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

Scheduled special issues

The following special issues are scheduled for publication in ACP:

The Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP) (ESD/ACP/CP/GMD inter-journal SI)
15 May 2017–30 Apr 2019 | Guest editors: A. Schmidt and S. Bekki | Coordinators: C. Timmreck, M. Khodri, and D. Zanchettin | Information

Volcanic eruptions are one of the major natural factors influencing climate variability at interannual to multidecadal timescales. However, simulating volcanically forced climate variability is a challenging task for climate models and one of the major uncertainties in near-term climate predictions. The Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP) is an endorsed contribution to the sixth phase of the Coupled Model Intercomparison Project. This multi-journal special issue on VolMIP aims at collecting relevant research results obtained within the VolMIP framework, and specifically concerning different aspects of the radiative and dynamical climatic response to volcanic forcing, detailed description of effects of different implementation of volcanic forcing in current climate models, aspects concerning the dynamical and chemical atmospheric response to volcanic aerosols simulated by global aerosol models, and comparison between reconstructed and simulated climate evolution after major eruptions. Articles in the special issue should contain the following statement: "This article is part of the special issue "The Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP) (ESD/GMD/ACP/CP inter-journal SI)". It does not belong to a conference."

Sources, propagation, dissipation and impact of gravity waves (ACP/AMT inter-journal SI)
15 Mar 2017–31 Dec 2017 | Guest editors: M. Rapp, F.-J. Lübken, J. Gumbel, M. Taylor, and G. Zängl | Information

Gravity waves (GWs) are a ubiquitous phenomenon in a stably stratified atmosphere. GWs are excited by flow over orography and by convection or jet streams and fronts, and may propagate both horizontally and vertically over large distances. Thus, they lead to a significant vertical and horizontal transport of energy and momentum which so far is hardly appropriately accounted for in numerical weather prediction and climate models, which mainly rely on simplified parametrization schemes. In order to investigate sources, propagation, dissipation and impact of GWs, a number of large internationally coordinated research campaigns have been conducted over the past few years. These campaigns involve observations with research aircraft, satellites, research balloons, and ground-based instruments, as well as related modelling efforts. Specifically, these are the series of GW-LCYCLE (Gravity Wave Life CYCLE) campaigns conducted in northern Scandinavia in winter 2013 and 2015/16 as well as the NSF-DEEPWAVE (The DEEP PROPAGATING GRAVITY WAVE EXPERIMENT) campaign conducted in June/July 2014 from New Zealand. The German contributions to these activities were funded in the scope of the ROMIC (Role of the Middle atmosphere in Climate) research focus of the German Ministry for Education and Research as well as the MS-GWAVES (Multi Scale dynamics of Gravity WAVES) research unit funded by the German Science Foundation. For this special issue, we invite contributions describing observations and related modelling studies focusing on results achieved during these field campaigns. However, beyond studies specifically addressing results obtained in the framework of GW-LCYCLE and DEEPWAVE, we also invite any related studies dealing with GW processes and their impact on the atmosphere. Within this framework, contributions focusing on both scientific and methodological aspects will be considered.

Quadrennial Ozone Symposium 2016 – Status and trends of atmospheric ozone (ACP/AMT inter-journal SI)
01 Feb 2017–01 Jun 2017 | Guest editors: S. Reis, A. F. Bais, R. S. Eckman, S. Godin-Beekmann, I. Petropavlovskikh, W. Steinbrecht, P. Young, and M. Shao | Information

The study of ozone is important because of the large role it plays in protecting the Earth from harmful levels of ultraviolet solar radiation and because of its role as a greenhouse gas in the Earth's climate system, as well as the harmful effects of tropospheric ozone on human health, ecosystems, and agricultural production. In 2016, the International Ozone Commission (IO3C) organised its Quadrennial Ozone Symposium (QOS 2016) with more than 300 participants presenting the latest findings and emerging research on the full range of ozone-related topics. This special issue invites submissions of papers presented at the QOS 2016 related to the following broad subject areas:

  • stratospheric ozone
  • tropospheric ozone
  • ozone chemistry–climate interactions
  • global ozone observations and measurement techniques.

Please contact the corresponding guest editor ( prior to submitting a manuscript to this special issue.

The ACRIDICON-CHUVA campaign to study deep convective clouds and precipitation over Amazonia using the new German HALO research aircraft (ACP/AMT inter-journal SI)
11 May 2016–31 Dec 2017 | Guest editors: S. A. Penkett, S. A. Buehler, U. Schumann, and A. Heymsfield | Information

Between 1 September and 4 October 2014 a combined airborne and ground-based measurement campaign was conducted to study tropical deep convective clouds over the Brazilian rainforest. The German HALO (High Altitude and LOng range) research aircraft and extensive ground-based instrumentation were deployed in and near Manaus (state of Amazonas). The campaign was part of the German-Brazilian ACRIDICON-CHUVA venture to quantify aerosol-cloud-precipitation interactions and their thermodynamic, dynamic, and radiative effects by in situ and remote sensing measurements over Amazonia. ACRIDICON is the abbreviation for "Aerosol, Cloud, precipitation, and Radiation Interactions and DynamIcs of CONvective cloud systems", and CHUVA stands for "Cloud processes of tHe main precipitation systems in Brazil: a contribUtion to cloud resolVing modeling and to the GPM (globAl precipitation measurement)". The ACRIDICON-CHUVA field observations were carried out in cooperation with the second intensive operating period of GoAmazon 2014/15. Five scientific topics were pursued: (a) cloud vertical evolution and life cycle (cloud profiling), (b) cloud processing of aerosol particles and trace gases (inflow and outflow), (c) satellite and radar validation (cloud products), (d) vertical transport and mixing (tracer experiment), and (e) cloud formation over forested/deforested areas. Data were collected in near-pristine atmospheric conditions and in environments polluted by biomass burning and urban emissions.

Atmospheric emissions from oil sands development and their transport, transformation and deposition (ACP/AMT inter-journal SI)
22 Apr 2016–31 Oct 2017 | Guest editors: J. W. Bottenheim, J. G. Murphy, J. Liggio, J. Brook, and S.-M. Li | Information

The oil sands of Alberta, Canada, are of international interest due to the potential environmental impacts, from local to global scales, of their extraction and processing to provide non-conventional fossil fuels to consumers in North America and globally. The governments of Canada and the province of Alberta launched the Joint Oil Sands Monitoring (JOSM) program in 2012 to help address knowledge gaps regarding long-term cumulative effects of oil sands' development and production. JOSM is a regionally focused program; however, the knowledge gained is applicable to extra heavy oil production elsewhere, given the large known global reserves of heavy oil and bitumen.

The purpose of this special issue is to bring together the scientific results of atmospheric-related JOSM studies, which have been largely conducted since 2013, although some of the potential papers could involve data obtained in earlier years. Other submissions within this scope could also be considered. The results would be derived from measurements from the ground as well as aircraft and satellite overpasses. Applications and evaluations of high-resolution modeling will also be part of this research portfolio. While the studies are to be focused on emissions and ambient levels, as well as deposition, with regard to the oil sands region in Alberta, and therefore referring particularly to conditions in that area, results will have a broader relevance scientifically. This ranges from evaluation of new satellite retrievals, new trace gas and aerosol measurement methods and techniques for source apportionment and emission inventory evaluation, to process studies of deposition, secondary air pollutant formation (gas and particle) and black carbon coating and light absorption.

The 10th International Carbon Dioxide Conference (ICDC10 ) and the 19th WMO/IAEA Meeting on Carbon Dioxide, other Greenhouse Gases and Related Measurement Techniques (GGMT-2017) (ACP/AMT/CP/ESD inter-journal SI)
01 Oct 2017–30 Sep 2018 | Guest editors: M. Heimann, N. Gruber, M. Leuenberger, C. LeQuere, J. Pongratz, C. Prentice, J. Randerson, M. Steinbacher, and C. Zellweger | Information

The International Carbon Dioxide Conference (ICDC) is the single largest conference organized by the global research community every four years to present the latest scientific findings on the science of the carbon cycle and its perturbation by human activities. The ICDC10 in 2017 is the 10th anniversary conference. It covers fundamental science advancement and discovery, the generation of policy relevant information, and observational and modeling approaches. ICDC10 brings together scientists from different disciplines to work towards an integrated view on the global cycle of carbon in the Earth system.

The main themes of the conference are as follows:

  1. The contemporary carbon cycle
    • Trends, variability, and time of emergence of human impacts
    • Emerging approaches and novel techniques in observations
  2. The paleo-perspective: patterns, processes, and planetary bounds
  3. Biogeochemical processes
    • Process understanding and human impacts
    • Coping with complexity: from process understanding to robust models
  4. Scenarios of the future Earth and steps toward long-term Earth system stability

GGMT-2017 is a key conference on measurement techniques for accurate observation of long- lived greenhouse and related gases, their isotopic composition in the atmosphere relevant for climate change, and global warming research findings. The biannual meeting, known as the WMO/IAEA Meeting of Experts on Carbon Dioxide, Other Greenhouse Gases and Related Tracer Measurement Techniques, is to be held for the 19th time in 2017.

Main topics:

  • Developments of the GHG networks
  • CO2 observations (measurement techniques and calibration)
  • Non-CO2 observations (measurement techniques and calibration)
  • Isotope measurement and calibration
  • Emerging techniques
  • GHG standards and comparison activities
  • Integration of observations, data products and policy

The special issue is open for papers that emerged from ICDC10 and GGMT -2017 conference contributions.

Regional transport and transformation of air pollution in eastern China
24 Mar 2016–15 Mar 2018 | Guest editors: T. Zhu, Y. Zhang, J. Chen, D. Heard, Z. Li, L. Molina, L. Morawska, D. Parrish, H. Su, and R. Zhang | Information

Eastern China is experiencing serious air pollution. North China Plain, including the megacities Beijing and Tianjin, is the region with the worst air pollution in China, followed by cities such as Shanghai, Nanjing and Wuhan along the Yangtze River basin. To understand the transport and transformation processes of atmospheric pollution, as well as to evaluate the impacts of aerosol on climate and cloud formation, many studies have been conducted in eastern China. As a follow up to CAREBEIJING 2006/2007/2008, the CAREBEIJING-NCP (Campaigns of Air Pollution Research in Megacity Beijing and North China Plain) and the Yangtze River campaign were conduced in 2013, 2014 and 2015 to address critical scientific questions, such as HOx chemistry, atmospheric oxidative capacity, chemical composition of fine particles, formation processes of new particle and secondary aerosol, multiphase reaction on the surface of fine particles, optical and hygroscopic properties of aerosol and their implications for air quality and climate impacts. The major findings from studies in this region will be reported in this special issue.

NETCARE (Network on Aerosols and Climate: Addressing Key Uncertainties in Remote Canadian Environments) (ACP/AMT/BG inter-journal SI)
23 Feb 2016–28 Feb 2019 | Guest editors: L. Bopp, K. Carslaw, D. J. Cziczo, and L. M. Russell | Information

NETCARE (Network on Aerosols and Climate: Addressing Key Uncertainties in Remote Canadian Environments) is a large research network focusing on aerosol–cloud–climate interactions. While Canadian-based, it operates with many international collaborations. It is comprised of scientists working in both atmospheric science and marine biogeochemistry, with particular attention given to a suite of intensive field measurements (with both atmospheric and oceanic components) and model evaluation and development. There are three major research directions within the network: 1. Carbonaceous Aerosol, 2. Arctic Clouds, and 3. Ocean–Atmosphere Interactions. A large amount of the research has an Arctic focus, it being a region especially susceptible to anthropogenic input and experiencing a large degree of biogeochemical change. The website for the network is On the website, there is more information on research activities, field campaign details, modeling activities, data products, and personnel.

Water vapour in the upper troposphere and middle atmosphere: a WCRP/SPARC satellite data quality assessment including biases, variability, and drifts (ACP/AMT/ESSD inter-journal SI)
10 Feb 2016–01 Apr 2018 | Guest editors: J. Russell, K. Rosenlof, S. Buehler, and G. Stiller | Information

The Water Vapour Phase II (WAVAS II), a SPARC activity, started in 2008 (SPARC Newsletter No. 30 (2008) p. 16: SPARC Water Vapour Initiative, by C. Schiller et al.). The activity includes satellite assessment and in situ comparison components. This international activity encompasses:

  1. Providing a quality assessment of upper tropospheric to lower mesospheric satellite records since the early 1990s
  2. Providing, as far as possible, absolute validation against ground-truth instruments
  3. Assessing inter-instrument biases, depending on altitude, location, and season
  4. Assessing the representation of temporal variations on various scales
  5. Including data records on isotopologues
  6. Providing recommendations for usage of available data records and for future observation systems

The main objective of WAVAS II is to assess and extend our knowledge and understanding of measurements of the vertical distribution of water vapor in the upper troposphere and middle atmosphere (UT/MA), where water has small concentrations, but significant radiative impact. This is a follow-up of the SPARC WAVAS activity, whose report was published in 2000 (SPARC Report No. 2 (2000) Upper Tropospheric and Stratospheric Water Vapour. D. Kley, J.M. Russell III, and C. Philips (eds.). WCRP-113, WMO/TD - No. 1043). Information gained from this activity will improve our ability to estimate long-term changes with associated uncertainties in UT/MA water as well as make recommendations as to what data would be most valuable for model validation and how such data should be used.

Papers will be accepted for this special issue according to the following guidelines, independent if they originate from the WAVAS II activity or other activities.

Guidelines for submissions:

  • papers covering existing UT/MA satellite water vapour measurements;
  • papers discussing comparisons of UT/MA satellite measurements, including discussion of quantities derived from these measurements, such as seasonal cycles, estimates of transport, or estimates of drifts, trends and variability;
  • papers discussing merging of water vapour measurements will be considered, although this topic is not specifically part of the WAVAS-II activity;
  • model papers that incorporate the datasets discussed and the uncertainty estimates resulting from the WAVAS-II activity will also be considered for inclusion.

The SPARC Reanalysis Intercomparison Project (S-RIP) (ACP/ESSD inter-journal SI)
02 Feb 2016–31 Dec 2018 | Guest editors: P. Haynes, G. Stiller, and W. Lahoz | Information

The climate research community uses reanalyses widely to understand atmospheric processes and variability in the middle atmosphere, yet different reanalyses may give very different results for the same diagnostics. For example, the global energy budget and hydrological cycle, the Brewer–Dobson circulation, stratospheric vortex weakening and intensification events, and large-scale wave activity at the tropical tropopause are known to differ among reanalyses.

The Stratosphere–troposphere Processes And their Role in Climate (SPARC) Reanalysis Intercomparison Project (S-RIP) is a coordinated activity to compare reanalysis data sets with respect to a variety of key diagnostics. The objectives of this project are

  1. to understand the causes of differences among reanalyses;
  2. to provide guidance on the appropriate usage of various reanalysis products in scientific studies;
  3. to contribute to future improvements in the reanalysis products by establishing collaborative links between the reanalysis centres and the SPARC community.

The project focuses predominantly on differences among reanalyses (although studies that include operational analyses are welcome and studies comparing reanalyses with observations are encouraged), with an emphasis on diagnostics in the upper troposphere, stratosphere and mesosphere. This special issue serves to collect research with relevance to S-RIP in preparation for the publication of the S-RIP report in 2018. Although participation in S-RIP is not a prerequisite for submission to this special issue, authors contributing to this collection are encouraged to consider contributing to the preparation of the S-RIP report.

ML-CIRRUS – the airborne experiment on natural cirrus and contrail cirrus in mid-latitudes with the high-altitude long-range research aircraft HALO (ACP/AMT inter-journal SI)
15 Nov 2015–31 Dec 2017 | Guest editors: C. Voigt, E. Jensen, D. Baumgardner, U. Schumann, R.-S. Gao, and O. Möhler | Information

The ML-CIRRUS mission deployed the novel high-altitude long-range research aircraft HALO to get new insights into the nucleation, life cycle and climate impact of natural cirrus and anthropogenic contrail cirrus. The ML-CIRRUS mission with the G5 research aircraft HALO combined an in situ/remote sensing payload including a suite of direct state-of-the-art cloud instruments and a novel aerosol and ice residual, trace gas and radiation instrumentation as well as a high-spectral-resolution water vapor lidar. The aircraft observations were assisted by remote sensing observations from satellite and ground and by numerical simulations to predict cirrus and contrail cirrus occurrence. ML-CIRRUS will provide a comprehensive data set on natural cirrus and aircraft-induced cloudiness for cloud process studies and climatological considerations.

Twenty-five years of operations of the Network for the Detection of Atmospheric Composition Change (NDACC) (AMT/ACP/ESSD inter-journal SI)
10 Nov 2015–30 Apr 2017 | Guest editors: V.-H. Peuch, G. Brasseur, C. Zehner, N. Harris, H. Maring, W. Lahoz, and G. Stiller | Information

The international Network for the Detection of Atmospheric Composition Change (NDACC) officially started in 1991; its original name was Network for the Detection of Stratospheric Change (or NDSC). Since then, the network has grown and its scope has expanded to also encompass tropospheric and climate-related research.

This special issue will commemorate 25 years of NDACC/NDSC operations and research, and it will highlight the current status of the network as well as its perspectives and challenges for the future.

Chemistry–Climate Modelling Initiative (CCMI) (ACP/AMT/ESSD/GMD inter-journal SI)
23 Oct 2015–30 Sep 2018 | Guest editors: B. N. Duncan, A. Gettelman, P. Hess, G. Myhre, and P. Young | Information

IGAC/SPARC CCMI ( consists of a wide range of researchers, including chemistry-climate modelers, observationalists, and data analysts who are investigating the historical and projected evolution of stratospheric and tropospheric composition and chemistry, including the links between those domains, and the feedbacks with the physical climate. A current CCMI activity is a series of hindcast model simulations in support of upcoming ozone and climate assessments. The goal is to quantify how well the models can reproduce the past behavior (climatology, trends and interannual variability) of tropospheric and stratospheric ozone, other oxidants, and more generally chemistry-climate interactions, as well as to understand processes that govern these interactions. An emphasis is placed on observational based evaluation of model output, including model processes. A future CCMI activity will be to analyze projections of the future evolution of tropospheric and stratospheric ozone.

Advanced Global Navigation Satellite Systems tropospheric products for monitoring severe weather events and climate (GNSS4SWEC) (AMT/ACP/ANGEO inter-journal SI)
01 Nov 2015–31 May 2018 | Guest editors: G. Vaughan, J. Jones, S. de Haan, E. Pottiaux, O. Bock, R. Pacione, and R. Van Malderen | Information

Since 1990, signals from global positioning system (GPS) satellites have been recorded by networks worldwide. From these GPS observations the zenith total delay (ZTD) can be computed. Using surface measurements of pressure and temperature, these ZTD values can be turned into water vapour amount and used for atmospheric research. The main aim of the COST action ES1206 “Advanced Global Navigation Satellite Systems tropospheric products for monitoring severe weather events and climate” (GNSS4SWEC) is to coordinate the research and the development of new, advanced tropospheric products derived from GNSS signal delays, exploiting the full potential of multi-GNSS (GPS, GLONASS and Galileo) water vapour estimates on a wide range of temporal and spatial scales, from real-time monitoring and forecasting of severe weather to climate research. The potential impacts of this work are great: improved severe weather forecasting, leading to a decreased risk to life and national infrastructure; improvement of climate projections also has major global significance. In addition the action will promote the use of meteorological data in GNSS positioning, navigation, and timing services.

The main topics envisioned in the special issue include the following:

  • The development of advanced and new GNSS tropospheric products related to
    • multi-GNSS constellation signals for water vapour remote sensing,
    • water vapour anisotropy (horizontal gradients, satellite slant delays, tomography, etc.),
    • real-time/ultra-fast water vapour remote sensing in support of nowcasting ,
    • improvement of the temporal and spatial resolution capability of GNSS water vapour remote sensing.
  • The exploitation of these products in numerical weather prediction (NWP) and nowcasting, such as
    • the development of new initialization/assimilation methods in NWP,
    • the development of forecasting tools (water vapour maps, convective indexes, alarm systems, etc.) for nowcasting and severe weather events.
  • The assessment of these GNSS tropospheric products (see first point) derived from a common benchmark reference data set.
  • The assessment of the standardized methods/tools for NWP/nowcasting (see second point) based on the GNSS products built on the benchmark data set.
  • Exploiting re-analysed/reprocessed GNSS tropospheric products for climate studies:
    • comparison/assimilation in the regional/ global climate models,
    • comparisons with other in-situ, ground-based and satellite water vapour retrievals,
    • development and assessment of homogenization methods for GNSS-based product time series,
    • analysing the variability and trends in GNSS-based water vapour retrievals.
  • Establishment of new GNSS analysis centres for monitoring the atmosphere.

Submissions of papers dealing with broader GNSS4SWEC objectives are also encouraged:

  • synergy between GNSS and GNSS radio occultation (RO),
  • monitoring the other components of the hydrological cycle (soil moisture, snow cover, terrestrial water storage) with GNSS.

Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) (ACP/BG/AMT/GMD/GI inter-journal SI)
01 Jun 2015–31 May 2018 | Guest editors: J. Allan, T. Petäjä, T. Karl, M. A. Silva Dias, and T. Garrett | Information

Observations and modelling of the Green Ocean Amazon (GoAmazon2014/5): the GoAmazon2014/5 campaign sought to quantify and understand how aerosol and cloud life cycles in a particularly clean background in the tropics were influenced by pollutant outflow from a large tropical city. The project addressed the susceptibility of cloud–aerosol–precipitation interactions to present-day and future pollution in the tropics. The experiment took place in central Amazonia from 1 January 2014 to 31 December 2015, including intensive operating periods and aircraft in the wet and dry seasons of 2014.

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

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)
20 Mar 2015–30 Apr 2019 | Guest editors: M. Kulmala, L. Ganzeveld, and G. Fisch | Information

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)
17 Mar 2015–19 May 2017 | 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 | More information

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
01 Mar 2015–01 Dec 2017 | Guest editors: F. Dentener, S. Galmarini, C. Hogrefe, G. Carmichael K. Law, and B. R. D. Denby | More information

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)
16 Feb 2015–28 Feb 2018 | Guest editors: B. Weinzierl, U. Wandinger, C. Flamant, C. Hoose, C. Ryder, and J. Schwarz | Information

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
01 Feb 2015–31 Jan 2018 | Guest editors: W. Birmili, D. Covert, K. Kai, and T. Takamura

The Modular Earth Submodel System (MESSy) (ACP/GMD inter-journal SI)
08 Oct 2014–indefinite | Coordinator: P. Jöckel | Papers are handled by ACP co-editors | Information

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)
02 Oct 2014–30 Sep 2017 | Guest editors: U. Lohmann, N. Vaughan, L. M. Russell, B. Kravitz, and H. Wang | Information

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)
26 Sep 2014–30 Sep 2017 | Guest editors: W. T. Sturges, L. M. Russell, C. Robinson, L. Bopp, H. Wernli, and M. Krämer

Data assimilation in carbon/biogeochemical cycles: consistent assimilation of multiple data streams (BG/ACP/GMD inter-journal SI)
01 Jan 2015–30 Apr 2017 | Guest editors: M. Scholze, M. Heimann, V. Brovkin, C. Sierra, and C. Gerbig

Ten years of Ozone Monitoring Instrument (OMI) observations (ACP/AMT inter-journal SI)
17 Mar 2015–31 Mar 2017 | 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 | More information

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.

HD(CP)2 Observational Prototype Experiment (ACP/AMT inter-journal SI)
01 Mar 2014–30 Jun 2017 | Guest editors: S. Buehler and H. Russchenberg | Information

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)
01 Jan 2014–31 Jul 2018 | Guest editors: H. Coe, K. Longo, M. Andreae, S. Martin, and G. Myhre | Information

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)

20 Dec 2013–31 Dec 2018 | Guest editor: G. Grell | Information

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)
18 Dec 2013–31 Dec 2018 | Guest editors: J. Abbatt, A. Bertram, D. J. Cziczo, and B. Ervens | Information

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).

Study of Ozone, Aerosols and Radiation over the Tibetan Plateau (SOAR-TP) (ACP/AMT inter-journal SI)
31 Oct 2013–31 Dec 2017 | Guest editors: R. Sander, H. Su, T. Wagner, T. Wang, Y. Cheng, and X. Xu | Information

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)​
14 Oct 2013–31 Jul 2017 | Guest editors: N. Mihalopoulos, W. Lahoz, X. Querol, C. Reeves, F. Dulac, O. Dubovik, J.-L. Attie, M. Beekmann, and E. Gerasopoulos | Information

The Chemistry and Aerosol Mediterranean Experiment (ChArMEx) special issue will be simultaneously presented in the ACP and AMT journals. It aims at gathering experimental and modelling contributions to the field of atmospheric chemistry in the Mediterranean region and its impacts on regional air quality and climate, both in the recent past, present and future decades. It addresses natural and anthropogenic emissions of tropospheric reactive species, source apportionment, chemical transformations, transport processes, atmospheric deposition, aerosol optical properti

Surface Ocean Aerosol Production (SOAP) (ACP/OS inter-journal SI)
01 Jul 2013–31 Jul 2017 | Guest editors: C. Law, M. Harvey, M. Smith, P. Quinn, N. Harris, and M. Hoppema | Information

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.

Interactions between climate change and the Cryosphere: SVALI, DEFROST, CRAICC (2012–2016) (TC/ACP/BG inter-journal SI)
19 Jun 2012–30 Jun 2017 | 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

HCCT-2010: a complex ground-based experiment on aerosol-cloud interaction
25 Oct 2011–31 Dec 2017 | Guest editors: G. McFiggans, M. C. Facchini, C. George, and H. Herrmann

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