of sea salt and volatile or semi-volatile organic compounds, which are key data for the development and validation of the new marine aerosol source parameterizations. Total aerosol fluxes will be measured using a fast response CPC and size segregated fluxes will be measured using a range of (Particle Measurement Systems) optical particle counters. Associated micro-meteorology characterizations will necessarily come with the aerosol flux results. Fluxes will be analysed in terms of wind speed/friction velocity and white-cap coverage to evaluate the best meteorological parameter to relate to PMA fluxes. Similarly, fluxes will be evaluated in terms of surface water chemistry – SU.

Task 2.4 (Obj. 2) Chemical and biological aerosol characterization (UNIVPM, CNR-ISAC, UoC, JGUM, JRC, UMAN, UKU)
The general information on main soluble and insoluble chemical components of aerosol as a function of size will be obtained following the same sampling and analytical strategy as described in WP1 (Task 1.1). Particular effort will be devoted to the characterization of natural primary and secondary organic aerosol components linked to phytoplankton activity employing different and complimentary chemical, biochemical and biological methodologies:

Task 2.4.1 OC/BC measurements OC and BC will be analyzed from impactor substrates and back-up filters using both optical reflectance and transmittance correction. A thermal method will be specially develop to enable the accurate split OC/BC in presence of large amount of sea salt, using standard mixture of sea salt, organic species (e.g. sucrose, levoglucosan), elemental carbon, and spiking the new NIST OC/EC standard with relevant amount of sea-salt – JRC.

Task 2.4.2 Functional group analysis A combination of chromatographic and NMR techniques will be employed to characterise soluble and insoluble organic components. Specific efforts will be dedicated to the extension of the aerosol organic analysis, currently limited to the water-soluble fraction, to the insoluble OC extractable in appropriate solvents or after acidic digestion. The analytical methods will be calibrated with suitable standards of proteins, carbohydrates, lipids and humic substances and with biological substances isolated from surface water and surface microlayer samples collected during the ship campaign – CNR-ISAC.
In order to receive further size segregated information about the chemical composition of aerosol particles, fractions of the samples will be derivatised followed by reductive cleavage, depolymerization and quantitative 31P-NMR spectroscopy to detect and quantify the most important polar organic functional groups (e.g. carboxylic, hydroxyl groups) – UoC.

Task 2.4.3 Biological and biochemical components A new method for the extraction and quantification of DNA from aerosol (and surface water micro-layers - Task 2.1) has been developed. A molecular validation of the extracted DNA will be performed using nucleic-acid based technologies. The molecular approach will be based on the extraction and purification of DNA from surface waters and aerosol and the subsequent amplification of 16S rRNA genes of microbial components (prokaryotes), using highly specific primers able to selectively amplify the 16S rDNA at genus or species level (for both heterotrophic and photoautotrophic prokayotes). This will allow gathering not only quantitative information on the contribution of cellular and extra-cellular components to the aerosol particles, but also to obtain a fingerprint of their marine origin. In fact, it is known that aerosol might contain a variable abundance of viruses and bacteria and preliminary aerosol samples from Mace Head indeed reveal the presence of viruses and bacteria, but up to now we have had no way to prove the exact origin of these microorganisms. The availability of new molecular tools will allow for the first time to identify the origin of these biological particles – UNIVPM.

Task 2.4.4 Speciation of single components For the advanced compound separation and structure identification of marker compounds (especially natural and anthropogenic surfactants) hyphenated chromatographic techniques with multistage mass spectrometry, such as HPLC/MS/MS, will be applied to the size-segregated aerosol samples. The results of the individual organic species analysis will be especially helpful for the interpretation of the outcome of Tasks 2.4.1 and 2.4.2. In addition, the same inorganic species which will be measured in the sea surface water (Task 2.1.2) will also be measured in the particle phase. The analytical protocol for the speciation of individual iodine compounds in submicron particles (I-, IO3-, IxOy) is based on size-segregated sampling (Berner-impactor) followed by an aqueous extraction step. While the higher iodine oxides (e.g. I2O4) possess a very low water solubility, iodide and iodate ions are readily extracted from the impaction media. The two soluble ions are separated using an anion exchanger-technique. Finally the iodine concentration of all three fractions can be measured by ICP/MS – UoC, JGUM.

Task 2.4.5 Aerosol mass spectrometry Several mass spectrometric online systems will work in parallel during the ship campaign. The two conceptually different, currently available real-time mass spectrometric concepts – laser desorption/ionisation single particle mass spectrometry (here the SPASS system (Single Particle Analysis and Sizing System)) and thermal evaporation electron impact mass spectrometry (here two Aerodyne AMS systems (one quadrupole and one time-of-flight system)) – will be used. Both techniques deliver highly time-resolved size-segregated information about the chemical composition of aerosol particles. The SPASS system is especially valuable to measure metals like Na, Ca, Fe, Al, Zn, Cu, Ni, Pb as well as halogens in single particles in the size range between 50 nm and 3 ?m. However, also information about the sulfate, nitrate and carbon content can be obtained, although their quantification is problematic. In addition, SPASS provides important information about internal and external mixing of the particles. In parallel, one of the two Aerodyne AMS systems will be used onboard the ship and the other 50% at Mace Head for connected flow experiments. The AMS system is better suited to get quantitative information about the different aerosol fractions (i.e. organic, sulfate, halogens). However, utilizing the time-of-flight version of the AMS also the internal mixing state of sulphate, sea-salt and organic material is accessible and allows a search for evidence for chloride and organic correlation in single particles. Finally, the aerosol mass spectrometric results will be compared with impactor data and therefore will provide greatly improved temporal and size resolution onto which the impactor analyses may be mapped. In particular mass spectral fingerprints of the organic fraction can be compared with organic functionality analyses. The Aerodyne AMS will be deployed at Mace Head for the Winter campaign. – JRC, UMAN, UKU.

7.4.3 RTD_WP3 – Aerosol Process Modelling

Identification, Quantification, and Parameterisation of Key Processes (Process Modelling) - Lead Partner UMAN

Overview. Based on the current state-of-the-art, WP3 integrates the findings from WP1 and WP2 to develop realistic process descriptions and accurate parameterisations of the key processes determining the formation and transformation of SMAs. The work package will feed descriptions of the following processes to the large scale models in WP5:

• Coastal and open ocean aerosol nucleation (Objective 1),
• Aerosol dynamics and growth (Objective 1) in the marine environment,
• Heterogeneous chemistry and multiphase processes including halogen cycling through marine aerosol (Objective 4),
• The effect of organic components of marine aerosol on cloud droplet activation (Objective 4).

The underpinning hypothesis is that marine aerosols may have a significant effect on climate change. This effect critically depends on the size and composition distribution of aerosol particles. Over the past decade, the formation and growth of nanometer-size atmospheric aerosol particles have been observed at a number of sites around the world from a variety of platforms over a range of time periods. A review of all existing particle formation data from literature has recently been made concluding that the formation rate of 3-nm particles is often in the range 0.01-10 cm-3 s-1 in the boundary layer. However, formation rates as high as 104-105 cm-3 s-1 have been observed in coastal areas. Measurements during nucleation episodes of evolving size distributions down to 3 nm can be used to calculate the apparent source rate of 3-nm particles and the particle growth rate; this technique has been used to deduce that typical mid latitudes growth rates are in the range 1-20 nm hour-1 depending on the temperature and the availability of condensable vapours. Because nucleation can lead to a significant increase in the number concentration of cloud condensation nuclei, and this increase is critically dependent on the aerosol dynamics and growth, global climate models will require reliable models for nucleation, aerosol dynamics and cloud activation. In both sub- and supersaturated regimes, the evolving aerosols may provide a medium for surface and condensed phase reactions. A range of heterogeneous processes affecting the oxidative budget in the marine environment have been reported. Therefore, to describe the regional and global ozone and sulphur budgets, for example, it is necessary for large-scale models to contain accurate parameterisations of these processes. Constrained and informed by the measurements from WP1 and WP2, a range of detailed process models will be employed to develop a standalone aerosol module and a range of individual process parameterisations for WP5.

Description of the work

Task 3.1 (Obj. 1) Nucleation modelling (UMAN, UHel)

Task 3.1.1 The primary goal of the first task is to quantify the nucleation rate of new particles in both coastal and open ocean conditions. Predictions of sulphate TSC formation rate and viable iodine oxide clusters formation will be made based upon vapour source strength measured during the field projects (WP1 and WP2). To investigate and quantify the relative contributions to viable particle formation in a variety of marine environments, a variety of methodologies will be used to investigate whether condensation of higher iodine oxides onto sulphate TSCs is a viable mechanism for their stabilisation against coagulation loss. This will involve the use of a full range of detailed theoretical modelling approaches exploring the stabilisation and formation of viable aerosol. The possible considerations of the growth process include heterogeneous nucleation of organic insoluble vapours on existing clusters (either sulphate, iodide or ion clusters); activation of the clusters for condensation of soluble organic/inorganic vapours i.e. nano-Köhler theory (a process analogous to activation of cloud droplets); and the multicomponent condensation of organic and inorganic vapours. The growth rates will be calculated in atmospheric conditions and compared with those measured to confirm the participating mechanisms. (UMAN, UHel)

Task 3.2 (Obj. 1) – Aerosol Dynamics, Formation and Growth (FMI, UHel)

The main goal of this task is to develop an upgraded multi-component and externally mixed aerosol dynamical module suitable for the RCM model in WP5.1 and to provide component upgrades to the M7 module used in the TM5 CTM.
Task 3.2.1 Sectional aerosol module. Development of a suitable sectional aerosol size distribution representation. It will satisfy the following criteria: 1) allow a computationally efficient treatment of aerosol dynamical processes, 2) cover the whole size range relevant to secondary and PMA production, 3) able to treat both internal and external aerosol mixtures, and 4) easily incorporated into a three-dimensional model framework. FMI
.
Task 3.2.2 Formation Rate Accurate parameterisation of secondary aerosol formation. Detailed treatment of all the processes involved in secondary aerosol formation is not possible in large-scale models. The parameterisation needs nucleation rate, condensable vapour concentrations and pre-existing aerosol size distribution as input. As output it will provide a formation rate of particles at any size desired by the host aerosol dynamical module, decreasing the number of size sections needed in the large scale simulations. FMI

Task 3.2.3 Aerosol Growth Development of an accurate treatment of aerosol growth by the condensation of H2SO4, CIVs, and organic vapours present in the marine atmosphere, including a description of heat and mass transfer as well as thermodynamics of these compounds. FMI, UHel

Task 3.2.4 Design for CTM/RCM Building of interfaces with other large-scale model components. The aerosol dynamical module will interact with 1) the host meteorological model, 2) the gas-phase chemistry model, and 3) the existing cloud modules. FMI

Task 3.3 (Obj. 4) Halogen cycling through marine aerosol (UC, UMAN)

Task 3.3.1 Halogen cycling The main aim of this task is to draw on the aerosol and halocarbon precursor field measurements WP1 and WP2 to drive two box models of reactive halogen chemistry. A previously reported UMAN model, extended to include explicit aerosol microphysics, thermodynamics and full aqueous halogen chemistry and a box model (UoC) that contains VOC and DMS chemistry together with detailed halogen (Cl, Br and I) chemistry will be compared and used to i) make standalone predictions of the effects of halogens on the oxidative chemistry (ozone destruction, HOx and NOx speciation), ii) determine the critical chemical reactions related to halogen chemistry and ozone and aerosol budgets and iii) to develop a fully linked nitrogen, halogen, sulphur and VOC scheme for incorporation in the CTM used in WP5.3. For i) both models will use the most recent kinetic data based on the EU_FP5 THALOZ project.

Task 3.4 (Obj.4 ) Cloud activation modelling (NUIG, UKU, UMAN, ISAC)

Task 3.4.2 Thermodynamics and Surface Tension. The four aerosol-cloud process models use a range of thermodynamic treatments ranging from Pitzer molality-based ion interaction treatment extended to include small organic ions to a multicomponent inorganic/organic treatment using the Pitzer-Simonsen-Clegg mole fraction model combined with UNIFAC modified to be applicable to atmospherically representative compounds. The models will be evaluated to determine which is the most appropriate thermodynamic module capable of dealing with inorganic-organic mixed aerosols. Field measurements of aerosol chemical composition and surface tension from WP1 and WP2 will be used to develop thermodynamic models for water activity and surface tension with different degrees of complexity. The models also include a variety of treatments of the surface tension effects ranging from a semi-empirical relationship with bulk organic concentration, through a parameterised but thermodynamically consistent description of multicomponent surface excess to an explicit treatment of a separate surface phase. Dynamic surface tension measurements will be used in order to estimate whether the effects are relevant during cloud droplet activation and growth. If necessary, the dynamic surface tension will be explicitly treated in the cloud microphysics models. Measurements of equilibrium and dynamic surface tension for marine aerosol and standard organic compounds will provide the data to develop and test surface tension models which describe equilibrium and kinetic behaviour of mixed atmospheric surfactant solutions. By inclusion of a fully characterised sub-micron organic aerosol fraction, the range of models will explore the warm cloud activation of multicomponent aerosols. This activity will be conduced in conjunction with the ACCENT NoE Aerosol sub-project. (NUIG, UKU, UMAN, ISAC)

Task 3.4.1 Parameterisation of Aerosol-Cloud Activation. Once the best way to handle mixed inorganic-organic thermodynamics and surface tension effects has been identified, the models will be used to develop aerosol-cloud activation schemes based on multi-component sulphate, sea-spray, and organic aerosols in the presence of nitric acid and ammonia. (UKU, CNR-ISAC, UMAN)

Task 3.4.3 In-cloud sulphate production. Given that most of the production of aerosol sulphate relates to in-cloud aqueous phase processes, which in turn, is dependent on the sea-spray, nitric acid and organic acid concentrations, a parameterisation will be developed to quantification in-cloud sulphate production for use in the large scale models. The model will provide an extensive treatment of heat and mass flux treatments, activation and aqueous phase sulphate production. (NUIG)

7.4.4 RTD_WP4 - GEOSS Products

Development of PMA and organo-iodine sea-to-air transfer schemes - Lead partner TNO-FEL

Overview WP4 will integrate results from WP1 and WP2 with laboratory results, focusing on sea-air exchange of PMA and iodo-carbon gases, and global meteorological and oceanic satellite products to produce:

• An improved S3F source function (including inorganic and organic fractions)parameterized in terms of sustained satellite observations (Objective 2)
• A global data set for the production of PMA which can be assimilated into large-scale models; (Objective 3, 4)
• A first exploratory attempt to develop a global data set for the production of organo-iodine gases (Objective 3,4).

The sea-air transfer of PMA (defined as aerosol directly produced by the interaction between wind and waves, containing inorganic sea salt and organic material in a variable ratio) and gases is driven by near-surface oceanic and atmospheric processes such as wave breaking and turbulence. The description of the relevant processes in terms of parameters which are available from satellite observations, such as wave height, wind speed, sea surface temperature, chlorophyll and whitecap cover, will provide a tool to directly determine the fluxes of PMA and aerosol precursor gases on a global scale. Coupling satellite observations to these parameterizations provides the most feasible mechanism for inclusion of PMA and SMA precursor source strengths into global and regional models. The output of WP4 feeds directly into WP5 in terms of provision of source functions into the model simulations. Satellites used to provide data have an operational character and hence the data can be transferred to data product providers in the framework of GMES projects (such as GEMS and GSE PROMOTE) and thus contribute to the establishment of the European component to GEOSS through GMES. Through this WP, MAP will also provide the marine aerosol research and development component for the GMES Integrated Project GEMS, thus contributing to the establishment of the European component to GEOSS.

Description of the work

Task 4.1 (Obj. 3) - (UEA, TNO)
Laboratory studies into the role of ozone in generating organo-iodine volatiles in sea-water and their sea-to-air transfer as a source of secondary aerosol precursors.

Task 4.1.1 Ozone produced organo-iodine. The interaction between ozone and inorganic I species will be studied in the laboratory by exposing natural and iodide-containing artificial seawater to a stream of ozonised air and the concentrations of iodide and VIOCs in the water and of ozone and VIOCs in the air will be monitored as function of time. Seawater will be used that has been previously tested for its capability of producing VIOCs upon additions of I2/HOI. The influence of the concentration and composition of natural DOM in the formation of VIOCs will be studied by carrying out additions of I2/HOI to freshly-collected seawater from the MAP intensive campaign. During the cruise, also deck-board incubations will be carried out with natural phytoplankton assemblages in order to assess if production of VIOCs via the I2/HOI pathway is enhanced by DOM produced by phytoplankton during different stages of growth. UEA.

Task 4.1.2 Bubble-mediated CH2I2 transfer. (Characterisation of the role of bubbles and surfactants on sea-air transfer of CH2I2). The experiments of Task 4.1.1 will be repeated in the presence of artificially generated bubbles using aerators and/or a weir and bubble spectra will be measured with an optical bubble measuring system. Different bubble concentrations will be generated. Surfactant will be added in different concentrations and characterised and concentrations of CH2I2 in water and in air will be measured. Results will be parameterized to provide a first estimate of the transfer rate of CH2I2. UEA

Task 4.2 (Obj. 2 and 3) - (SU, TNO, UNIVPM, ISAC)
Laboratory studies on bubble-mediated PMA formation as a function of surfactant concentration and bubble spectra.

Task 4.2.1 Bubble-mediated aerosol production – LAB. This task will build on experiments of bubble-mediated production of sea spray aerosol in artificial (inorganic) sea water which focused on aerosol production as a function of water temperatures and salinity and preliminary experiments on the influence of synthetic surfactant concentration on particle micro-physics. The above studies will be extended to cover a more detailed temperature range (2-22oC), more realistic bubble spectra and different natural and synthetic surfactant concentrations. SU, TNO.

Task 4.2.2 Bubble-mediated aerosol production – FIELD The experiments in Task 4.3.1 will be located during the intensive field campaign to conduct similar experiments under actual conditions during the peak bloom activity without disturbing the biological evolution of dissolved organic matter and surfactants. These experiments will compliment the simultaneous in-situ flux measurements during the campaign and filter samples of produced PMA will be analysed for their organic content utilising methods described in WP1, including biological characterization. These experiments will be particularly important during the cruise because the risk of changing the physical, chemical and especially biological properties of the sea-water will be minimal when the experiments are conducted on fresh sea water. SU, TNO, UNIVPM, CNR-ISAC.

Task 4.3 (Obj. 3) - (TNO, NUIG)
Evaluation and compilation of most appropriate satellite products for use in global source functions.

Task 4.3.1 Satellite Product Evaluation. Evaluation of most current satellite products for quantifying sea-surface characteristics relevant to the sea-air exchange of aerosols and gases will be conducted. Wave height and wind speed will be obtained from radar instruments (e.g., ENVISAT’s ASAR, RA-2, QUIKSCAT), whitecap cover will be determined using SSM/I and AVHRR, sea surface temperature from AATSR (ENVISAT) and chlorophyll from SeaWifs. The usefulness of these satellite products for determination of fluxes of PMA and organo-iodine will be evaluated. Long-term availability of the instruments will be a consideration for utilisation in developing operational systems (e.g. GEMS) and to contribute to GEOSS. Emphasis will also be on instruments such as SAR and AATSR, which are planned to be launched as part of the ESA Earthwatch mission. TNO, NUIG

Task 4.3.2. Satellite Product Preparation The selected data products from Task 4.4.1 will be compiled and prepared for the MAP modelling period (Year 2002-2005). Interfaces between the satellite products and the CTM and RCM will be produced to ensure the smooth integration of the satellite derived products into these models. TNO, NUIG.

Task 4.4 (Obj. 2 & 3) - (TNO, SU, NUIG)
Parameterization of PMA source function and CH2I2 sea-air transfer.

Task 4.4.1 S3F GEO Product In-situ measurements from WP1 and 2 will be combined with laboratory measurements of Task 4.2 to develop a parameterization in terms of the key satellite products which will be provided to the large scale models. The focus will be to provide accurate parameterisations of whitecap cover, temperature and surface organic matter concentration which will be combined with the bubble-mediated source function per unit whitecap cover from the laboratory experiments (Task 4.2). Comparison of the result with the direct eddy-covariance measurements and resulting parameterisations serves to analyse the influence of various processes, i.e. bubble-mediated production versus spume droplet production as function of wind speed and particle size. Results from the chemical analyses will also play a key role in this effort. TNO, NUIG, SU.

Task 4.4.2 CH2I2 GEO Product Key results on the sea-air transfer of CH2I2 and of bubble-mediated transfer from field and laboratory studies will be incorporated, along with satellite biological and meteorological fields, into producing a GEO product for incorporating large scale emissions of CH2I2 into regional and global climate models. TNO, UEA

7.4.5 RTD_WP5 – Global & Regional impacts of Marine Aerosols

Large Scale Modelling of Marine Aerosol and it’s Impacts - Lead Partner JRC
Overview.
WP5 integrates the information obtained in WP1-WP4, in the form of parameterisations of key processes relating to PMA and SMA formation, into large scale atmospheric chemistry and climate models and to quantify the impact of primary and SMAs on atmospheric chemistry, radiative forcing and climate. WP5 will focus on:

• Implementing state-of-the-art knowledge on marine aerosol inclusion into large scale models
• Integrating GEOSS products into predictive CTM and RCM global/regional models
• Quantifying the relative contribution of primary and secondary, and natural and anthropogenic, marine aerosols to the marine aerosol annual budget.
• Quantifying the interaction between marine aerosols and oxidants and its influence on marine atmospheric chemistry.
• Quantifying the impact of marine aerosols on the direct and indirect radiative budget.
• Quantifying the impact of marine aerosols on regional climate.

The developed parameterisations will be implemented and tested in two different state-of-the-art models: the global-regional scale off-line chemistry transport model TM5 and the regional climate model RCM. The focal years for simulations will be 2003-2005, further we will assess the years 2000 (for which much measurement information is available in the context of AEROCOM). Further a regional focus will be over the Western European/North Atlantic Region and the Mediterranean region. The two models considered are the off-line global TM5 model, with a 1x1 two-way nested zoom over Europe and the regional climate model RCA3 (based on HIRLAM). Model characteristics are given in Table 5.

Table 5: large scale model characteristics
Model Resolution Domain Type-Meteo Gas Chemistry Aerosol chemistry-physics Specific application-remarks
RCA v.3 0.4°x0.4° 19- 31L Europe- incl. European Russia Regional, HIRLAM Prescribed oxidant fields Bulk- to be replaced by bin scheme Operational forecast- aerosol cloud interaction
TM5 4°x6°,2°x3°,1°x°1°, 25L Global, European zoom:
10°W-40°E 35°N-70°N Global to regional; ECWMF CBM4 Modal M7, EQUISAM-ISORROPIA Consistent global-regional scale interactions. Interface science-policy.

Description of the work .
Task 5.1 (Obj. 4) Inclusion of most recent aerosol parameterizations in CTM/RCM (NUIG, JRC, UoC)
Task 5.1.1 Nucleation Iodine-Sulphur nucleation parameterizations will be implemented in both the CTM and RCM. Initially, both models will implement and utilize current parameterizations of TSC nucleation and as the parameterization of coupled TSC-iodine nucleation is developed, it will be implemented and evaluated. NUIG, JRC
Task 5.1.2 Aerosol Dynamics The aerosol dynamics module developed in WP3 will be implemented in the RCA and will be evaluated in terms of performance with respect to the M7 module in the CTM. The module will be compared for a few case studies with the established M7 aerosol dynamic module, used in TM5. At the start of MAP, we will implement a hybrid aerosol dynamic into RCM to allow for externally-mixed aerosol populations. This version will be replaced by the update module developed in WP3.2 JRC, NUIG
Task 5.1.3 Chemistry The heterogeneous Aerosol-Chemistry scheme currently used in TM5 will be upgraded to focus on SOA formation and halogen recycling in the marine environment. The current secondary organic aerosol formation scheme that is incorporated in the TM5 will be updated with the latest kinetic information tested using box model in WP3. Using this updated scheme we will evaluate the growth of aerosols from secondary reactions on aerosol surfaces. We will focus on SOA formation in marine environment resulting from multiphase production of carboxylic acids resulting from the oxidation of organic substances. JRC, UoC
Task 5.1.4 Cloud Activation A simplified parameterisation for cloud droplet activation and in cloud sulphate production as a function of organic matter, sea-salt, sulphate and nitrate content of aerosol developed in WP3 will be implemented and tested in RCM and CTM. NUIG, JRC

Task 5.2 Implementation of S3F and iodocarbon emissions in CTM/RCM (Obj. 3 & 4) (NUIG, UoC, JRC)
Task 5.2.1 GEO Products The GEOSS source functions developed in WP 4 will be implemented in the RCM and CTM to derive global sea-spray and CH2I2 emissions. The parameterisations developed and the global satellite datasets prepared will be coupled and tested using a number of case studies. They will be evaluated using sea-spray specific satellite A-ATSR retrievals and in-situ measurements.

Task 5.3 (Obj. 4) – Anthropogenic ship aerosol emissions (JRC).
Task 5.3.1 Ship Emissions In order to separate the respective roles of natural and anthropogenic emissions, emission inventories will be compiled for current and future shipping models and will be implemented to evaluate the contribution of anthropogenic versus natural/primary and secondary aerosol emissions (e.g. sulphates, soot carbon and organic carbon). Uncertainties in emission data will be evaluated, as will energy and economical emission scenarios to assess the future role of these emissions in the year 2030. We will explore the possibility to use concurrent SCIAMCHY/OMI NO2 measurements and MISR/MODIS aerosol optical thickness data to evaluate the model calculations with satellite data. JRC

Task 5.4 (Obj. 4) Aerosol Budgets and Impacts MAP simulation period. (UoC, JRC, NUIG)
With the upgraded parameterisations, GEOSS products, and ship emissions implemented in the large scale models, we will perform simulations using the RCM and TM5 for the period 2003-2005 and for the AEROCOM year of reference 2000. The simulations will be aimed at quantification of the impact of natural and anthropogenic sources of marine aerosols, including those from ship transport emissions.
Task 5.4.1 Annual Budgets Evaluation of the seasonal and annual regional and global aerosol budgets – focussing on the roles of primary/secondary, and natural/anthropogenic aerosol using TM5 and RCM. JRC, UoC, NUIG
Task 5.4.2 Atmospheric Chemistry Evaluation of the impact of heterogeneous reactions on aerosol production and growth. Specifically we will assess the roles reactions of nitrogen oxides, halogens with VOCs and DMS and SOA production using TM5. The effects of heterogeneous reactions on marine aerosols and their impacts on ozone and oxidants using TM5 will be quantified. UoC, JRC
Task 5.4.3 Radiative Forcing & Climate The direct radiative forcing effect from these aerosols will be evaluated with both the RCM and TM5. Particular focus will centre on the North Atlantic and the Mediterranean region. Similarly, indirect radiative forcing and impact of marine aerosols on climate over the North Atlantic and western Europe will be evaluated with RCM and an evaluation of the impact of marine aerosol on regional climate will be conducted. JRC, NUIG