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Two new submodels for the Modular Earth Submodel System (MESSy) were developed. The New Aerosol Nucleation submodel (NAN) includes new parameterisations of aerosol particle formation rates published in recent years. These parameterisations include ion-induced nucleation and nucleation of pure organic species. NAN calculates the rate of new particle formation based on the aforementioned parameterisations for aerosol submodels in the ECHAM/MESSy Atmospheric chemistry - Climate (EMAC) model. The Ion pair production rate, needed to calculate the ion-induced or -mediated nucleation, is described using the new submodel IONS, which provides ion pair production rates for other submodels within the MESSy framework. Both new submodels were tested in EMAC simulations. These simulations showed good agreement with ground based observations.

We present the in-situ biogeochemical data products distributed by the Copernicus Marine Service since 2018. The products offer available data of chlorophyll, oxygen, and nutrients (nitrate, silicate and phosphate), both in near-real time and as re-processed data, collected across the globe. The re-processing involves careful quality control utilizing tailored automated quality control procedures combined with visual inspection of questionable values by experts. Moreover, oxygen data are provided with uniform units for modelers (µmol/l) and other oceanic applications and monitoring purposes (µmol/kg) The products integrate observations aggregated from the Regional EuroGOOS consortium, as well as from SeaDataNet2, National Data Centers (NODCs) and JCOMM global systems, among others.We highlight some use cases, including a study showing an overall decline in the nutrient concentration (nitrate and silicate) of the Atlantic Water flowing though the Nordic Seas en-route to the Arctic Ocean, during the period 1990-2019. Moreover, the study shows indications of a delayed-response reduction further downstream in the Arctic Water exiting the Arctic Ocean through Fram Strait. Other use cases include the study of variability in the concentration of dissolved oxygen in the Mediterranean Sea, showing an association with dynamical processes.The in-situ near-real time biogeochemical product is updated every month whereas the re-processed product is updated two times per year. Products are delivered on NetCDF4 format compliant with the CF1.7 standard and well-documented quality control procedures.

The Copernicus Marine service is a “one-stop-shop” providing freely available operational data on the state of the marine environment for use by marine managers, advisors, and scientists, as well as intermediate and end users in marine businesses and operations. The Copernicus Marine service offers operationally updated and state-of-the-art products that are well documented and transparent. The European Commission’s long-term commitment to the Copernicus program offers long-term visibility and stability of the Copernicus Marine products. Furthermore, Copernicus Marine offers a dedicated service desk, in addition to training sessions and workshops.Here, we present the in situ biogeochemical data products distributed by the Copernicus Marine System since 2018. It offers available data of chlorophyll-a, oxygen, and nutrients collected across the globe. These products integrate observation aggregated from the Regional EuroGOOS consortium (Arctic-ROOS, BOOS, NOOS, IBI-ROOS, MONGOOS) and Black Sea GOOS as well as from SeaDataNet2 National Data Centers (NODCs) and JCOMM global systems (Argo, GOSUD, OceanSITES, GTSPP, DBCP) and the Global telecommunication system (GTS) used by the Met Offices.The in situ Near Real Time biogeochemical product is updated every month whereas the reprocessed product is updated two times per year. Products are delivered on NetCDF4 format compliant with the CF1.7 standard and well-documented quality control procedures.

We predict cyclohexane–water distribution coefficients (log D 7.4) for drug-like molecules taken from the SAMPL5 blind prediction challenge by the “embedded cluster reference interaction site model” (EC-RISM) integral equation theory. This task involves the coupled problem of predicting both partition coefficients (log P) of neutral species between the solvents and aqueous acidity constants (pK a) in order to account for a change of protonation states. The first issue is addressed by calibrating an EC-RISM-based model for solvation free energies derived from the “Minnesota Solvation Database” (MNSOL) for both water and cyclohexane utilizing a correction based on the partial molar volume, yielding a root mean square error (RMSE) of 2.4 kcal mol−1 for water and 0.8–0.9 kcal mol−1 for cyclohexane depending on the parametrization. The second one is treated by employing on one hand an empirical pK a model (MoKa) and, on the other hand, an EC-RISM-derived regression of published acidity constants (RMSE of 1.5 for a single model covering acids and bases). In total, at most 8 adjustable parameters are necessary (2–3 for each solvent and two for the pK a) for training solvation and acidity models. Applying the final models to the log D 7.4 dataset corresponds to evaluating an independent test set comprising other, composite observables, yielding, for different cyclohexane parametrizations, 2.0–2.1 for the RMSE with the first and 2.2–2.8 with the combined first and second SAMPL5 data set batches. Notably, a pure log P model (assuming neutral species only) performs statistically similarly for these particular compounds. The nature of the approximations and possible perspectives for future developments are discussed.

We present the results of laboratory measurements of the ion–ion recombination coefficient at different temperatures, relative humidities and concentrations of ozone and sulfur dioxide. The experiments were carried out using the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at CERN, the walls of which are made of conductive material, making it possible to measure small ions. We produced ions in the chamber using a 3.5 GeV c−1 beam of positively charged pions (π+) generated by the CERN Proton Synchrotron (PS). When the PS was switched off, galactic cosmic rays were the only ionization source in the chamber. The range of the ion production rate varied from 2 to 100 cm−3 s−1, covering the typical range of ionization throughout the troposphere. The temperature ranged from −55 to 20 °C, the relative humidity (RH) from 0 to 70 %, the SO2 concentration from 0 to 40 ppb, and the ozone concentration from 200 to 700 ppb. The best agreement of the retrieved ion–ion recombination coefficient with the commonly used literature value of 1.6 × 10−6 cm3 s−1 was found at a temperature of 5 °C and a RH of 40 % (1.5 ± 0.6) × 10−6 cm3 s−1. At 20 °C and 40 % RH, the retrieved ion–ion recombination coefficient was instead (2.3 ± 0.7) × 10−6 cm3 s−1. We observed no dependency of the ion–ion recombination coefficient on ozone concentration and a weak variation with sulfur dioxide concentration. However, we observed a more than fourfold increase in the ion–ion recombination coefficient with decreasing temperature. We compared our results with three different models and found an overall agreement for temperatures above 0 °C, but a disagreement at lower temperatures. We observed a strong increase in the recombination coefficient for decreasing relative humidities, which has not been reported previously.

Out of the Air New-particle formation from gaseous precursors in the atmosphere is a complex and poorly understood process with importance in atmospheric chemistry and climate. Laboratory studies have had trouble reproducing the particle formation rates that must occur in the natural world. Riccobono et al. (p. 717 ) used the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN to recreate a realistic atmospheric environment. Sulfuric acid and oxidized organic vapors in typical natural concentrations caused particle nucleation at similar rates to those observed in the lower atmosphere.

For atmospheric sulfuric acid (SA) concentrations the presence of dimethylamine (DMA) at mixing ratios of several parts per trillion by volume can explain observed boundary layer new particle formation rates. However, the concentration and molecular composition of the neutral (uncharged) clusters have not been reported so far due to the lack of suitable instrumentation. Here we report on experiments from the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research revealing the formation of neutral particles containing up to 14 SA and 16 DMA molecules, corresponding to a mobility diameter of about 2 nm, under atmospherically relevant conditions. These measurements bridge the gap between the molecular and particle perspectives of nucleation, revealing the fundamental processes involved in particle formation and growth. The neutral clusters are found to form at or close to the kinetic limit where particle formation is limited only by the collision rate of SA molecules. Even though the neutral particles are stable against evaporation from the SA dimer onward, the formation rates of particles at 1.7-nm size, which contain about 10 SA molecules, are up to 4 orders of magnitude smaller comparedwith those of the dimer due to coagulation and wall loss of particles before they reach 1.7 nm in diameter. This demonstrates that neither the atmospheric particle formation rate nor its dependence on SA can simply be interpreted in terms of cluster evaporation or the molecular composition of a critical nucleus., Main text plus SI

Here we explore the vapour pressure of sulphuric acid at very low relative humidity, where evaporation of sulphuric acid from particles can be important in the atmospheres of Earth and Venus. We performed experiments in the CLOUD chamber at CERN forming sulphuric acid particles via nucleation and then measuring evaporation versus temperature and relative humidity. We modelled the experiments with the ADCHAM model to constrain the thermodynamic properties governing the evaporation of sulphuric acid. ADCHAM includes a thermodynamics module coupled to an aerosol dynamics module. We derived the mole fractions and activity coefficients of H2SO4, HSO4−, SO42− and SO3 in the particles and then simulated the condensation and evaporation of H2SO4 and SO3. We constrained the equilibrium constants for the dissociation of H2SO4 to HSO4− (KH2SO4) and the dehydration of H2SO4 to SO3 (xKSO3). Our results suggest that particle shrinkage is mainly governed by H2SO4 evaporation, however, we cannot dismiss a contribution from SO3 evaporation. We conclude that KH2SO4 = 2–4 ∙ 109 mol ∙ kg−1 at 288.8 ± 5 K and xKSO3 ≥ 1.4 ∙ 1010.

We predict cyclohexane-water distribution coefficients (log D

Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood1. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours2. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere3,4, and that ions have a relatively minor role5. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded6,7. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.

New particle formation in the atmosphere produces around half of the cloud condensation nuclei that seed cloud droplets. Such particles have a pivotal role in determining the properties of clouds and the global radiation balance. Dunne et al. used the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN to construct a model of aerosol formation based on laboratory measured nucleation rates. They found that nearly all nucleation involves either ammonia or biogenic organic compounds. Furthermore in the present day atmosphere cosmic ray intensity cannot meaningfully affect climate via nucleation.Science this issue p. 1119Fundamental questions remain about the origin of newly formed atmospheric aerosol particles because data from laboratory measurements have been insufficient to build global models. In contrast gas phase chemistry models have been based on laboratory kinetics measurements for decades. We built a global model of aerosol formation by using extensive laboratory measurements of rates of nucleation involving sulfuric acid ammonia ions and organic compounds conducted in the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber. The simulations and a comparison with atmospheric observations show that nearly all nucleation throughout the present day atmosphere involves ammonia or biogenic organic compounds in addition to sulfuric acid. A considerable fraction of nucleation involves ions but the relatively weak dependence on ion concentrations indicates that for the processes studied variations in cosmic ray intensity do not appreciably affect climate through nucleation in the present day atmosphere.U http://science.sciencemag.org/content/sci/354/6316/1119.full.pdf

The accurate measurement of the gaseous sulfuric acid concentration is crucial within many fields of atmospheric science. Instruments utilizing chemical ionization mass spectrometry (CIMS) measuring H(2)SO(4), therefore, require a careful calibration. We have set up a calibration source that can provide a stable and adjustable concentration of H(2)SO(4). The calibration system initiates the production of sulfuric acid through the oxidation of SO(2) by OH. The hydroxyl radical is produced by UV photolysis of water vapor. A numerical model calculates the H(2)SO(4) concentration provided at the outlet of the calibration source. From comparison of this concentration and the signals measured by CIMS, a calibration factor is derived. This factor is evaluated to be 1.1 × 10(10) cm(-3), which is in good agreement with values found in the literature for other CIMS instruments measuring H(2)SO(4). The calibration system is described in detail and the results are discussed. Because the setup is external to the CIMS instrument, it offers the possibility for future CIMS intercomparison measurements by providing defined and stable concentrations of sulfuric acid.

A novel fibre-optic UV illumination system for sulphuric acid (H 2 SO 4 ) production has been developed. The illumination system described in this paper provides sufficient ultraviolet light (UV) power while causing practically no thermal effect on the aerosol chamber (temperature variation 2 SO 4 were generated by adjusting the UV light intensity. This paper gives an overview on the design of this new system as well as insights on its performance and application.

Cloud microphysical processes involving the ice phase in tropospheric clouds are among the major uncertainties in cloud formation, weather and General Circulation Models (GCMs). The simultaneous detection of aerosol particles, liquid droplets, and ice crystals, especially in the small cloud-particle size range below 50 μm, remains challenging in mixed phase, often unstable ice-water phase environments. The Cloud Aerosol Spectrometer with Polarisation (CASPOL) is an airborne instrument that has the ability to detect such small cloud particles and measure their effects on the backscatter polarisation state. Here we operate the versatile Cosmics-Leaving-OUtdoor-Droplets (CLOUD) chamber facility at the European Organisation for Nuclear Research (CERN) to produce controlled mixed phase and other clouds by adiabatic expansions in an ultraclean environment, and use the CASPOL to discriminate between different aerosols, water and ice particles. In this paper, optical property measurements of mixed phase clouds and viscous Secondary Organic Aerosol (SOA) are presented. We report observations of significant liquid – viscous SOA particle polarisation transitions under dry conditions using CASPOL. Cluster analysis techniques were subsequently used to classify different types of particles according to their polarisation ratios during phase transition. A classification map is presented for water droplets, organic aerosol (e.g., SOA and oxalic acid), crystalline substances such as ammonium sulphate, and volcanic ash. Finally, we discuss the benefits and limitations of this classification approach for atmospherically relevant concentration and mixtures with respect to the CLOUD 8–9 campaigns and its potential contribution to Tropical Troposphere Layer (TTL) analysis.

In this study, we investigate the composition of nucleated nanoparticles formed from sulphuric acid, ammonia, amines, and oxidised organics in the CLOUD chamber experiments at CERN. The investigation is carried out via analysis of the particle hygroscopicity (size range of 15-63 nm), ethanol affinity (15-50nm), oxidation state (

Recent studies suggest that dimethylamine could be a key ternary species in the formation and early growth of atmospheric aerosol particles. We report on nucleation studies for the ternary system of sulfuric acid, water and dimethylamine which have been performed at the CERN CLOUD chamber. These studies were conducted at atmospherically relevant concentrations of sulfuric acid and dimethylamine at 278 K and 38% RH. Two newly developed Chemical Ionization-Atmospheric Pressure interface-Time of Flight-Mass Spectrometers (CIAPi-TOF-MS) were used to measure the time-resolved concentration of neutral clusters containing sulfuric acid and dimethylamine. Results from other instrumental techniques are included in the analysis as well to obtain a deeper insight into the occurring mechanisms. It is the first time that the neutral nucleation pathway has been studied in such detail from the early generation of sulfuric acid monomers up to particle sizes reaching several nanometers.

A comparison between the binary Sulphuric Acid Water NUCleation model SAWNUC and CLOUD results is presented. Comparison includes direct comparison with a battery of particle counters of various counting efficiencies and APi-TOF charged cluster distribution. A good agreement is found for nucleation rates at various temperatures.

The mechanisms behind the nucleation of vapors forming new particles in the atmosphere had been proven difficult to establish. One main aim of the CLOUD experiment was to explore in detail these first steps of atmospheric new particle formation by performing extremely well controlled laboratory experiments. We examined nucleation and growth in the presence of different mixtures of vapors, including sulfuric acid, ammonia, dimethylamine, and oxidation products of pinanediol or α-pinene. Among the employed state-of-the-art instrumentation, a high-resolution mass spectrometer that directly sampled negatively charged ions and clusters proved particularly useful. We were able to resolve most of the chemical compositions found for charged sub-2nm clusters and to observe their growth in time. These compositions reflected the mixture of condensable vapors in the chamber and the role of each individual vapor in forming sub-2nm clusters could be explored. By inter-comparing between individual experiments and ambient observations, we try to establish which vapors participate in nucleation in the actual atmosphere, and how.

The formation of new particles for the ternary system involving sulfuric acid, water vapor and ammonia has been studied in detail. The nucleation rates were obtained from experiments at the CERN CLOUD chamber which allows the measurement of new particle formation under very well defined conditions. Some of its key features are the suppression of contaminants at the technological limit and a very precise control of a wide range of temperatures, trace gas concentrations and nucleation rates. The effect of ionizing radiation on the ternary nucleation rates was investigated by using the CERN proton synchrotron beam (beam conditions), natural galactic cosmic rays (gcr conditions) as well as the high voltage clearing field inside the chamber to suppress the effect of charges (neutral conditions). The dependence of the nucleation rate on ion concentration, sulfuric acid and ammonia concentration as well as temperature was studied extensively. This way, an unprecedented set of data was collected giving insight into the role of neutral and charged ternary NH_3 nucleation and the relative importance of the different parameters.

Atmospheric aerosols exert an important influence on climate through their effects on stratiform cloud albedo and lifetime and the invigoration of convective storms. Model calculations suggest that almost half of the global cloud condensation nuclei in the atmospheric boundary layer may originate from the nucleation of aerosols from trace condensable vapours, although the sensitivity of the number of cloud condensation nuclei to changes of nucleation rate may be small. Despite extensive research, fundamental questions remain about the nucleation rate of sulphuric acid particles and the mechanisms responsible, including the roles of galactic cosmic rays and other chemical species such as ammonia. Here we present the first results from the CLOUD experiment at CERN. We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100–1,000-fold. Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. We find that ion-induced binary nucleation of H_(2)SO_(4)–H_(2)O can occur in the mid-troposphere but is negligible in the boundary layer. However, even with the large enhancements in rate due to ammonia and ions, atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary-layer nucleation.