Aerosols and Climate

Aerosols and Climate
Copyright
Symbols
Contributors
Acknowledgments
Acronyms and abbreviations
Introduction
What is aerosol and why is it important for climate?
Aims and scope of the book
Terminology, symbols, and units
References
Aerosol in the climate system
The historical development of our understanding of aerosol effects on climate
Evidence for the effects of aerosol on climate
Energy balance of the climate system
Energy flows and the effects of aerosol
Perturbation of energy flows
Radiative forcing and subsequent atmospheric adjustments
Radiative forcing agents
Radiative forcing and climate response
Aerosol radiative forcing
Effects of aerosol on atmospheric radiation
Definition of aerosol radiative forcing and its components
The magnitude and distribution of aerosol radiative forcing
The magnitude of aerosol radiative forcing
The distribution of aerosol radiative forcing
Climate response to changes in aerosol
Aerosol forcing efficacy
Spatial patterns of climate response
Effects on the hydrological cycle and precipitation
References
Aerosol in the Earth system
Introduction to land and ocean productivity and biogeochemistry
Land productivity and biogeochemistry
Human impacts on land productivity and biogeochemistry
Ocean productivity and biogeochemistry
Controls on ocean productivity
Human impacts on ocean productivity
Aerosol effects on land and ocean biogeochemistry
Aerosol deposition effects on terrestrial ecosystems
Aerosol deposition effects on ocean ecosystems
Aerosol deposition effects on freshwater aquatic ecosystems
Effects of aerosol physical climate changes on land and ocean biogeochemistry
Aerosol sources and deposition to the land and oceans
Reactive nitrogen sources and deposition to the land and oceans
Iron sources and deposition to the oceans
Phosphorus sources and deposition to the land and ocean
Other aerosols and their sources and deposition
Effects of climate change and land use on natural aerosol emissions
Dimethyl sulfide emissions under climate change (CLAW hypothesis)
Desert dust changes across the anthropocene
Wildfire and open fire changes across the anthropocene
Soil nitrogen precursor emissions
Biogenic volatile organic compounds and particulate emissions from vegetation
Sea spray responses to climate change
Modeling
Status of aerosol-biogeochemistry-climate feedbacks in Earth system models
Magnitude of aerosol biogeochemistry feedbacks on the carbon cycle
Magnitude of climate-driven natural aerosol feedbacks
Acknowledgment
References
Global aerosol properties
The aerosol particle size distribution
Definition of particle size distributions
Climate-relevant particles
The global distribution of aerosol particles
Aerosol transport pathways
Spatial distribution of particle mass and number
Particle chemical composition
Spatial variations in the particle size distribution
Small-scale aerosol variability
Global distribution of aerosol precursor gases
Aerosol in the preindustrial atmosphere
References
Aerosol processes
Particle sources, sinks, and lifetime
In-air processes
Emission and formation of aerosol precursor gases
Gas-phase formation of precursor gases
Formation of secondary material within particles
New particle formation (nucleation)
Particle growth by vapor condensation
Coagulation
Dissolution
Water uptake (hygroscopicity)
Particle ageing
Ice-nucleating particles
The behavior of charged particles
Removal of particles by sedimentation and dry deposition
In-cloud processes and aerosol wet removal
Cloud droplet formation
Cloud processing and aqueous-phase chemistry
Vertical transport of gases and aerosol particles in clouds (venting)
Wet removal of particles and gases
Summary of timescales
Knowledge gaps, future challenges, and research directions
References
Aerosol-climate modeling
Historical development of aerosol-climate modeling
Pre-IPCC research contributions to aerosol-climate modeling
Modeling for climate assessments: The IPCC period
The range of models used in aerosol-climate research
The anatomy of an atmospheric model
Processes and parameterizations
Parameterization essentials
The concept of splitting to make calculations tractable and efficient
Representation of clouds and precipitation
Clouds as subgrid components of atmospheric models
Representations of cloud particles
Warm cloud bulk microphysics
Microphysical extensions for ice treatment
Representation of aerosol
The aerosol particle size distribution
Aerosol microphysical processes
Representation of cloud-aerosol interactions
Aerosol activation
Aerosol removal and processing by clouds
Ice- and mixed-phase cloud processes
Representation of radiation interactions with clouds and aerosol
Modeling considerations
Model applications and evaluation
Knowledge gaps, future challenges, and research directions
References
Historical changes in aerosol
Timescales
Glacial-interglacial cycles
From medieval to preindustrial times
Preindustrial to present day
Recent decades: The aerosol instrumental period
Measurements of historical changes
Ice core proxy records
Formation of ice archives
Sampling and analyzing ice archives
Ice core chronologies
Interpreting aerosol ice core records
Peat bog, lake and ocean sediment proxy records
Peat bog records
Lake and ocean sediments
Deposition and surface in situ aerosol measurements
Visibility, radiation, and optical properties
Other methods
Historical changes in aerosol
Volcanoes (1000-present day)
Natural and anthropogenic aerosols over the industrial period (1750-present day)
Surface radiation and visibility at the Earths surface (1940-present day)
The aerosol instrumental record (1990-present-day)
Modeling
Set-up of historical model simulations
Model-simulated radiative forcing
Knowledge gaps, challenges, and research directions
References
Aerosol and precursor gas emissions
Developing emission inventories
Emissions from industrial activity
History of development
Activity data
Emission processes and emitted sizes of primary particles
Emission factors
Types of industrial sources
Global industrial emission totals
Emissions from the natural world
Terrestrial sources
Forests and vegetation
Fires
Arid environments: Dust from deserts and soils
Volcanoes
Marine sources
Estimating past emissions
Past industrial emissions
Past natural emissions
Future projections of emissions
Economic and social scenarios
Future projections of industrial emissions
Future projections of natural emissions
Modeling
Assumptions
Observational evaluation of emissions
Knowledge gaps, future challenges, and research directions
References
Measurements of ambient aerosol properties
Measurement principles and instruments
Units and particle diameter definitions
Concentration units
Definitions of particle diameter
Size distributions
Uncertainties, limits of detection, and time resolution
Measuring the mass, number, and size of particles
Gravimetric and equivalents
Optical particle detection
Condensation particle counters
Particle size classifiers
Measuring chemical composition
Soluble ions
Mineral dust
Carbonaceous components
Bio-particles
Aerosol mass spectrometry
Measuring new particle formation
Measuring aerosol particle optical properties
Measuring water interactions
Conducting ambient measurements
Sampling points and inlets
Sampling lines and losses
Measurement platforms
Data from in situ measurements
Processing, file formats, and metadata
Aerosol databases
GAW World Data Centre for Aerosols
NOAA ESRL Federated Aerosol Network
IMPROVE
EMEP
ACTRIS
IAGOS
GASSP
Modeling
Sources of error when comparing models and measurements
Sub-grid-scale variability
Measurement data sparsity in space and time
Case studies
Evaluation of global simulations of CCN and implications for cloud droplet formation (Fanourgakis et al. 2019)
Aerosol mass spectrometer constraint on the global secondary organic aerosol budget (Spracklen et al., 2011)
In situ constraints on the vertical distribution of global aerosol (Watson-Parris et al., 2019)
The vertical profile of organic aerosol (Heald et al., 2011)
References
Remote sensing measurements of aerosol properties
Introduction to ultraviolet, visible, and near-infrared aerosol measurements from satellite
Historical development of space-based aerosol remote sensing
Early history
The 1990s
The EOS era
Uses, strengths, and limitations of space-based aerosol remote sensing
The uses of space-based aerosol remote sensing
What remote sensing can and cannot tell us about aerosol
Spatial and temporal coverage: Orbits and swaths
Retrieval techniques
Broad-swath, VNIR imager aerosol retrievals
Visible-near-infrared (VNIR) multi-angle imager aerosol retrievals
VNIR limb sounding aerosol retrievals
UV imager aerosol retrievals
Thermal infrared (TIR) sounder aerosol retrievals
Active sensor aerosol retrievals
Optimal estimation aerosol retrievals
Remote sensing product uncertainty estimates and validation
Statistical and case-study validation approaches
Formal uncertainty estimates
Modeling
Remote sensing information commonly used to constrain models
Challenges with comparing model output to remote sensing products
Remote sensing in reanalyses
References
Aerosol-radiation interactions
Fundamental aspects of aerosol interactions with radiation
Radiation
Scattering
Scattering regimes
Scattering cross section and efficiency factor
Phase function, asymmetry factor, and upscatter fraction
Absorption
Absorption cross section and efficiency factor
Extinction
Optical depth
Single-scattering albedo
Emission
Aerosol and radiative transfer
Factors determining the radiative effect of aerosol-radiation interactions
Optical properties of aerosol particle types
Solar zenith angle
Underlying surfaces
Influence of clouds
Atmospheric temperature and humidity profiles
Rapid adjustments to radiative effects
Radiative effect of aerosol-radiation interactions
Radiative effect efficiency of aerosol types
Aerosol radiative effect in cloud-free conditions
Aerosol radiative effect in cloudy conditions
Aerosol-radiative effect in all-sky conditions
Radiative forcing and effective radiative forcing of aerosol-radiation interactions
Simplified expressions for radiative forcing
Industrial-period changes in aerosol radiative properties
Industrial-period aerosol radiative forcing
Effective radiative forcing
Uncertainty in aerosol-radiation interactions
Aerosol radiative effect
Aerosol radiative forcing
Modeling
Dependence on aerosol representations
Dependence on approximations used in radiative transfer
Model evaluation
References
Aerosol-cloud interactions in liquid clouds
Fundamental aspects of clouds and radiation
The global distribution and bulk properties of clouds
Cloud regimes
Cloud bulk properties
Effect of clouds on solar radiation
Cloud reflectivity
The dependence of solar radiation on cloud properties
Planetary albedo
Effect of clouds on terrestrial radiation
The dependence of longwave radiation on cloud properties
Cloud adjustments
Fundamental aspects of aerosol interactions with clouds
Cloud sources
Turbulence, vertical motion, and adiabatic cooling
Droplet activation
Condensational growth and supersaturation
Cloud sinks
Precipitation formation via warm-rain processes
Cloud evaporation
Observations of aerosol-cloud interactions
In situ observations of cloud properties
Remote sensing of cloud properties
Challenges in observing aerosol-cloud interactions
Determining causality
Assessments of radiative forcing
Approaches for quantifying radiative forcing
Quantifying the anthropogenic aerosol perturbation
Radiative forcing, DeltaFaci
Adjustments and effective radiative forcing, DeltaFacieff
Overall assessment
Modeling
Clouds
Cloud fraction and condensation
Bulk and spectral microphysical schemes
Aerosol-cloud interactions
Droplet activation
Precipitation and evaporation processes
Model evaluation
Research directions
References
Atmospheric and oceanic dynamical responses to changes in aerosol
Fundamental aspects of how aerosol affects climate dynamics
Aerosol radiative forcing
Interactions between different regions and timescales
Responses of global mean temperature and precipitation
Atmospheric responses on regional scales
Tropics
Global monsoon
Asian monsoons
Africa: Sahel drought and recovery
Australia
Tropical storms
Mid-high latitudes
Oceanic responses
Atlantic: Atlantic multi-decadal variability and Atlantic meridional overturning circulation
Pacific: Pacific decadal oscillation
Tropical Pacific: El Niño Southern Oscillation
Indian Ocean
Modeling
Knowledge gaps, future challenges, and research directions
Acknowledgments
References
Aerosol interactions with deep convective clouds
Fundamental aspects of deep convective clouds
Deep convective cloud dynamics
Convective environment, buoyancy, and vertical motions
Entrainment and detrainment
Pressure perturbation fields
Deep convective cloud microphysics
Warm-phase microphysics
Mixed-phase and ice-phase microphysics
Aerosol effects on deep convective clouds
Effects on cloud microphysics
Effects on cloud dynamics
Effects on precipitation
Effects on cloud macrophysical properties and radiation
Aerosol effects on severe storms
Effects on tropical cyclones and mid-latitude cyclones
Effects on mesoscale convective systems (MCSs)
Effects on hail and tornadoes
Effects on lightning
Effects of deep convective clouds on aerosol particles and precursor gases
Vertical transport and scavenging
Cloud processing and aerosol regeneration
Modeling
Modeling aerosol interactions with deep convection at cloud-resolving scales
Features of models at cloud-resolving scales
Bulk and bin microphysics schemes
Significant findings
Modeling aerosol interactions with deep convection using coarse model grids
Features of coarse-resolution models
Significant findings
Knowledge gaps, future challenges, and research directions
Knowledge gaps and challenges
Research directions
Acknowledgments
References
Ice-nucleating particles and their effects on clouds and radiation
The role of heterogeneous ice formation in defining cloud microphysics and radiative properties
Shallow mixed-phase clouds
Convective clouds
Upper tropospheric ice clouds that form in situ
Role of ice-nucleating particles in cloud feedbacks and climate sensitivity
Shallow mixed-phase cloud feedbacks
Deep convection and anvil cirrus cloud feedbacks
In situ cirrus cloud feedbacks
Our physical understanding of heterogeneous ice nucleation
The stochastic nature of nucleation
Site-specific nucleation
Active site requirements in the mixed-phase versus cirrus regimes
The different types of ice-nucleating particles
INP types important in mixed-phase clouds
INP types important for in situ cirrus clouds
Modeling
Modeling ice-nucleating particles
Heterogeneous nucleation in mixed-phase clouds
Ice nucleation in cirrus
Global model simulations of INP effects on mixed-phase clouds
Global model simulations of INP effects on cirrus
Cloud-resolving simulations of INP effects
Knowledge gaps, future challenges, and research directions
Acknowledgments
References
Aerosol processes in high-latitude environments and the effects on climate
Climatic features of the high-latitude regions
Physical characteristics of high-latitude environments
Atmospheric features of high-latitude environments
The mean general circulation
The Arctic dome
Clouds
High-latitude aerosol sources and processes
High-latitude aerosol emissions
Arctic
Antarctica
Long-range transport of aerosol to high latitudes
Arctic
Antarctica
Aerosol processes at high latitudes
New particle formation, growth, and secondary aerosol components
Chemical aging and cloud processing
Aerosol deposition processes
High-latitude aerosol properties and trends
The availability of measurements to define aerosol properties
Aerosol microphysical and chemical properties at the surface-Seasonal cycles
Arctic
Antarctic
Vertical profile of aerosol properties
Arctic
Antarctica
Decadal aerosol trends at high latitudes
Arctic
Antarctica
Aerosol effects on the climate of polar and subpolar regions
Light-absorbing particles on ice and snow
Local atmospheric aerosol-radiation interactions
Local aerosol-cloud interactions
Modeling
Remote aerosol effects
Local aerosol emissions
Long-distance transport of aerosol
Local aerosol-radiation interactions
Local aerosol-cloud interactions
Knowledge gaps, future challenges, and research directions
References
Volcanic emissions, aerosol processes, and climatic effects
Volcanic gas and particle emissions
Passive volcanic emissions
Eruptive volcanic emissions
Volcanic effects on climate
Volcanic aerosol processes, properties, and mechanisms
Aerosol processes and distribution
Aerosol optical depth
Radiative effects and forcing
Climatic response
Forensic volcanology: Records of eruptions and their climatic effects
Eruption chronologies: When, where, and how big
Records of the climatic effects of volcanic eruptions
Modeling
Model simulations of volcanic effects on climate
Model evaluation and confidence in estimated radiative forcings and climate responses
Knowledge gaps, future challenges, and research directions
References
Climate engineering
Background
Stratospheric aerosol climate engineering
Natural stratospheric aerosol processes
Stratospheric aerosol radiative properties
The mechanisms of stratospheric aerosol climate engineering
Sources of evidence
Analogs
Field and laboratory experiments
Effects of stratospheric aerosol climate engineering on climate
Uncertainties and open research questions
Marine cloud brightening
Natural marine aerosol-cloud processes
The mechanisms of marine cloud brightening
Sources of evidence
Analogs
Field experiments
Effects of marine cloud brightening on climate
Uncertainties and open research questions
Practical aspects of climate engineering
Modeling
Representing climate engineering in models
Different ways models can be used
References
Aerosols in climate and air quality policy
Introduction: Why we need to link climate and air quality policies
Historical background
Aerosol particles as pollutants
Particulate matter (PM) air quality guidelines
Effects on human health
Effects on vegetation and crops: Acid deposition and eutrophication
Measurements of PM
Aerosol pollutants and climate change
Comparing short-lived climate forcers (SLCFs) and CO2-Climate metrics
Climate-air quality interaction
Effects of policies related to air quality and climate
Co-benefits and trade-offs
Modeling
Regional and global emission scenarios
Integrated assessment models
References
Index
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W