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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union

Special issue guidelines

Atmospheric Chemistry and Physics (ACP) and its discussion forum Atmospheric Chemistry and Physics Discussions (ACPD) offer an efficient new way of publishing special issues for measurement campaigns, conferences, etc. The individual papers are peer-reviewed and published as soon as they are available in regular issues;  they are then labelled as part of the special issue and linked electronically.

The specific advantages are the following:

  • Publication date is not delayed by the latest paper, which is behind in the peer-review process: every individual contribution to the special issue is published as soon as it is available.
  • Efficient interactive discussion of the common theme takes places on the ACPD website.
  • Prepublication of discussion papers in ACPD allows efficient cross-referencing between the final revised papers in ACP.
  • All contributions are efficiently linked and coherently presented on dedicated special issue web pages (an appropriate logo is welcome as a *.jpg file) easily accessible from the ACP/ACPD online libraries.
  • Guest editors can define the order of the published papers on the SI web page.
  • Either a non-peer-reviewed editorial preface or a peer-reviewed scientific paper can be used to introduce a special issue.
  • Print versions are available upon completed publication of all contributions. A minimum order of 20 copies is necessary, and the price will depend on the total number of pages in the special issue.  


    The price per printed copy is calculated as follows:

    number of pages × €0.15
    + softcover and binding (€2.35) (hardcover price on request)
    + priority mail (individually calculated)

    = net price + VAT

    Please contact the Copernicus Publications Production Office for an official offer.

Inter-journal special issues  

A special issue can comprise any number of journals, and the special issue editors can be the same or different and from different journals. The manuscript processing follows the standard special issue procedure of the journal in which the manuscript is submitted. Afterwards, all published papers are co-listed on a joint special issue web page (in addition to the regular chronological volume of each journal).

Special issue proposal & guidelines for editors

To make arrangements for a special issue, please contact one of the ACP executive editors. The following points should be considered:

  • The special issue and all manuscripts to be published in it must be within the journal scope and comply with the manuscript types and with the same quality standards as regular submissions to ACP. Please notice and consider in particular that the journal scope is focused on studies with general implications for atmospheric science rather than investigations which are primarily of local or technical interest.
  • ACP special issues usually have a few dedicated special issue editors, amongst whom at least one should be a member of the ACP editorial board with experience in the subject area of the special issue. Please contact appropriate board members directly to see if they are ready to act as co-editor for the planned special issue. The number of special issue editors should reflect the expected number of submissions (about one editor per six submissions per year). Normally, the special issue editors should not be closely involved in the work from which the special issue arises. If appropriate – especially for large special issues – one or two closely involved scientists may become special issue editors but should help with the editor assignment process rather than handling submissions by themselves.
Please provide the following information:

  • title of the special issue;
  • names, affiliations, and short CVs of the proposed special issue editors;
  • start date & end date of submission;
  • a statement of the purpose of the special issue (including information on whether the special issue will include only invited papers or whether it is open for all submissions within the scope of the special issue).

Responsibilities of special issue editors:

  • to coordinate a rigorous peer-review process (at least two independent referees);
  • to ensure that the English is at a high level and request copy-editing if necessary.

To browse existing special issues follow the links ACPD special issues and ACP special issues, respectively.

Scheduled special issues

The following special issues are scheduled for publication in ACP and its discussion forum ACPD:

Pan-Eurasian Experiment (PEEX) 
  • Guest editors: V.-M. Kerminen, M. Heimann, D. Spracklen, T. Laurila, A. Ding, and I. Salma
  • Timeline: 01 Jun 2015 – 31 Dec 2018

The Pan-Eurasian Experiment (PEEX) is a multi-disciplinary, multi-scale and multi-component research infrastructure and capacity building programme. The PEEX originated from a bottom-up approach by the science community and is aimed at resolving the major uncertainties in Earth system science and global sustainability issues concerning the Arctic and boreal Pan-Eurasian regions as well as China. The PEEX solves interlinked global, grand challenges influencing human well-being and societies in northern Eurasia and China, by establishing and maintaining long-term, coherent and coordinated research activities as well as continuous, comprehensive research and educational infrastructures. The scientific issues covered by PEEX include climate change, air quality, biodiversity loss, chemicalisation, food supply, fresh water and the use of natural resources through mining, industry, energy production and transport. Our approach is integrative and interdisciplinary, recognizing the important role of the Arctic and boreal ecosystems in the Earth system.

Amazon Tall Tower Observatory (ATTO) Special Issue 
  • Guest editors: M. Kulmala, L. Ganzeveld, and G. Fisch
  • Timeline: 20 Mar 2015 – 30 Apr 2019

The Amazon Tall Tower Observatory (ATTO) is a flagship long-term measurement station at a pristine location in the center of the Amazon rainforest, 160 km northeast of Manaus. It consists of a 325-meter tower and several 80-meter towers with instrumentation for meteorological, micrometeorological, trace gas, and aerosol measurements. At the ATTO site, studies on a wide range of topics – including trace gas chemistry, greenhouse gas measurements, aerosol chemistry and microphysics, biosphere–atmosphere exchange fluxes, micrometeorology, and ecology – have been conducted since its inception in early 2012. The special issue is open to articles discussing results from these studies; papers on research at related sites in central Amazonia are also welcome.

Ten years of Ozone Monitoring Instrument (OMI) observations (ACP/AMT Inter-Journal SI) 
  • Guest editors: V. Aquila, F. Boersma, B. N. Duncan, N. Kramarova, G. de Leeuw, A. Richter, V. Sofieva, P. Stammes, J. Tamminen, and T. Wagner
  • Timeline: 17 Mar 2015 – 28 Feb 2016

The Ozone Monitoring Instrument (OMI) was launched on-board the Earth Observing System (EOS) Aura satellite on 15 July 2004 in a polar orbit with an afternoon equator crossing time near 13:30. OMI is a wide-swath, nadir-looking, push-broom imaging spectrometer, measuring Earth radiance and solar irradiance from ultraviolet to visible wavelengths (270–500 nm) with a spectral resolution of about 0.5 nm. The vertical columns of several trace gases are retrieved with better spatial and temporal sampling than previous instruments of its type. In particular, OMI observations of nitrogen dioxide, sulfur dioxide, and formaldehyde have enabled new applications in air quality (e.g. emission estimates) and hazard monitoring (e.g. volcanic cloud detection for aviation safety). Observations of the ozone abundance and estimates of UV radiation at the ground are used to track the effects of the Montreal Protocol. OMI observations of tropospheric ozone and aerosols together with minor trace gases provide global input for climate research.

OMI is one of the four instruments on the Aura platform. Together with the three other instruments – the High Resolution Dynamics Limb Sounder (HIRDLS), the Microwave Limb Sounder (MLS), and the Tropospheric Emission Spectrometer (TES) – Aura has functioned as an integrated platform for atmospheric composition measurements. Aura is part of a constellation of satellites (including the Aqua platform) in similar afternoon orbits known as the A-train. Having many different types of instrumentation in this constellation allows for synergetic uses of the data sets.

In this OMI special issue, we highlight scientific research accomplished with 10 years of OMI atmospheric composition measurements, discuss recent improvements in OMI retrieval algorithms and methodologies to utilize the data, and present the status of various OMI data products.

The Dutch–Finnish OMI instrument is currently operational on the NASA Earth Observing System (EOS) Aura satellite and was developed under the assignment of the Netherlands Space Office (NSO) and Tekes – Finnish Funding Agency for Innovation.

Global and regional assessment of intercontinental transport of air pollution: results from HTAP, AQMEII and MICS 
  • Guest editors: F. Dentener, S. Galmarini, C. Hogrefe, G. Carmichael, and K. Law
  • Timeline: 01 Mar 2015 – 01 Dec 2016

The special issue is open to all publications that inform about the aspects of intercontinental transport of air pollution and provide answers to the HTAP scientific questions:

  1. What fraction of air pollution concentrations or deposition can be attributed to sources of contemporary anthropogenic emissions within the region as compared to extra-regional, non-anthropogenic or legacy sources of pollution?
  2. How do these fractions impact on human health, ecosystems and climate change?
  3. How sensitive are regional pollution levels and related impacts to changes in the sources of the various fractions?
  4. How will the various fractions and sensitivities defined above change as a result of expected air pollution abatement efforts or climate change?
  5. How do the availability, costs and impacts of additional emission abatement options compare across different regions?

We especially welcome publications evaluating the joint HTAP, AQMEII and MICS modelling experiments as well as publications developing new methodologies to assess intercontinental transport or air pollution, describing and evaluating observational and emission data sets used in experiments and their relevance for hemispheric transport of air pollution.

The Saharan Aerosol Long-range Transport and Aerosol-Cloud-interaction Experiment (SALTRACE) (ACP/AMT Inter-Journal SI) 
  • Guest editors: B. Weinzierl, U. Wandinger, C. Flamant, C. Hoose, C. Ryder, and J. Schwarz
  • Timeline: 16 Feb 2015 – 28 Feb 2017

Wind-borne mineral dust can affect climate through its interaction with radiation and its role in cloud microphysical processes. In spite of this importance, there has been little research on the long-range transport of mineral dust. In particular critical understanding of the transformations of mineral dust during long-range transport including changes in physical and chemical properties of the particles and the roles of various removal processes during transport is lacking. In addition, climate change threatens to change dust emission rates and hence future dust impacts.

To investigate the long-range transport of mineral dust from the Sahara into the Caribbean, and to study the impact of aged mineral dust on both the radiation budget and cloud microphysical processes, the Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE) was conducted in June/July 2013. During SALTRACE, mineral dust from several dust outbreaks was studied under a variety of atmospheric conditions, and a comprehensive data set on chemical, microphysical and optical properties of aged mineral dust was gathered.

SALTRACE was a German initiative involving scientists from Europe, Cabo Verde , the Caribbean and the US. It was designed as a closure experiment combining ground-based, airborne, satellite and modelling efforts. Ground-based lidar, in situ aerosol and sun photometer instruments were deployed on Barbados (main SALTRACE super-site), Cabo Verde and Puerto Rico. The DLR research aircraft Falcon carried an extensive suite of in situ and remote-sensing instruments and spent more than 110 flight hours studying the long-range transport of mineral dust between Senegal, Cabo Verde, the Caribbean and Florida.

SALTRACE was highly successful and allowed the collection of a unique mineral dust data set which will be presented in this SI, including papers on the experimental, theoretical, and modelling results, as well as instrument and algorithm developments related to the SALTRACE field experiment.

Anthropogenic dust and its climate impact 
  • Guest editors: W. Birmili, D. Covert, K. Kai, and T. Takamura
  • Timeline: 01 Feb 2015 – 31 Jan 2017
  • Articles ACPD

The Modular Earth Submodel System (MESSy) (ACP/GMD Inter-Journal SI) 
  • Coordinator: P. Jöckel
  • Papers are handled by ACP co-editors
  • Timeline: 08 Oct 2014 – indefinite

The Modular Earth Submodel System (MESSy) is a multi-institutional project providing a strategy and the software for developing Earth System Models (ESMs) with highly flexible complexity.

The strategy follows a bottom-up approach, meaning that the various processes and diagnostic tools are implemented as so-called submodels, which are technically independent of each other and strictly separated from the underlying technical model infrastructure, such as memory management, input/output, flow-control, etc.

The MESSy software provides generalized interfaces for the standardized control and interconnection (coupling) of these submodels.

The present time-unlimited Special Issue hosts scientific and technical documentation and evaluation manuscripts concerned with the Modular Earth Submodel System and the models build upon it. Moreover, it comprises manuscripts about scientific applications involving these models.

The Geoengineering Model Intercomparison Project (GeoMIP): Simulations of solar radiation reduction methods (ACP/GMD Inter-Journal SI) 
  • Guest editors: U. Lohmann, N. Vaughan, L. M. Russell, and B. Kravitz
  • Timeline: 02 Oct 2014 – 30 Sep 2016

The Geoengineering Model Intercomparison Project (GeoMIP) has been highly successful in identifying robust climate model response to various geoengineering scenarios. There are currently seven core GeoMIP simulations, with another four submitted as GeoMIP's contribution to CMIP6. These experiments evaluate model response to various forms of geoengineering, focusing on solar dimming, stratospheric sulfate aerosol injections, marine cloud brightening via sea spray, and cirrus cloud thinning. In this special issue, we examine results from these simulations that have been conducted by 15 climate modeling centers from around the world. The results presented here provide a key source of information about the range of potential climate effects from geoengineering, any possible unintended side effects that geoengineering may cause, and the efficacy of geoengineering as a response to climate change. These simulations also reveal fundamental climate responses to radiative forcing, illuminating various feedback processes and interactions between different components of climate models.

Aerosol-Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) (ACP/BG Inter-Journal SI) 
  • Guest editors: W. T. Sturges, L. M. Russell, C. Robinson, L. Bopp, H. Wernli, and M. Krämer
  • Timeline: 26 Sep 2014 – 30 Sep 2017

Coupled chemistry–meteorology modelling: status and relevance for numerical weather prediction, air quality and climate communities (SI of EuMetChem COST ES1004) (ACP/GMD Inter-Journal SI) 
  • Guest editors: A. Baklanov, B. Vogel, and S. Freitas
  • Timeline: 28 Aug 2014 – 31 Aug 2015

Data assimilation in carbon/biogeochemical cycles: consistent assimilation of multiple data streams (BG/ACP/GMD Inter-Journal SI) 
  • Guest editors: M. Scholze, M. Heimann, V. Brovkin, C. Sierra, and C. Gerbig
  • Timeline: 01 Jan 2015 – 31 Dec 2015

Biogeochemical processes, tropospheric chemistry and interactions across the ocean–atmosphere interface in the coastal upwelling off Peru (BG/OS/ACP/AMT Inter-Journal SI) 
  • Guest editors: H. Bange, A. Chaigneau, A. Engel, C. Garbe, A. Kock, W. Naqvi, B. Thamdrup, B. Ward, C. Robinson, and A. Richter
  • Timeline: 01 Aug 2014 – 31 Oct 2015

The R/V Meteor cruise M91 (Callao-Callao) took place off Peru from 01 December to 26 December 2012. The overall goal of M91 was to conduct an integrated biogeochemical study on the upwelling region off Peru and its adjacent oxygen minimum zone in order to assess its importance for the emissions of various climate-relevant atmospheric trace gases and tropospheric chemistry. The various work packages of M91 included measurements of (1) atmospheric and dissolved trace gases, (2) aerosols, (3) nitrogen processes and isotopes in the water column, (4) dissolved organic matter in the surface microlayer, (5) upwelling velocity, and (6) exchange fluxes across the ocean−atmosphere interface. M91 was funded by the German BMBF project SOPRAN (Surface Ocean Processes in the Anthropocene; http://www.sopran.pangaea.de), which is a contribution to the International SOLAS (Surface Ocean – Lower Atmosphere Study; http://www.solas-int.org).

Marine trace gases and aerosols over tropical oceans (AMT/ACP Inter-Journal SI) 
  • Guest editors: L. Carpenter, M. Uematsu, and R. Volkamer
  • Timeline: 02 Jun 2014 – 31 Jul 2015

Data collection, analysis and application of speciated atmospheric mercury 

Meso-scale aerosol processes, comparison and validation studies from DRAGON networks (ACP/AMT Inter-Journal SI) 
  • Guest editors: P. Quinn, P. Formenti, and M. Schulz
  • Timeline: 01 Apr 2014 – 01 Oct 2015

Provide a summary of Meso-scale aerosol field campaign research from dense distributions of remote sensing (RS) networks such as AERONET and related in situ and RS aerosol observations from surface, airborne and satellite platforms.

Recent aerosol field campaigns with AERONET have emphasized local to regional aerosol characterization for a variety of aerosol types, concentrations and meteorological regimes. The resulting networks called Distributed Regional Aerosol Gridded Observation Networks (DRAGON) are meso-scale short-term dense networks of sun and sky scanning photometers and ancillary observations established to characterize aerosol dynamics at a resolution commensurate with meso-scale aerosol processes. The DRAGON campaigns have been carried out successfully in the U.S. (Washington, D.C./Maryland, Texas and California), as well as in Asia including China, Korea, Japan, Malaysia and Singapore and in Germany for the past several years. This special issue will emphasize results from these DRAGON campaigns and similar network data for aerosol process studies, aerosol-cloud interactions, regional radiative forcing, in-network retrieval comparisons and validations, in situ vs. remote sensing comparisons as well as satellite and airborne validations and comparisons.

Uintah Basin Winter Ozone Studies (ACP/AMT Inter-Journal SI) 
  • Guest editors: J. Seinfeld, P. Shepson, J. Collett, and E. Apel
  • Timeline: 27 Mar 2014 – 31 May 2015

Elevated ground-level ozone has been observed in the wintertime in two air basins in the western US. These basins have extensive oil and gas production operations that involve a unique combination of NOx and VOC sources, in conjunction with persistent cold pool conditions creating a shallow boundary layer over snow-covered ground. The Uintah Basin Winter Ozone Studies (UBWOS) took place during the winters of 2012, 2013, and 2014 in the Northeast corner of the state of Utah. The goal of these intensives was to obtain a detailed understanding of the chemistry causing high ozone in this air basin to inform the development of effective control strategies could be implemented. This special issue will collect papers describing some of the measurement techniques employed and analysis of the extensive data sets of VOC, odd-nitrogen, radical source species, fine-scale meteorology, and spatial distributions of O3.

Oxidant Production over Antarctic Land and its Export (OPALE) 
  • Guest editors: T. Bartels-Rausch, J. W. Bottenheim, C. Barbante, and S. Preunkert
  • Timeline: 11 Mar 2014 – 01 Jan 2016

The OPALE (Oxidant Production over Antarctica Land and its Export) project aims to quantify, understand, and model the level of oxidants present in the lower atmosphere of Antarctica. The oxidants are very abundant there in relation with the presence of large snow and ice-covered areas. Previous studies focused on oxidants present in the lower atmosphere at the South Pole and at several coastal sites located in West Antarctica. Based on atmospheric measurements carried out at the Concordia (DC) station located at 3250 m elevation on the high Antarctic plateau and at the coastal site of Dumont d’Urville (DDU), the project focuses on oxidants present over the East part of the Antarctic continent. The obtained data would be of great interest for the scientific communities working on numerous aspects of the global change (coupling atmosphere-ice-climate, interpretation of deep ice cores mainly drilled in East Antarctica, atmospheric chemistry over snow-covered regions).

Atmospheric measurements carried out at DDU and DC included HOx radicals, chemical species controlling the radical productions (O3, HONO, H2O2, HCHO, NO, and NO2), and an isotopic approach to highlight oxidation mechanisms. The field data obtained during the two field campaigns are used to:

  • Examine the levels of oxidants over the high Antarctic plateau and factors controlling their budgets;
  • Evaluate the impact of this very oxidizing boundary layer at coastal regions of East Antarctica on the basis of in situ observations and transport-chemistry model simulations.

HD(CP)2 Observational Prototype Experiment 
  • Guest editors: S. Buehler and H. Russchenberg
  • Timeline: 01 Mar 2014 – 31 Dec 2015

The "HD(CP)2 Observational Prototype Experiment" HOPE has been designed to provide a unique view into clouds and their radiative aspects by combining state-of-the art remote sensing instrumentation. Such dense observations on process scale are necessary to capture the sub-grid variability of todays numerical weather prediction model and to assess microphysical properties that are subject to parameterizations even at high-resolution simulations. Specifically, HOPE observations will be used for a critical model evaluation HD(CP)2 that will be run at 100 m resolution over central Europe. The main goals of HOPE are to provide a most complete set of calibrated products of atmospheric parameters and to identify processes relevant for the formation of clouds and precipitation.

In order to achieve the dense instrumental coverage the agricultural area around the atmospheric observatory JOYCE (Jülich Observatory for Cloud Evolution) in Western Germany was chosen and complemented with two additional supersites and networks from April to May 2013. Three supersites formed a triangle with about 4 km side length. The deployed instruments include Doppler lidars, Raman lidars (aerosol & cloud particles, water vapor, temperature), water vapor DIAL, ceilometers, microwave radiometers, cloud Doppler radars, sun photometer, different types of meteorological towers (up to 120 m), a network pyranometer, sky imagers, as well as precipitation radar partly with polarization capabilities. This set of instruments forms the densest setup of remote sensing and surface flux instruments to date.

Together with in total radiosonde launches (every 3 hours during intensive observation periods) the instruments captured the mean and turbulent thermodynamic state of the atmosphere and the vertically resolved and to some extend the 3d-resolved distribution of aerosol, cloud- and precipitation-particles as function of time over a horizontal domain of 10 by 7 km2. Horizontal fields of standard meteorological parameter and surface fluxes of latent and sensible heat as well as solar and thermal radiation fluxes have been obtained. For the first time to our knowledge, a combination of scanning water vapor, temperature and Doppler lidar as well as coordinated scans with microwave radiometer and cloud radar were performed. Categories of meteorological events were identified and data examples of these categories will be presented and discussed. It is demonstrated how the combination of active and passive, optical and microwave ground-based remote sensing yields also via desired redundancy a consistent picture of the atmospheric state and that through temporal changes of atmospheric and surface flux properties insights on lower atmospheric processes are revealed. The contributing manuscripts will briefly describe the set of instruments and the corresponding retrieved physical parameter with their spatial and temporal resolution followed by a synopsis of the meteorological conditions during the campaign. On the basis of characteristic intensive observation periods, case studies for clear skies, convective clouds, and precipitation will be presented and discussed. In a follow-up campaign in September 2013 in Melpitz, Germany, additional aerosol and cloud microphysics measurements on-board a helicopter-based platform were performed and will be reported as well.

South AMerican Biomass Burning Analysis (SAMBBA) 
  • Guest editors: H. Coe, K. Longo, M. Andreae, S. Martin, and G. Myhre
  • Timeline: 01 Jan 2014 – 31 Jul 2018

Biomass burning aerosol (BBA) exerts a considerable impact on regional radiation budgets as it significantly perturbs the surface fluxes and atmospheric heating rates and its cloud nucleating (CCN) properties perturb cloud microphysics and hence affect cloud radiative properties, precipitation and cloud lifetime. It is likely that such large influences on heating rates and CCN will affect regional weather predictions in addition to climatic changes. Amazonia is one of the most important biomass burning regions in the world, being significantly impacted by intense biomass burning during the dry season leading to highly turbid conditions, and is therefore a key environment for quantifying these processes and determining the influence of these interactions on the weather and climate of the region.

The South AMerican Biomass Burning Analyses (SAMBBA) programme is a major international consortium programme. The programme has delivered a suite of ground, aircraft and satellite measurements of Amazonian Biomass Burning Aerosol during a field study that took place in September 2012. SAMBBA has used this data in a suite of analyses that aims to:

  1. improve our knowledge of BB emissions;
  2. challenge and improve the latest aerosol process models;
  3. challenge and improve satellite retrievals;
  4. test predictions of aerosol influences on regional climate and weather over Amazonia and the surrounding regions made using the next generation of climate and NWP models with extensive prognostic aerosol schemes; and
  5. assess the impact of .biomass burning on the Amazonian biosphere.

The main field experiment was based in Porto Velho, Brazil and investigated the dry season and onset of the wet season. The UK large research aircraft (FAAM) sampled aerosol chemical, physical and optical properties and gas phase precursor concentrations. Measurements of radiation were also made using advanced radiometers on board the aircraft and satellite data are also being used. The influences of biomass burning aerosols are highly significant at local, weather, seasonal, and climate temporal scales necessitating the use of a hierarchy of models to establish and test key processes and quantify impacts. The study is challenging models carrying detailed process descriptions of biomass burning aerosols with the new, comprehensive observations being made during SAMBBA to evaluate model performance and to improve parameterisations. Numerical Weather Prediction and Climate model simulations with a range of complexity and spatial resolution are being used to investigate the ways in which absorbing aerosol may influence dynamics and climate on regional and wider scales. At the heart of the approach is the use of a new range of models that can investigate such interactions using coupled descriptions of aerosols and clouds to fully investigate feedbacks at spatial scales that are sufficiently well resolved to assess such processes.

The community version of the Weather Research and Forecasting Model as it is coupled with Chemistry (WRF-Chem) (GMD/ACP Inter-Journal SI) 
  • Guest editor: G. Grell
  • Timeline: 20 Dec 2013 – 31 Dec 2018

The Weather Research and Forecast community modelling system coupled with Chemistry (WRF-Chem) provides the capability to simulate and forecast weather, trace gases, and aerosols from hemispheric to urban scales. WRF-Chem is a community model. WRF-Chem is an online modelling system which includes the treatment of the aerosol direct and indirect effect. It incorporates many choices for gas phase chemistry and aerosols with degrees of complexity that are suitable for forecasting and research applications. Due to its versatility WRF-Chem is attracting a large user and developer community world-wide. The present time-unlimited Special Issue hosts scientific technical documentation and evaluation manuscripts concerned with the community version of WRF-Chem.

Results from the ice nucleation research unit (INUIT) (ACP/AMT Inter-Journal SI) 
  • Guest editors: J. Abbatt, A. Bertram, D. J. Cziczo, and B Ervens
  • Timeline: 18 Dec 2013 – 31 Dec 2016

INUIT - Ice Nuclei Research Unit:

Ice crystals play an important role for the radiative properties of clouds as well as for the formation of precipitation. Mixed-phase clouds are clouds that consist of both, super-cooled liquid droplets and ice particles. They account for a large fraction of the clouds in the atmosphere but our knowledge on the microphysical properties of these clouds is still limited. An important question is how ice forms in these clouds. While it is well established that an ice nucleus is needed as a seed for the initial formation of an ice crystal in mixed-phase clouds many questions remain to be answered on the concentration and variability of atmospheric ice nuclei and their physico-chemical properties.

The Research Unit "INUIT" (Ice Nuclei research UnIT) studies heterogeneous ice formation in the atmosphere. The studies include laboratory investigations on the nature of the nucleation process and on the chemical, microphysical and biological characterization of atmospherically relevant ice nuclei as a function of temperature and water saturation. Intensive field experiments are conducted as well as monitoring surveys to study the number concentration, variability, size, chemical composition, surface properties and sources of atmospheric ice nuclei in different freezing modes. Various state-of-the-art methods and facilities are used for the characterization of the ice nuclei. Ice nucleating properties of mineral dust particles, volcanic ash, and biological ice nuclei are a focus of attention of the INUIT research unit. The results of the experimental investigations are fed into a cloud process model and a cloud-resolving meso-scale model to improve the representation of clouds in the models, to simulate cloud processes and to quantify the contribution of ice nuclei types and freezing modes.

The INUIT research unit comprises 9 research projects from 8 partner institutes (Goethe-University of Frankfurt/Main, University of Bielefeld, University of Mainz, Technical University Darmstadt, Leibniz-Institute for Tropospheric Research, Max-Planck Institute for Chemistry and Karlsruhe Institute for Technology). It is funded by the Deutsche Forschungsgemeinschaft DFG (grant no. FOR 1525).

The Boundary-Layer Late Afternoon and Sunset Turbulence (BLLAST) project (ACP/AMT Inter-Journal SI) 
  • Guest editors: R. J. Beare, Y. Brunet, E. Pardyjak, and S. Galmarini
  • Timeline: 07 Nov 2013 – 31 Dec 2015

The planetary boundary layer plays a vital role in the earth system through its controls on the transfer of heat, momentum, humidity, and trace gases between the surface and the atmosphere. The transition that occurs in late afternoon, from the mixed convective boundary layer to a residual layer overlying a stably stratified surface layer in late afternoon raises several scientific issues that are still poorly understood. For example, there is still a need to relate the characteristics of the turbulence energy decay and its vertical structure with the boundary-layer processes and forcings. Also, the evolution of the characteristic length scales of turbulence remains unclear, and needs more observations and understanding.

The BLLAST project has gathered a group of research scientists from several countries in Europe and the US to work together with the purpose of increasing our knowledge of the late afternoon turbulence processes in order to improve the representation of the diurnal cycle in the numerical weather prediction and global models. The BLLAST project emerged in 2009, and lead to a field campaign that was conducted from 14 June to 8 July 2011 in southern France. The field campaign consisted of a range of integrated instrument platforms including: full-size aircraft, Remotely Piloted Airplane Systems (RPAS), remote sensing instruments, radiosoundings, tethered balloons, surface flux stations, and various meteorological towers deployed over different heterogeneous surfaces. These instruments measured the differences in the vertical structure and evolution of the late afternoon transition among a mosaic of vegetated surfaces. This special issue is an expose of current BLLAST studies that include: the analysis of field data, Large Eddy Simulations (LES) and mesoscale simulations. These issue aims to improve our understanding of processes, develop new parameterizations, and evaluate forecast models during this transitional period.

Study of Ozone, Aerosols and Radiation over the Tibetan Plateau (SOAR-TP) 
  • Guest editors: R. Sander, H. Su, T. Wagner, T. Wang, Y. Cheng, and X. Xu
  • Timeline: 31 Oct 2013 – 31 Dec 2017

The Tibetan Plateau, also known in China as the Qinghai-Tibet Plateau, has a large influence on atmospheric circulation, hydrological cycle and climate in East Asia as well as the Northern Hemisphere. The plateau, sometimes called "the Roof of the World" or "the Third Pole", covers a huge area located in 73-105 E longitude and 26-40 N latitude, with mean surface elevation of 4000-5000 m above sea level. It has long been considered as one of the remote regions in the Eurasian continent that are relatively less influenced by pollution from human activities. While natural processes that control the temporal and spatial variations of atmospheric composition over the Tibetan Plateau are still inadequately understood, the influence of long-range transport of pollutants from surrounding areas, e.g. South and Southeast Asia, and farther regions on the background atmosphere of the Tibetan Plateau and associated climate impacts have become a scientific issue to be intensively addressed.

Long-term measurements of trace gases, aerosols and radiation have been performed at several remote sites in the Tibetan Plateau region, including e.g. the Waliguan Global Baseline Station and the Shangri-la Regional Background Station (both operated by China Meteorological Administration) and the Nam-Co Comprehensive Observation and Research Station (operated by Institute of Tibetan Plateau Research, Chinese Academy of Sciences). Intensive field campaigns were carried out based on these stations and some other sites of the region during different periods to investigate the levels and variation controlling factors of atmospheric ozone and aerosols over the plateau. Observations include in-situ measurements of ozone and related trace species, in-situ and sampling measurements of aerosol physical properties and chemical composition, sounding of ozone and water vapor, lidar measurements of aerosols, and ground-based remote sensing of selected trace gases, etc. Models are also used to compare with measurement results and interpret data. The purpose of this issue is to expand our understanding of physic-chemical and transport processes that largely influence atmospheric ozone and aerosols as well as radiation over the Tibetan Plateau.

CHemistr​y and AeRosols Medit​erranean EXperiments​ (ChArMEx) (ACP/AMT ​Inter-Journal SI) 
  • Guest editors: N. Mihalopoulos, W. Lahoz, X. Querol, C. Reeves, F. Dulac, O. Dubovik, and J.-L. Attie
  • Timeline: 14 Oct 2013 – 31 Dec 2015

VERDI – Vertical Distribution of Ice in Arctic Clouds (ACP/AMT Inter-Journal SI) 
  • Guest editors: C. Hoose, M. Shupe, and P. Eriksson
  • Timeline: 01 Dec 2013 – 31 Dec 2015

The scientific expedition VERDI (short for Vertical Distribution of Ice in Arctic Clouds) is a cooperation project of various German research institutes with the goal to measure the microphysical and optical properties of Arctic boundary-­layer clouds, and to investigate the effects that those clouds can have on the energy budget in the Arctic atmosphere. The VERDI participants have successfully performed airborne measurements of the microphysical and radiative properties of clouds in the Canadian Arctic (based in the town of Inuvik in the Northwest Territories) in April and May 2012, and are now working on the data processing and evaluation. At least seven publications on VERDI results (listed below) are planned, and it is desired to bundle these in the planned ACP/AMT inter-­journal special issue. The special issue is open for all submissions within its scope.

Limb observations of the middle atmosphere by space- and airborne instruments (ACP/AMT Inter-Journal SI) 
  • Guest editors: C. von Savigny, G. Stiller, E.Kyrölä, F. Khosrawi, P. Liebing, and S. Buehler
  • Timeline: 29 Aug 2013 – 31 Aug 2015

Spaceborne and airborne remote sensing measurements of the Earth’s atmosphere in limb geometry provide vertical profile information of atmospheric minor constituents and background parameters with generally good vertical resolution. These measurements include solar, lunar and stellar occultation measurements, measurements of thermal emissions in the microwave and infrared spectral regions, observations of limb-scattered solar radiation as well as measurements of non-thermal airglow emissions in the optical spectral range. Over the last decade Limb measurements in the different spectral regions have greatly improved our understanding of many physical and chemical processes in the Earth’s middle atmosphere, comprising the stratosphere and mesosphere.

The 7th atmospheric limb conference, held at Bremen, Germany in June 2013 was dedicated to all scientific aspects related to middle atmospheric limb measurements, including current and future missions, instrument monitoring, algorithm development and implementation, radiative transfer modeling, validation of data products and scientific analyses based on the retrieved data products. This special issue is an outcome of the 7th atmospheric limb conference, and contributions on all aspects mentioned are welcome. Note that attendance of the conference is not a prerequisite for submitting manuscripts to this special issue.

Haze-fog forecasts and near real time (NRT) data application (ACP/GMD Inter-Journal SI) 
  • Guest editors: J. Brandt, S. Gong, and X.-Y. Zhang
  • Timeline: 11 Jul 2013 – 31 May 2015

Surface Ocean Aerosol Production (SOAP) (ACP/OS Inter-Journal SI) 
  • Guest editors: C. Law, M. Harvey, M. Smith, P. Quinn, N. Harris, and M. Hoppema
  • Timeline: 01 Jul 2013 – 31 Jul 2015

Biologically-active regions of the surface ocean support production of a range of compounds that influence aerosol particle production, composition and properties in the overlying marine boundary layer. In February-March 2012 the SOAP (Surface Ocean Aerosol Production) voyage examined biotic influences on aerosol production to the east of New Zealand, by targeting phytoplankton blooms along the Sub-Tropical Front, with the aim of constraining the relationships between DMS and aerosol flux and characteristics, and phytoplankton biomass and community composition, by multi-disciplinary research within three workpackages:

  • WP1. Surface ocean biogeochemical links with aerosol precursors;
  • WP2. Exchange rate and physical drivers of the transfer of DMS & CO2 and
  • WP3. Organic emissions, nucleation and interactions with the aerosol distribution in the overlying marine boundary layer.

The results of this research voyage will be detailed in this Special Issue, which will contain invited papers only.

East Asia emissions assessment (EA2) 
  • Guest editors: T. Bond, G. Carmichael, G. Frost, H. Su, and Y. Cheng
  • Timeline: 01 Jul 2013 – 30 Jun 2016

Understanding emission fluxes from earth’s surface has considerable scientific importance because the variability of atmospheric composition is largely driven by emissions. Due to the rapid regional economic growth, emissions in East Asia have degraded regional air quality and visibility and damaged human health. East Asia emissions also contribute a large share of the global emissions and dominate the Asian continental outflow that travels across the Pacific. Hence they also have significant impacts on global air quality and climate and attract great attention of scientists and policy makers.

To date developing an understanding of emissions has largely relied on bottom-up approaches that aggregate fuel combustion data and emission factors. The large uncertainty in East Asia bottom-up inventories hampers interpretation of observation data, and has been recognized as the bottleneck in limiting the predictive performances of chemical transport models. The community has made considerable efforts to reduce uncertainties in emission inventories, e.g., development of improved emission models, application of inverse models with top-down constraints from in-situ and satellite observations. However, those different approaches are rarely compared and validated with each other. There are still large gaps among different top-down/bottom-up inventories.

Organized by the Global Emissions InitiAtive (GEIA) China Working Group, the East Asia Emissions Assessment (EA2) is designed to bridge these gaps through the integration of different approaches. The assessment includes inter-comparison of current bottom-up inventories in East Asia, development of novel emission inventory models, observation-based constraints on emissions, and evaluation and uncertainty analysis of different emission quantification approaches. The outputs from EA2 studies will not only help reduce uncertainties in East Asia inventories, but also provide improved emission quantification methodologies that can be applied to other world regions.

Biosphere-atmosphere exchange or organic compounds: impact of intra-canopy processes (CANOPÉE 2011-2014) 
  • Guest editors: J. Rinne, M. Kanakidou, and J. Williams
  • Timeline: 18 Jun 2013 – 31 Dec 2015

The objective of CANOPÉE is to understand and quantify the role of intra-canopy processes in the surface-atmosphere exchange of compounds, focusing on biogenic volatile organic compounds (VOCs), and especially isoprene, which is the first biogenic VOC emitted, and ozone. The novelty of our project is based on the combination of new experimental and modeling approaches, and a multi-disciplinary methodology including branch-scale to canopy-scale measurements for the structural, chemical and ecological characteristics of the canopy. A field campaign was carried out in May-June 2012 at the Observatoire de Haute Provence (OHP/O3HP) in the South part of France, in a large oak (Quercus pubescens) forest site. Measurements were set to investigate the geographical and vertical tree distribution (lidar on-board ULA); the isoprene emission rate at the branch-level (dynamic enclosure chambers); the atmospheric chemical composition inside and above the canopy together with concentrations diurnal and vertical variability for key compounds such as ozone, nitrogen oxides and a variety of VOCs (GC-MS and PTR-MS) or aerosols. Data and observations collected will be integrated in a one-dimensional model (CACHE) to improve our knowledge on the intra-canopy processes and their representation in modeling tools, and regional studies will be performed with the chemistry-transport model CHIMERE to assess the impact of such forest sites on regional chemistry and possible future evolution.

Interactions between climate change and the Cryosphere: SVALI, DEFROST, CRAICC (2012–2016) (TC/ACP/BG Inter-Journal SI) 
  • Guest editors: J. Bäck, M. Bilde, M. Boy, T. R. Christensen, J. O. Hagen, M. Hansson, H. Järvinen, M. Kulmala, T. Laurila, A. Stohl, H. Skov, A. Massling, M. Glasius, and S. M. Noe
  • Timeline: 19 Jun 2012 – 31 Dec 2016

SAPUSS: Solving aerosol problems by using synergistic strategies in the west Mediterranean basin 
  • Guest editors: A. S. H. Prevot, R. M. Harrison, S. Decesari, and R. Vecchi
  • Timeline: 01 Jun 2012 – 01 Jun 2015

Compared to other European regions, the metropolitan area of Barcelona sees relatively high particulate matter due to high anthropogenic emissions, a dry and warm Mediterranean climate and low dispersive conditions due to a unique topographical situation. During the autumn of 2010, the SAPUSS experiment took place, involving measurements of aerosols with multiple techniques occurring simultaneously in order to deduce point source characteristics and to understand the atmospheric processes responsible for their modifications. The unique approach is the large variety of instrumentations deployed simultaneously in a number of monitoring sites used including: a main traffic road, two urban background sites, a regional background site and two towers within the city (150 m and 545 m above sea level, 150 m and 80 m above ground, respectively). The purpose of this issue is to contribute to the advancement of our understanding of the sources and the evolution of aerosols in the atmosphere. This integrated study would also be of interest for other similar sites worldwide.

HCCT-2010: a complex ground-based experiment on aerosol-cloud interaction 
  • Guest editors: G. McFiggans, M. C. Facchini, C. George, and H. Herrmann
  • Timeline: 25 Oct 2011 – 31 Dec 2015

Carbonaceous Aerosols and Radiative Effects Study (CARES) 
  • Guest editors: D. J. Cziczo, T. Bond, G. McFiggans, and J. A. Thornton
  • Timeline: 08 Sep 2011 – 31 Dec 2015

The Pan European Gas-Aerosols Climate Interaction Study (PEGASOS) 
  • Guest editors: A. Laaksonen, E. Nemitz, U. Baltensperger, N. Mihalopoulos, and A. Hofzumahaus
  • Timeline: 04 Aug 2011 – 31 Aug 2015

The Pan European Gas AeroSOls-climate interaction Study (PEGASOS) European large scale integrating project brings together most of the leading European research groups, with state of the art observational and modeling facilities to:

  1. Quantify the magnitude of regional to global feedbacks between atmospheric chemistry and a changing climate and to reduce the corresponding uncertainty of the major ones.
  2. Identify mitigation strategies and policies to improve air quality while limiting their impact on climate change.

The project will combine development of anthropogenic and biogenic emission inventories, laboratory studies in some of the premier European smog chamber facilities, field measurements over Europe using a Zeppelin combined with mobile and fixed ground platforms, air quality and climate models, and policy analysis to achieve its objectives.

The CERN CLOUD experiment (ACP/AMT Inter-Journal SI) 
  • Guest editors: V.-M. Kerminen, J. H. Seinfeld, N. M. Donahue, K. Carslaw, and J. Abbatt
  • Timeline: 20 Jun 2011 – 31 Jul 2016

The SI will include papers on the experimental, theoretical and modelling results related to the CERN CLOUD experiment. The scientific focus of the experiment is to make fundamental measurements of aerosol nucleation under highly controlled laboratory conditions, including the effects of natural and synthetic cosmic rays. There were two campaigns of a month long: the first (2010) focused on inorganic aerosols and cosmic ray influences (NH3/H2SO4). The second campaign (June 2011) focuses on organic impacts on nucleation. There are also detailed modelling studies, plus papers on parameterisation development and global model applications.

Integrated Land Ecosystem-Atmosphere Processes Study (iLEAPS) (ACP/BG Inter-Journal SI) 
  • Guest editors: A.-B. Guenther, P. Artaxo, L. Ganzeveld, H. P. Schmid, M. Kulmala, A. Neftel, A. Arneth, J. Pongratz, N. Saigusa, S. Seneviratne, S. M. Noe
  • Timeline: 01 Jun 2011 – 31 Dec 2015

iLEAPS is the land-atmosphere core project of the International Geosphere-Biosphere Programme (IGBP). The scientific goal of iLEAPS is to provide understanding how interacting physical, chemical and biological processes transport and transform energy and matter through the land-atmosphere interface. Atmospheric Chemistry and Physics (ACP) and Biogeosciences (BG) have opened a joint special issue on iLEAPS-related science, and you are welcome to contribute by sending manuscripts on land-atmosphere interactions to this joint issue via either ACP or BG.

Megapoli-Paris 2009/2010 campaign 
  • Guest editors: A. Baklanov, M. Beekmann, J.-L. Jaffrezo, J.-L. Jimenez, C. Reeves, and R. Vautard
  • Timeline: 04 Mar 2011 – 30 Jun 2015

The MEGAPOLI PARIS campaigns in summer 2009 and in winter 2010 aimed at better quantifying sources of primary and secondary aerosol in and around a large agglomeration and to document their evolution in the megacity plume. A focus was put on carbonaceous aerosol, where uncertainties are major. As related issues, also gas phase photochemistry and the evolution of dynamical conditions during the campaign were addressed. Analysis of experimental data and modelling studies are solicited. Papers on timescales beyond the campaign, but dealing with this target region, are also welcome.

Publications Copernicus