Periodic Reporting for period 3 - INTEGRATE (An Integrated View on Coupled Aerosol-Cloud Interactions)
Período documentado: 2023-05-01 hasta 2024-10-31
INTEGRATE deals with understanding and describing the interactions between atmospheric aerosol particles, clouds and precipitation. Besides being central for understanding of the fundaments of the Earth’s atmosphere, they represent one of the key uncertainties in climate projections and have also important implications for air quality and health – clouds and precipitation being the most important sinks removing hazardous particulate matter from the atmosphere. Cloud formation processes, specifically 1) the interplay between the phase transitions taking place upon cloud formation; 2) the interactions between atmospheric chemical composition and dynamics; are poorly understood. This hampers the efforts to constrain the impacts clouds have on aerosol populations (albeit known to be both sources and sinks of particles) and the effects changing aerosol populations have on cloud properties. Poor constraints on these coupled aerosol-cloud interactions (ACI) lead to lacking knowledge on the role that clouds play in the climate system, their role in governing air quality in different environments, and the interactions between future air quality and climate change mitigation measures.
INTEGRATE is based on the assumption that a major reason for these uncertainties are inconsistencies and discontinuities in treating 1) the molecular phase transitions from the gas phase to the largest hydrometeors; 2) the interplay between atmospheric chemical composition and atmospheric dynamics; 3) the complex role that clouds play as the main sink of particulate matter, sources of new particles, but also as subjects to changes driven by aerosol particles. INTEGRATE will connect the key pieces together through work in 1) the process scale, focusing on the phase transitions happening within clouds; 2) the cloud scale, focusing on the integration of relevant chemical and dynamic phenomena; 3) the regional and global scales, focusing on interactions between aerosol loadings and clouds in past, present and future climates. INTEGRATE relies of the thesis that fundamental theory should be developed hand-in-hand with the tools used to project air quality changes and climate. Systematic approaches for bridging the gap between the various time and spatial scales involved are the key to achieve this.
The overall objectives of INTEGRATE are therefore (see also Fig. 1):
O1. Bridging key knowledge gaps in the thermodynamics and kinetics of the interactions between aerosol particles, cloud hydrometeors (water and ice) and the gas phase.
O2. Developing computational techniques for describing aerosols and clouds, accounting for detailed chemistry and microphysics coupled to atmospheric dynamics.
O3. Investigating the net interactions between clouds and aerosol populations in the past, present and future climates.
O4. Systematic simplification and scaling of key processes – which are often too complex to represent from first principles in models used for climate projections or air quality studies.
INTEGRATE is based on the assumption that a major reason for these uncertainties are inconsistencies and discontinuities in treating 1) the molecular phase transitions from the gas phase to the largest hydrometeors; 2) the interplay between atmospheric chemical composition and atmospheric dynamics; 3) the complex role that clouds play as the main sink of particulate matter, sources of new particles, but also as subjects to changes driven by aerosol particles. INTEGRATE will connect the key pieces together through work in 1) the process scale, focusing on the phase transitions happening within clouds; 2) the cloud scale, focusing on the integration of relevant chemical and dynamic phenomena; 3) the regional and global scales, focusing on interactions between aerosol loadings and clouds in past, present and future climates. INTEGRATE relies of the thesis that fundamental theory should be developed hand-in-hand with the tools used to project air quality changes and climate. Systematic approaches for bridging the gap between the various time and spatial scales involved are the key to achieve this.
The overall objectives of INTEGRATE are therefore (see also Fig. 1):
O1. Bridging key knowledge gaps in the thermodynamics and kinetics of the interactions between aerosol particles, cloud hydrometeors (water and ice) and the gas phase.
O2. Developing computational techniques for describing aerosols and clouds, accounting for detailed chemistry and microphysics coupled to atmospheric dynamics.
O3. Investigating the net interactions between clouds and aerosol populations in the past, present and future climates.
O4. Systematic simplification and scaling of key processes – which are often too complex to represent from first principles in models used for climate projections or air quality studies.
During the first half of INTEGRATE, we have laid the foundations of the project and paved the way for the expected progress beyond state-of-the-art. We have recruited the core research team and started to put together the key methodologies used. For example, we have designed and assembled a novel container setup for direct observations of cloud and aerosol microphysics. The setup has been applied in the field, and the analysis of the results is ongoing. We have also developed and applied modeling approaches for describing coupled aerosol and cloud microphysics and chemistry, and used them to describe the atmospheric system and interpret laboratory and field observations. We have also developed novel process-based approaches for evaluating climate models.
Our preliminary results so far highlight the importance of 1) understanding the full spectrum of aerosol number size distribution and the relevant dynamic processes for accurate description of ACI; 2) molecular properties such as volatility (but also solubility and surface activity) in determining interactions between clouds and aerosol precursor gases; 3) understanding the role of hydrometeors in scavenging of gases and aerosol constituents together with simultaneous chemical processing - a highly non-linear process which involves many subtelties; 4) process-based evaluation of climate models.
Our preliminary results so far highlight the importance of 1) understanding the full spectrum of aerosol number size distribution and the relevant dynamic processes for accurate description of ACI; 2) molecular properties such as volatility (but also solubility and surface activity) in determining interactions between clouds and aerosol precursor gases; 3) understanding the role of hydrometeors in scavenging of gases and aerosol constituents together with simultaneous chemical processing - a highly non-linear process which involves many subtelties; 4) process-based evaluation of climate models.
If successful, INTEGRATE will open new avenues for 1) fundamental understanding of the physics and chemistry of atmospheric phase transitions; 2) improved climate projections and ultimately better policies for reaching the targets of the Paris agreement; 3) better predictions of factors controlling air quality, hence facilitating the design of better policies to improve the quality of the air we breathe.
Specifically, the expected outcomes and new horizons opening from INTEGRATE include:
1. Improved mechanistic understanding of particle formation vs. scavenging in and near clouds. Microphysical description of cloud hydrometeor growth, coupling water condensation and ice formation with co-condensation of semi-volatile trace species, as well as condensed phase phase-separation. Simple, yet accurate approaches for treating the effects of complex aerosol particles on cloud formation in ambient conditions. Improved understanding of aerosol-cloud interactions and sensitivities in various environments.
2. Improved mechanistic understanding of aerosol and precursor gas removal and generation by clouds and precipitation. Improved estimates on the impacts of aerosol chemical composition and size distribution to the phase, radiative properties and lifetime of clouds. Budgets of aerosols and their precursors in the vicinity of clouds with output that is compatible with present regional (air quality) and global (climate) models. Unique new data set on simultaneous observations of the composition, size distribution and dynamics of aerosol particles, cloud droplets, ice crystals and precipitation at two high-altitude locations. New modeling tools that combine state-of-the-art chemistry and dynamics.
3. Experimental and theoretical strategy for constraining atmospheric removal and deposition processes better. Improvements within atmospheric regional and global models in terms of simulating aerosol-cloud interactions, including new wet scavenging descriptions and aerosol impacts on cloud properties. Quantitative understanding of the key theoretical, observational and modeling aspects contributing to the uncertainty within the radiative forcing caused by aerosol-cloud-climate interactions.
Specifically, the expected outcomes and new horizons opening from INTEGRATE include:
1. Improved mechanistic understanding of particle formation vs. scavenging in and near clouds. Microphysical description of cloud hydrometeor growth, coupling water condensation and ice formation with co-condensation of semi-volatile trace species, as well as condensed phase phase-separation. Simple, yet accurate approaches for treating the effects of complex aerosol particles on cloud formation in ambient conditions. Improved understanding of aerosol-cloud interactions and sensitivities in various environments.
2. Improved mechanistic understanding of aerosol and precursor gas removal and generation by clouds and precipitation. Improved estimates on the impacts of aerosol chemical composition and size distribution to the phase, radiative properties and lifetime of clouds. Budgets of aerosols and their precursors in the vicinity of clouds with output that is compatible with present regional (air quality) and global (climate) models. Unique new data set on simultaneous observations of the composition, size distribution and dynamics of aerosol particles, cloud droplets, ice crystals and precipitation at two high-altitude locations. New modeling tools that combine state-of-the-art chemistry and dynamics.
3. Experimental and theoretical strategy for constraining atmospheric removal and deposition processes better. Improvements within atmospheric regional and global models in terms of simulating aerosol-cloud interactions, including new wet scavenging descriptions and aerosol impacts on cloud properties. Quantitative understanding of the key theoretical, observational and modeling aspects contributing to the uncertainty within the radiative forcing caused by aerosol-cloud-climate interactions.