ISSI team on
“Aerosol-cloud-precipitation-climate
interactions”
Abstract
Increasing concentrations of anthropogenic aerosol particles have an effect on the amount as well as the spatial and temporal distribution of clouds and precipitation affecting the hydrological cycle. The complex interactions between meteorological parameters, aerosols, cloud microphysics and dynamics make it difficult to assess the effect on precipitation change and climate. Due to the uncertainty of the interactions and effects from local to global scale, a coordinated multidisciplinary approach engaging both experimentalists and modellers is timely. The main objective of the ISSI team is to bring together an international multidisciplinary group of scientists from the areas of aerosol physics and chemistry, cloud dynamics, and cloud microphysics to summarize and publish the outcome of a larger workshop that took place in October 2007. The workshop gathered scientists from the various fields and will lead to a joint international research project, under the auspices of two international research programmes, the International Geosphere-Biosphere Programme (IGBP) and the World Climate Research Programme (WCRP). Three ISSI team meetings will summarize and write a science paper of the outcome of the larger workshop, and synthesize and write a planning paper that will serve as a source paper for further work of the established multidisciplinary community. The team will also outline the scientific aims, implementation strategy, timeline and organization of the starting IGBP-WCRP project. In addition, the team will initiate planning of focused coordinated observational and modelling campaigns to study the aerosol-cloud-precipitation interactions.
Scientific rationale
Aerosol particles from natural sources and resulting from human activities are ubiquitous in the atmosphere. The increasing concentrations of anthropogenic aerosols and their precursor gases from a variety of sources (e.g. from vehicles and industry, agriculture, urban land use) are characteristically different from those emitted naturally (Andreae, 2007), have an effect on weather and climate, and pose serious problems to human health, especially in and around highly populated cities.
Clouds play a major role in climate through their direct interactions with solar radiation and also through a variety of indirect effects, for example cloud lifetime, precipitation and energy redistribution. Precipitation replenishes ground water and completes the hydrological cycle and, therefore, changes in either the amounts and/or the spatial and temporal distribution of rainfall will have drastic impacts on climate and on society, especially in the developing countries. Increases or decreases in rainfall in one region could affect rainfall downwind and changes in rainfall distribution can have a strong effect on vast semi arid regions worldwide.
Precipitation is primarily affected by atmospheric dynamics but is also influenced by cloud microphysical processes related to aerosol properties. Among the factors that could contribute to cloud and rain modification are the effects of air pollution from various sources such as urban air pollution and biomass burning, according to the International Aerosol Precipitation Science Assessment Group (IAPSAG Report, 2007). The Working Group I contribution to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report elucidates progress in understanding of the human and natural drivers of climate change, observed climate change, climate processes and attribution, as well as estimates of future change (IPCC, 2007). Anthropogenic aerosols (primarily sulphate, organic carbon, black carbon, nitrate and dust) are estimated to produce a cooling effect due to direct radiative forcing and indirect cloud albedo forcing. These forcings are better understood due to improved in situ, satellite and ground-based measurements and more comprehensive modelling. In spite of the progress, aerosols are the dominant uncertainty in radiative forcing. Therefore, aerosols, clouds and their interaction with climate is still the most uncertain area of climate change and require multidisciplinary coordinated research efforts.
Main objectives
The main aims of the ISSI team are to:
- Organize three ISSI team meetings gathering an international multidisciplinary group of scientists, both experimentalists and modellers, from the areas of aerosol physics and chemistry, cloud dynamics, and cloud microphysics.
- Summarize, write and publish a peer-reviewed science article on the outcome of a larger workshop (October 2007). The article will be submitted as a review article to Nature or Science. The workshop will gather scientists from the various fields and will lead to an IGBP-WCRP level project to start within 18 months.
- Synthesize and write a “white” paper that will serve as a planning paper for joint further work of the established multidisciplinary community. This paper is a position paper to be submitted as a news and views paper to Nature or Science.
- Outline the scientific aims, implementation strategy, timeline and organization of the starting IGBP-WCRP project.
- Initiate planning of focused coordinated observational and modelling campaigns to study the aerosol-cloud-precipitation interactions.
A planning meeting for the larger workshop took place in
The proposed ISSI team consists of representatives from three international research organizations. Two are core projects within the International Geosphere-Biosphere Programme (IGBP): the Integrated Land Ecosystem-Atmosphere Processes Study (iLEAPS) and the International Global Atmospheric Chemistry (IGAC) project. The Global Energy and Water Cycle Experiment (GEWEX) is a project of the World Climate Research Programme (WCRP). Representatives from each project attend the planning meeting in March 2007. This project also links with the Surface Ocean-Lower Atmosphere Study (SOLAS/IGBP). The proposed team members cover the areas of aerosol physics and chemistry, cloud dynamics, and cloud microphysics. In addition to WMO and IUGG, the ISSI Team has links to remote sensing, European Space Agency (ESA), NASA, several projects within the European Union, e.g., European Network of Excellence on Atmospheric Composition Change (ACCENT) and European Integrated Project on Aerosol, Cloud, Climate, Air Quality Interactions (EUCAARI).
Team members
Prof. Meinrat O. Andreae, Max Planck Institute for
Chemistry,
Prof. Thomas Ackerman,
Prof. Sandro Fuzzi, Consiglio Nazionale
delle Ricerche Instituto di Scienze dell'Atmosfera e del Clima CNR, Bologna,
Italy
Prof. Markku
Kulmala, University of Helsinki, Finland
Dr. William Lau, NASA's
Prof. Ulrike Lohmann, ETH Zürich, Institute for Atmospheric and Climate Science
Prof. Colin
O’Dowd, National
Prof. Daniel Rosenfeld, Hebrew
Prof. Graciela
Raga, Universidad Nacional Autónoma de México, México
Dr. Pier Siebesma,
Royal
Prof. Bjorn Stevens, Max Planck Institute for
First ISSI
Team meeting
The first meeting took place in 28-30 January 2008 (agenda below).
Aims of meeting
-finilize as outline for ACPC research agenda
-start writing a paper to Science on ACPC
-plan timetable for “Science Plan and Implementation Strategy” to take to the mother organizations for strategy
Results from ACPC ISSI Team
-the outline for ACPC research agenda was published in iLEAPS Newsletter No. 5 (http://www.ileaps.org/; http://www.ileaps.org/index.php?option=com_docman&task=do&Itemid=115).
-an article was published: M. O. Andreae: Correlation between cloud condensation
nuclei concentration and aerosol optical thickness in remote and polluted regions. Atmos. Chem. Phys. Discuss., 8, 11293–11320, 2008 (www.atmos-chem-phys-discuss.net/8/11293/2008/)
-an article was submitted to Science and sent to in-depth review in the end of May 2008.
-outline and additions for a Science Plan and Implementation Strategy
Second ISSI
Team meeting
The meeting is 7-9 October 2008. The aim of the meeting is to finalize a Science Plan and Implementation Strategy for ACPC to take to mother organizations for strategy.
THE FIRST ISSI TEAM MEETING
“AEROSOL-CLOUD-PRECIPITATION-CLIMATE
INTERACTIONS”
Agenda
Monday, 28 January
9.00-9.20 Welcome and introduction to ISSI
Vittorio Manno
9.20-9.30 ISSI plans on Earth Sciences
Lennart Bengtsson
9.30-10.30 General session
-outline of work for the first ISSI meeting (articles, Science Plan, Implementation Plan)
-planning daily schedule (Monday-Wednesday), division to writing groups
10.30-11.00 Coffee
11.00-12.30 Separate groups’ writing sessions
12.30-13.00 General session to compare groups’ plans
13.00-14.00 Lunch
14.00-15.40 Separate groups’ writing sessions
15.40-16.00 General session to compare groups’ writings
16.00-16.30 Coffee
16.30-17.45 Separate groups’ writing sessions
18.00 Welcome wine at ISSI coffee area
19.00 Dinner
Tuesday, 29 January
9.00-10.30 General session
-status of working group writings
-discussion on ACPC Science Plan, Implementation Plan
10.30-11.00 Coffee
11.00-12.30 Separate groups’ writing sessions
12.30-13.00 General session to compare groups’ plans
13.00-14.00 Lunch
14.00-15.40 Separate groups’ writing sessions
15.40-16.00 General session to compare groups’ writings
16.00-16.30 Coffee
16.30-17.45 Separate groups’ writing sessions
19.00 Dinner
Wednesday, 30 January
9.00-10.30 General session
-outcome of the working groups
-timetable for next steps (submission of articles etc)
-planning of activities
-organization of ACPC, steering committee
-proposal to IGBP and WCRP
10.30-11.00 Coffee
11.00-12.30 Separate groups’ writing sessions
12.30-13.00 General session to compare groups’ plans
13.00-14.00 Lunch
14.00-15.00 General session
-finalization of plans, tasks and timetable before second ISSI meeting
-next ISSI meeting (date)