Relationship between aerosol and cloud fraction over Australia

Griswold, Jennifer D. Small; Jiang, Jonathan H.; Su, Hui; Zhai, Chengxing

doi:10.1029/2011gl049404

Cited by 47 publications

(33 citation statements)

References 27 publications

(67 reference statements)

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“…Apparent AOD increases further in association with the clouds due to cloud contamination [ Koren et al, ] and thickening of the boundary layer near more‐developed convective clouds. This association of greater AOD in the vicinity of clouds might explain at least part of the reported increase in cloud cover with greater AOD and AI [ Sekiguchi et al, ; Kaufman et al, ; Kaufman and Koren , ; Loeb and Schuster , ; Koren et al, ; Dey et al, ; Small et al, ]. A physically based positive correlation exists between larger cloud fraction and deeper clouds, especially in convective cloud regimes.…”

Section: The Challenge Of Observing Cloud‐mediated Aerosol Radiative mentioning

confidence: 99%

Global observations of aerosol-cloud-precipitation-climate interactions

et al. 2014

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Cloud drop condensation nuclei (CCN) and ice nuclei (IN) particles determine to a large extent cloud microstructure and, consequently, cloud albedo and the dynamic response of clouds to aerosol-induced changes to precipitation. This can modify the reflected solar radiation and the thermal radiation emitted to space. Measurements of tropospheric CCN and IN over large areas have not been possible and can be only roughly approximated from satellite-sensor-based estimates of optical properties of aerosols. Our lack of ability to measure both CCN and cloud updrafts precludes disentangling the effects of meteorology from those of aerosols and represents the largest component in our uncertainty in anthropogenic climate forcing. Ways to improve the retrieval accuracy include multiangle and multipolarimetric passive measurements of the optical signal and multispectral lidar polarimetric measurements. Indirect methods include proxies of trace gases, as retrieved by hyperspectral sensors. Perhaps the most promising emerging direction is retrieving the CCN properties by simultaneously retrieving convective cloud drop number concentrations and updraft speeds, which amounts to using clouds as natural CCN chambers. These satellite observations have to be constrained by in situ observations of aerosol-cloud-precipitation-climate (ACPC) interactions, which in turn constrain a hierarchy of model simulations of ACPC. Since the essence of a general circulation model is an accurate quantification of the energy and mass fluxes in all forms between the surface, atmosphere and outer space, a route to progress is proposed here in the form of a series of box flux closure experiments in the various climate regimes. A roadmap is provided for quantifying the ACPC interactions and thereby reducing the uncertainty in anthropogenic climate forcing.

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Section: The Challenge Of Observing Cloud‐mediated Aerosol Radiative mentioning

confidence: 99%

Global observations of aerosol-cloud-precipitation-climate interactions

et al. 2014

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“…A strong link is also observed between τ and f c in both observations [ Sekiguchi et al , ; Kaufman et al , ; Kaufman and Koren , ; Loeb and Schuster , ; Koren et al , ; Dey et al , ; Koren et al , ; Small et al , ] and models [ Myhre et al , ; Quaas et al , ; Grandey et al , ]. These correlations have been found in several different cloud regimes, such as stratocumulus [ Costantino and Bréon , ] and convective anvils [ Koren et al , ], but they all show the same general form, a strong increase in f c with increasing τ .…”

Section: Introductionmentioning

confidence: 99%

Cloud fraction mediates the aerosol optical depth‐cloud top height relationship

Gryspeerdt

Stier

Grandey

2014

Geophysical Research Letters

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The observed strong link between aerosol optical depth (τ) and cloud top pressure (ptop) has frequently been interpreted as the invigoration of convective clouds by aerosol, with increased τ being strongly correlated with decreases in ptop (increases in cloud top height). A strong correlation between τ and cloud fraction (fc) has also been observed. Using satellite‐retrieved data, here we show that ptop is also strongly correlated to fc, and when combined with the strong sensitivity between fc and τ, a large proportion of the relationship between ptop and τcan be reconstructed. Given the uncertainties about the influence of aerosol‐cloud interactions on the τ‐fc relationship, this suggests that a large fraction of the τ‐ptop correlation may not be due to aerosol effects. Influences such as aerosol humidification and meteorology play an important role and should therefore be considered in studies of aerosol‐cloud interactions.

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“…4. Absorbing aerosol above cloud increases marine stratocumulus cloudiness [22,60,154]; absorbing aerosol in the boundary layer decreases cloudiness via reduction in surface fluxes over land and stabilization [1,34,70,71,132].…”

Section: Translating Insights From Process-scale Studies Into Constramentioning

confidence: 99%

The Radiative Forcing of Aerosol–Cloud Interactions in Liquid Clouds: Wrestling and Embracing Uncertainty

Mülmenstädt

Feingold

2018

Curr Clim Change Rep

111

101

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This article discusses some of the challenges that have limited progress in quantifying the radiative forcing associated with aerosol-cloud interactions (ACI) in warm (liquid-water) clouds. It reviews recent progress and suggests new ways of viewing the problem that might accelerate progress. It calls for much greater attention to the scale problem, both in terms of aerosol-cloud process representation in models and comparison with observations. It suggests careful consideration of the balance in detail with which processes are represented, and proposes a merging of detailed process understanding and system-wide behavior. In this spirit, it advocates tackling the problem with models of varying complexity that consider both the depth and breadth of the complex dynamical system. Finally, it considers shifting attention from untangling aerosol and meteorological effects on cloud systems towards understanding the co-variability of key aerosol and meteorological drivers of cloud systems.

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Relationship between aerosol and cloud fraction over Australia

Cited by 47 publications

References 27 publications

Global observations of aerosol-cloud-precipitation-climate interactions

Global observations of aerosol-cloud-precipitation-climate interactions

Cloud fraction mediates the aerosol optical depth‐cloud top height relationship

The Radiative Forcing of Aerosol–Cloud Interactions in Liquid Clouds: Wrestling and Embracing Uncertainty

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