Aerosol-Cloud Interactions - A Directed Programme to Reduce Uncertainty in Forcing (ACID-PRUF) through a Targeted Laboratory and Modelling Programme
Lead Research Organisation:
University of Leeds
Department Name: School of Earth and Environment
Abstract
Aerosol particles act as sites for cloud droplet and ice particle formation. Cloud properties can be perturbed through the addition of aerosol particles into the atmosphere from anthropogenic and natural processes. This addition influences cloud microphysical properties, and subsequently affects cloud dynamics and thermodynamics, and the way the cloud interacts with radiation. The Earth's radiation budget is very greatly affected by clouds, and human-induced changes to the particle loading affecting them, known as indirect effects, are large and highly uncertain. A large part of this uncertainty is the result of poor knowledge of the fundamental aerosol and cloud properties and processes, leading to their poor representation in models. A programme of research is proposed here to i) directly investigate these processes in the laboratory, ii) evaluate the sensitivity of climate relevant parameters to the studied processes, iii) interpret the laboratory studies with detailed model investigations and iv) to incorporate and test new descriptions of the studied processes in cloud-scale and, where possible, global scale models. The programme will thereby reduce the uncertainty in estimates of radiative forcing and climate feedbacks relating to aerosol and cloud processes. The studies are split into those affecting warm clouds (those containing only liquid droplets) and those affecting clouds containing ice particles. The programme brings together an interdisciplinary team of researchers with expertise in 'warm' and 'cold' cloud and aerosol processes combining laboratory and multiscale modelling activities to deliver the improved predictive capability. The 'warm' laboratory work focuses on two major aspects i) the rate at which water is taken up by growing aerosol particles as they become cloud droplets (or 'activate) and ii) the ability of aerosol particles of various compositions to act as seeds for cloud droplets. These studies use a number of techniques including single particle optical levitation and investigations in a large photochemical chamber coupled to a large number of chemical and physical probes of ensembles of particles formed in simulated atmospheric chemical processes. The 'cold' work uses a similar coupling of a large, well-instrumented cloud chamber experiments and single particle levitation studies. The chambers used in both aspects will be coupled to investigate the impacts of aerosol transformation conditions on warm and cold cloud formation, using the instrumental payload from both chambers. A range of detailed models will be used to explicitly describe the processes by which aerosol particles interact with increasing relative humidity and reducing temperature to form cloud droplet and ice crystals and to their properties. The processes and properties will be represented in dynamical frameworks to predict the interactions between aerosols and clouds and their radiative effects at cloud resolving scales and radiative forcing of some of the investigated properties on global radiative forcing and feedbacks. The sensitivity of climate relevant parameters to the fundamental parameters investigated in the laboratory programme and their improved quantification will be evaluated using a simplified model 'emulator'.
Organisations
Publications
Murray B
(2015)
The crystal structure of ice under mesospheric conditions
in Journal of Atmospheric and Solar-Terrestrial Physics
O'Sullivan D
(2015)
The relevance of nanoscale biological fragments for ice nucleation in clouds.
in Scientific reports
O'Sullivan D
(2014)
Ice nucleation by fertile soil dusts: relative importance of mineral and biogenic components
in Atmospheric Chemistry and Physics
Park J
(2020)
Environmental Controls on Tropical Sea Breeze Convection and Resulting Aerosol Redistribution
in Journal of Geophysical Research: Atmospheres
Peace A
(2020)
Effect of aerosol radiative forcing uncertainty on projected exceedance year of a 1.5 °C global temperature rise
in Environmental Research Letters
Price H
(2014)
Quantifying water diffusion in high-viscosity and glassy aqueous solutions using a Raman isotope tracer method
in Atmospheric Chemistry and Physics
Price HC
(2015)
Water diffusion in atmospherically relevant a-pinene secondary organic material.
in Chemical science
Regayre L
(2018)
Aerosol and physical atmosphere model parameters are both important sources of uncertainty in aerosol ERF
in Atmospheric Chemistry and Physics
Regayre L
(2020)
The value of remote marine aerosol measurements for constraining radiative forcing uncertainty
in Atmospheric Chemistry and Physics
Renbaum-Wolff L
(2013)
Viscosity of a-pinene secondary organic material and implications for particle growth and reactivity.
in Proceedings of the National Academy of Sciences of the United States of America
Sanchez-Marroquin A
(2020)
Iceland is an episodic source of atmospheric ice-nucleating particles relevant for mixed-phase clouds.
in Science advances
Sengupta K
(2021)
A global model perturbed parameter ensemble study of secondary organic aerosol formation
in Atmospheric Chemistry and Physics
Umo N
(2015)
Ice nucleation by combustion ash particles at conditions relevant to mixed-phase clouds
in Atmospheric Chemistry and Physics
Watson-Parris D
(2020)
Constraining Uncertainty in Aerosol Direct Forcing
in Geophysical Research Letters
Wellmann C
(2020)
Comparing the impact of environmental conditions and microphysics on the forecast uncertainty of deep convective clouds and hail
in Atmospheric Chemistry and Physics
Whale T
(2015)
A technique for quantifying heterogeneous ice nucleation in microlitre supercooled water droplets
in Atmospheric Measurement Techniques
Whale TF
(2015)
Ice Nucleation Properties of Oxidized Carbon Nanomaterials.
in The journal of physical chemistry letters
Whale TF
(2018)
The enhancement and suppression of immersion mode heterogeneous ice-nucleation by solutes.
in Chemical science
Whale TF
(2017)
The role of phase separation and related topography in the exceptional ice-nucleating ability of alkali feldspars.
in Physical chemistry chemical physics : PCCP
Description | A detailed model that calculates physical processes in clouds has been used to test whether barriers to the uptake of water vapour onto cloud droplets (described by the accomodation coefficient) makes any difference to the production and development of ice and precipitation particles. Values from the literature were used while waiting for laboratory results being produced in another part of the grant. It was found that the ice and precipitation production and growth was not sensitive to a wide range of values of the accomodation coefficient. |
Exploitation Route | Improved forecasts of all processes involving clouds and global climate models. The results will be used in numerical weather prediction models and global climate models. |
Sectors | Environment |