Interpreting the cloud cover – aerosol optical depth relationship found in satellite data using a general circulation model

Quaas, Johannes; Stevens, Björn; Stier, Philip; Lohmann, Ulrike

doi:10.5194/acp-10-6129-2010

Cited by 184 publications

(168 citation statements)

References 51 publications

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“…Previous modelling studies suggest that the majority of the AOD-CF correlation can be explained by aerosol humidification increasing the AOD in regions of high relative humidity (Quaas et al, 2010). Similar results have been shown using satellite data (Engstrom and Ekman, 2010).…”

Section: Introductionsupporting

confidence: 77%

“…It is not used when determining the frequency of occurrence of the regimes, only when investigating the frequency of the transitions between the regimes. While this process removes any effects of aerosol on CF, previous studies have shown that this represents a small fraction of the overall AI-CF correlation (Quaas et al, 2010). The main result of this process is to remove non-aerosol effects linking CF and AI.…”

Section: Meteorological Effectsmentioning

confidence: 99%

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Satellite observations of cloud regime development: the role of aerosol processes

2014

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Abstract. Many different interactions between aerosols and clouds have been postulated, based on correlations between satellite retrieved aerosol and cloud properties. Previous studies highlighted the importance of meteorological covariations to the observed correlations.In this work, we make use of multiple temporally-spaced satellite retrievals to observe the development of cloud regimes. The observation of cloud regime development allows us to account for the influences of cloud fraction (CF) and meteorological factors on the aerosol retrieval. By accounting for the aerosol index (AI)-CF relationship, we reduce the influence of meteorological correlations compared to "snapshot" studies, finding that simple correlations overestimate any aerosol effect on CF by at least a factor of two.We find an increased occurrence of transitions into the stratocumulus regime over ocean with increases in MODIS AI, consistent with the hypothesis that aerosols increase stratocumulus persistence. We also observe an increase in transitions into the deep convective regime over land, consistent with the aerosol invigoration hypothesis. We find changes in the transitions from the shallow cumulus regime in different aerosol environments. The strength of these changes is strongly dependent on Low Troposphere Static Stability and 10 m windspeed, but less so on other meteorological factors.Whilst we have reduced the error due to meteorological and CF effects on the aerosol retrieval, meteorological covariation with the cloud and aerosol properties is harder to remove, so these results likely represent an upper bound on the effect of aerosols on cloud development and CF.

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Section: Introductionsupporting

confidence: 77%

Section: Meteorological Effectsmentioning

confidence: 99%

Satellite observations of cloud regime development: the role of aerosol processes

2014

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“…In clear conditions with low humidity, the SNR is low due to a weak backscattering. When the humidity increases, the aerosols swell and the backscattering is increased [21]. With the optimal SNR limit of −10 dB, the availability is reduced to 74.2% due to a loss of such periods.…”

Section: Validation Of Lidar Measurementsmentioning

confidence: 99%

Wind in Complex Terrain—Lidar Measurements for Evaluation of CFD Simulations

et al. 2018

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Abstract:Computational Fluid Dynamics (CFD) is widely used to predict wind conditions for wind energy production purposes. However, as wind power development expands into areas of even more complex terrain and challenging flow conditions, more research is needed to investigate the ability of such models to describe turbulent flow features. In this study, the performance of a hybrid Reynolds-Averaged Navier-Stokes (RANS)/Large Eddy Simulation (LES) model in highly complex terrain has been investigated. The model was compared with measurements from a long range pulsed Lidar, which first were validated with sonic anemometer data. The accuracy of the Lidar was considered to be sufficient for validation of flow model turbulence estimates. By reducing the range gate length of the Lidar a slight additional improvement in accuracy was obtained, but the availability of measurements was reduced due to the increased noise floor in the returned signal. The DES model was able to capture the variations of velocity and turbulence along the line-of-sight of the Lidar beam but overestimated the turbulence level in regions of complex flow.

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“…Meanwhile, positive correlation between TCC and AOD derived from satellite data has been found in the previous studies (Loeb et al, 2005). Quaas et al (2010) proposed six main hypotheses to interpret the relationship between AOD and TCC. Among these wet scavenging is the only one showing negative correlation.…”

Section: Relation Between Cloud and Aerosolmentioning

confidence: 99%

Inter-Annual Variations of Cloud and Precipitation and their Possible Relationships with Surface Aerosols in Shanghai

Zhang

Duan

et al. 2015

Aerosol Air Qual. Res.

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Aerosol-cloud-precipitation interactions have attracted much more attention for decades, but there still remain many uncertainties in assessing global climate. Long-term ground-based measurements of aerosol, cloud and precipitation in Shanghai were used to examine their inter-annual variations and possible relationships. During 1990-2010, the yearlyaveraged total cloud cover (TCC) and low cloud cover (LCC) decrease on average by 0.58% and 2.49% per year. LCC correlates to surface aerosols (e.g., PM 10 ), with a correlation coefficient (R) of 0.67. Aerosol optical depth (AOD), as an indicator of columnar aerosol loading, shows a non-significant correlation with cloud cover. The yearly-aggregated heavy and extreme rain days and their rainfall amount increase gradually. The moderate rain day enhances but its annual rainfall amount declines year by year, while the light rain exhibits an opposite pattern to the moderate rain. These results imply that local aerosols maybe exert somewhat enforcing on low cloud and light rain through possible entrainment or updraft that can bring up surface particles into free troposphere, whereas its influence to total cloud and precipitation is negligible at a small scale. Future studies are needed to ensure whether local aerosols to directly affect low cloud, and to explore how surface aerosols to enter into higher atmospheric layers and impact cloud and precipitation at larger scales.

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Interpreting the cloud cover – aerosol optical depth relationship found in satellite data using a general circulation model

Cited by 184 publications

References 51 publications

Satellite observations of cloud regime development: the role of aerosol processes

Satellite observations of cloud regime development: the role of aerosol processes

Wind in Complex Terrain—Lidar Measurements for Evaluation of CFD Simulations

Inter-Annual Variations of Cloud and Precipitation and their Possible Relationships with Surface Aerosols in Shanghai

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