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Aerosol–Cloud Interaction in Deep Convective Clouds over the Indian Peninsula Using Spectral (Bin) Microphysicsmostly to regional aspects. However, convective clusters embedded in more realistic large-scale conditions over a large area were not investigated. There are very few studies available over the Indian region on aerosol–cloud interaction that investigate the cloud particle size spectra. Extensive aircraft data over India suggested that the effect of aerosol loading and moisture modulates the drop size distribution, which in turn affects ice microphysical processes, especially the processes in the
mostly to regional aspects. However, convective clusters embedded in more realistic large-scale conditions over a large area were not investigated. There are very few studies available over the Indian region on aerosol–cloud interaction that investigate the cloud particle size spectra. Extensive aircraft data over India suggested that the effect of aerosol loading and moisture modulates the drop size distribution, which in turn affects ice microphysical processes, especially the processes in the
1. Introduction The radiative effect of the interactions between atmospheric aerosol and boundary layer clouds remains a large source of uncertainty in estimates of climate sensitivity to anthropogenic forcing (e.g., Boucher et al. 2013 ). Improving forecasts of the fraction of the sky covered by boundary layer clouds is also a priority for solar renewable energy applications ( Perez et al. 2016 ). The need for an improved understanding of aerosol–cloud–radiation variability is clear, but the
1. Introduction The radiative effect of the interactions between atmospheric aerosol and boundary layer clouds remains a large source of uncertainty in estimates of climate sensitivity to anthropogenic forcing (e.g., Boucher et al. 2013 ). Improving forecasts of the fraction of the sky covered by boundary layer clouds is also a priority for solar renewable energy applications ( Perez et al. 2016 ). The need for an improved understanding of aerosol–cloud–radiation variability is clear, but the
distribution, and water solubility), but are also affected by the background climate settings like water vapor abundance and surface albedo. In particular, cloud adjustment effect, which includes both the aerosol–cloud microphysics interactions and the influences of meteorological changes, strongly depends on cloud types and atmospheric conditions ( Fan et al. 2016 ), while the resultant radiative impacts also depend on the altitude where cloud changes occur ( Stephens 2005 ). These complexities make
distribution, and water solubility), but are also affected by the background climate settings like water vapor abundance and surface albedo. In particular, cloud adjustment effect, which includes both the aerosol–cloud microphysics interactions and the influences of meteorological changes, strongly depends on cloud types and atmospheric conditions ( Fan et al. 2016 ), while the resultant radiative impacts also depend on the altitude where cloud changes occur ( Stephens 2005 ). These complexities make
other aerosols, the two major ways dust can alter ambient meteorological conditions, formation and development of cloud, and large-scale circulations are by interacting with 1) radiation (i.e., the dust–radiation interaction, dust-direct effect, or dust-radiative effect) and 2) clouds (i.e., the dust–cloud interaction, dust-indirect effect, or dust-microphysical effect) ( Shi et al. 2014 , Fan et al. 2016 ). Generally, a layer of suspended dust heats the atmosphere within the layer and cools the
other aerosols, the two major ways dust can alter ambient meteorological conditions, formation and development of cloud, and large-scale circulations are by interacting with 1) radiation (i.e., the dust–radiation interaction, dust-direct effect, or dust-radiative effect) and 2) clouds (i.e., the dust–cloud interaction, dust-indirect effect, or dust-microphysical effect) ( Shi et al. 2014 , Fan et al. 2016 ). Generally, a layer of suspended dust heats the atmosphere within the layer and cools the
, southeast Pacific, west Pacific, and northeast Atlantic. In these regions, StCu cloud decks are not influenced by a seasonal biomass-burning layer such as the one in the southeast Atlantic. The Observations of Aerosols above Clouds and Their Interactions (ORACLES) campaign, taking place over the southeast Atlantic Ocean from 2016 to 2018, has provided new and unique observations for assessing cloud and aerosol interactions. Over the course of the first two years of the experiment, 18 different
, southeast Pacific, west Pacific, and northeast Atlantic. In these regions, StCu cloud decks are not influenced by a seasonal biomass-burning layer such as the one in the southeast Atlantic. The Observations of Aerosols above Clouds and Their Interactions (ORACLES) campaign, taking place over the southeast Atlantic Ocean from 2016 to 2018, has provided new and unique observations for assessing cloud and aerosol interactions. Over the course of the first two years of the experiment, 18 different
-emitted aerosols on climate have received more attention recently. The fire aerosols’ radiative effect (RE) and radiative forcing (RF) are estimated to quantify its impacts. RE represents the instantaneous radiative impact of atmospheric particles on Earth’s energy balance ( Heald et al. 2014 ), and RF is calculated as the change of RE between two different periods (e.g., preindustrial and present-day). The fire aerosols’ radiative effects/forcings could be due to aerosol–radiation interaction (ARI), aerosol–cloud
-emitted aerosols on climate have received more attention recently. The fire aerosols’ radiative effect (RE) and radiative forcing (RF) are estimated to quantify its impacts. RE represents the instantaneous radiative impact of atmospheric particles on Earth’s energy balance ( Heald et al. 2014 ), and RF is calculated as the change of RE between two different periods (e.g., preindustrial and present-day). The fire aerosols’ radiative effects/forcings could be due to aerosol–radiation interaction (ARI), aerosol–cloud
Review of Aerosol–Cloud Interactions: Mechanisms, Significance, and Challengesimpacts on cloud radiative forcing from the meteorological effects in observations and poor parameterizations of convection and clouds in numerical simulations especially for large-scale models cause the largest uncertainty in current estimates of climate forcing, which resides in aerosol–cloud interactions (ACI) that are traditionally referred to as aerosol indirect effects ( IPCC 2013 ). How aerosols affect cloud properties and precipitation through ACI strongly varies among cloud types that are
impacts on cloud radiative forcing from the meteorological effects in observations and poor parameterizations of convection and clouds in numerical simulations especially for large-scale models cause the largest uncertainty in current estimates of climate forcing, which resides in aerosol–cloud interactions (ACI) that are traditionally referred to as aerosol indirect effects ( IPCC 2013 ). How aerosols affect cloud properties and precipitation through ACI strongly varies among cloud types that are
). In summary, the local increases in Asian AA drive a cooling effect with negative changes in clear-sky SW radiation arising directly through the aerosol–radiation interaction. The cooling effect causes cooling trends in SAT and negative trends of hot extremes. Moreover, the trends in SAT in response to Asian AA increases exhibit spatial heterogeneity, with weak trends in SAT over NC, as a consequence of positive changes in SW CRE. The positive changes in SW CRE are due to the AA-induced atmosphere–cloud
). In summary, the local increases in Asian AA drive a cooling effect with negative changes in clear-sky SW radiation arising directly through the aerosol–radiation interaction. The cooling effect causes cooling trends in SAT and negative trends of hot extremes. Moreover, the trends in SAT in response to Asian AA increases exhibit spatial heterogeneity, with weak trends in SAT over NC, as a consequence of positive changes in SW CRE. The positive changes in SW CRE are due to the AA-induced atmosphere–cloud
aerosol–cloud interactions that tend to focus on microphysical responses to aerosol influences via traditional constructs ( Twomey 1977 ; Warner 1968 ) and instead attempts to incorporate a more boundary layer, cloud-system-centric view. While these aforementioned processes drive the responses that we aim to quantify, it is becoming increasingly clear that microphysical changes carry dynamical consequences. Stated differently, by changing cloud microphysical processes, the aerosol changes the
aerosol–cloud interactions that tend to focus on microphysical responses to aerosol influences via traditional constructs ( Twomey 1977 ; Warner 1968 ) and instead attempts to incorporate a more boundary layer, cloud-system-centric view. While these aforementioned processes drive the responses that we aim to quantify, it is becoming increasingly clear that microphysical changes carry dynamical consequences. Stated differently, by changing cloud microphysical processes, the aerosol changes the
different complexity of the aerosol model and aerosol activation parameterization, it underlines the importance of better understanding the two-way interaction between aerosols and clouds. The results may also to some extent explain why different cloud-resolving model studies have shown different results regarding aerosol-induced deep convective cloud sensitivity. It should be noted that the present study has been performed using a two-moment bulk microphysics scheme, which inherently includes certain
different complexity of the aerosol model and aerosol activation parameterization, it underlines the importance of better understanding the two-way interaction between aerosols and clouds. The results may also to some extent explain why different cloud-resolving model studies have shown different results regarding aerosol-induced deep convective cloud sensitivity. It should be noted that the present study has been performed using a two-moment bulk microphysics scheme, which inherently includes certain
