2016 AMS Ninth Symposium on Aerosol-Cloud-Climate Interactions Abstracts

Cloud Adjustments to the Presence of Shortwave-Absorbing Aerosols and Large-scale Feedbacks

Session Co-Chairs: Paquita Zuidema (University of Miami) and Yan Feng (Argonne National Laboratories)

Session Description: Clouds adjust to the presence of absorbing aerosols in myriad ways, depending on the large-scale meteorological conditions, the relative vertical location of the clouds and aerosols and aerosol properties. The cloud responses differ from those to scattering-only aerosols and can include both increases or decreases in cloud cover and changes in precipitation susceptibility. Resulting changes in the atmospheric temperature structure, including from surface dimming, in turn affect regional circulation and precipitation patterns. This session invites both modeling and observational presentations, from cloud-scale understandings to large-scale circulation and moisture feedback. We invite studies representing the full range of cloud and absorbing aerosol regimes, including ice clouds, and from recent field experiments. Those with a focus on quantifying the aerosol absorption are also encouraged.

Aerosol Impacts on Warm Low Clouds

Session Co-Chairs: Rob Wood (University of Washington) and Alison Nugent (NCAR)

Session Description: Warm low cloud systems are sensitive to changes in aerosol properties, which modulate cloud microphysical properties and can influence precipitation formation and cloud scale dynamics. In addition, absorbing aerosols can modulate the thermodynamic environment experienced by clouds. Ultimately, these controls may alter low cloud radiative properties and climate. Aerosol particles, in turn, are impacted by cloud processes. Together, these interactions result in a coupling of the aerosol-cloud system whose coupling strength is highly variable and is poorly understood in terms of basic process understanding. Correctly representing this coupling has proven challenging to represent in large-scale models. In this session, we invite presentations on all topics related to aerosol-cloud coupling in warm low clouds, including those addressing basic physical understanding, the quantification of aerosol indirect effects, cloud effects on aerosols, and the coupling between aerosols and boundary layer turbulence, cloud dynamics, and precipitation.

Aerosol-Deep Convection Interactions

Session Co-Chairs: Sue van den Heever (Colorado State University) and Adele Igel (Colorado State University)

Session Description: Understanding the interactions between aerosol particles and deep convective clouds is challenging for a number of reasons. Aerosol particles influence the microphysical properties, latent heat release, and ultimately the dynamics of these storms. Characteristics of the anvils, hydrometeors, surface precipitation, and cold pools can be significantly altered as a result. Deep convective clouds are in turn important for removing and redistributing aerosol particles in the atmosphere. For this session, we seek presentations on interactions between aerosols and all types of isolated and organized deep convection in the tropics and midlatitudes, including mesoscale convective systems and hurricanes. Papers focusing on aspects of aerosol-deep convection interactions such as precipitation, cloud microphysical and radiative properties, cold pools, and storm dynamics are welcomed. Papers on deep convective transport of aerosols and dust are also strongly encouraged.

Aerosol-cloud interactions in regional and global climate models: Uncertainties and discrepancies between models and observations

Session Co-Chairs: Xiaohong Liu (University of Wyoming)

Session Description:
Estimation of “effective” radiative forcing due to aerosol-cloud interactions from climate models is associated with large uncertainty. There are also large discrepancies between models and observations in their estimations of aerosol-cloud interactions. This session solicits presentations targeting these challenges, including but not limited to, representation of aerosol-cloud interactions in regional and global climate models; understanding of model deficiencies in estimating aerosol-cloud interactions; and new methodologies of facilitating the comparisons between models and observations. We invite studies of aerosol interactions with different types of clouds (e.g., low stratiform clouds, mixed-phase clouds, convective clouds, and ice clouds) using different scales of models.

Observations of Aerosol/Trace Gases, Clouds, Precipitation, and Radiation from DOE Atmospheric Radiation Measurement (ARM) Climate Research Facility (Joint with the 19th Conference on Atmospheric Chemistry; the 9th Symposium on Aerosol-Cloud-Climate interactions to host)

Session Co-Chairs: Jiwen Fan (Pacific Northwest National Laboratory), Gijs de Boer (University of Colorado), Jim Mather (Pacific Northwest National Laboratory), Andrew Vogelmann (Brookhaven National Laboratory), Robert Wood (University of Washington), Jian Wang (Brookhaven National Laboratory)

Session Description: This is a named session for the US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility. ARM provides the climate research community with strategically located observatories and coordinated aerial measurements designed to provide in-situ and remotely-sensed measurements to improve understanding of clouds and aerosols and their connection to the Earth’s energy budget. This understanding ultimately targets improved characterization of relevant processes in climate and earth system models. The session will include invited speakers to provide overviews of ARM capabilities in advancing our understanding of aerosol, cloud, precipitation and radiation, as well as speakers positioned to provide unique insights into critical advances spurred on by ARM observations. We solicit papers spanning instrumentation advancements and limitations, observational strategies and errors/uncertainties, and observational analyses to improve process understanding and model/parameterization evaluation. Papers demonstrating observational gaps in improving model parameterization and forecast capabilities and novel integration of observations and models are particularly welcome.

Impacts of Aerosol-Cloud Interactions on Radiation

Session Co-Chairs: Jun Wang (University of Nebraska) and Zhibo Zhang (UMBC)

Session Description: Aerosol-cloud interactions are considered as one of the largest uncertainties in the estimate of climate forcing by human activities. While numerical mechanisms and processes associated with aerosol-cloud interactions have been proposed, their climate significance ultimately has to be assessed from a radiative energy point of view. This session seeks presentations reporting progress in understanding the change of cloud radiative properties and radiative effects as a result of aerosol impact on cloud microphysics and lifetime, change of aerosol radiative effects by surrounding (and underlying) clouds, and novel measurement and modeling techniques to quantify the impacts of aerosol-cloud interactions on radiation.

Soil Dust Lofting, Transport, and Warm and Cold Cloud Interactions

Session Co-Chairs: Ottmar Moehler (KIT)

Session Description:
Dust from both deserts and more vegetated areas contributes a major fraction of the atmospheric aerosol and has a variety of sources, compositions and impacts. The goal of this session is to bring together scientists from different disciplines working on the characterization, emission, atmospheric transport, chemical transformation and impact of dust from desert, vegetated or agricultural areas. We invite and welcome contributions from the general areas (1) speciation and characterization of the mineralogy, organic content and other constituents of dust sampled from source regions or directly from the atmosphere, (2) emission fluxes, transport and chemical transformation of dust in the atmosphere, and (3) cloud and climate impacts of atmospheric dust, including optical properties, CCN activation, and heterogeneous ice nucleation behaviors.

Polar Clouds and Climate (Joint Session with Polar Meteorology and Oceanography, who will host)

Session Co-Chairs: Ryan Fogt (Ohio University)

Session Description: Clouds regulate radiative and precipitation fluxes in polar regions, and thus control fundamental aspects of the climate system such as energy budgets, air-sea exchange, and sea level. Cloud-aerosol interactions influence polar cloud radiative impacts and precipitation efficiencies. Polar clouds, precipitation, and aerosol processes are changing in a warming world and new observations and model simulations are supporting and challenging existing paradigms. Sample topics based on observational and/or modeling studies for this session include: How do polar clouds influence radiative fluxes over sea ice and ice sheets? How much precipitation falls in polar regions? What processes control polar cloud-aerosol-precipitation interactions? What are the sources of aerosols, especially cloud condensation nuclei and ice nuclei, at high latitudes? What is the importance of super-cooled liquid cloud water for the climate system? In sum, presentations on all aspects of polar clouds, precipitation, and aerosols at high latitudes are solicited for this session.

Themed Joint Session (with 19ATCHEM): Grand Challenges in Observing Aerosol-Cloud-Climate Interactions

Session Co-Chairs: Sonia Kreidenweis (Colorado State University) and Jiwen Fan (Pacific Northwest National Laboratory)

Session Description: We invite contributions discussing the greatest observational needs to advance understanding of aerosol-cloud-climate interactions. Papers addressing the ways in which observations can be used to evaluate modeling studies of aerosol impacts on clouds and climate, and papers discussing processes within numerical models that could be better represented via insights from new observational strategies, are also welcomed.