Substantial Cloud Brightening from Shipping in Subtropical Low Clouds

Diamond, Michael; Director, Hannah M.; Eastman, Ryan; Possner, Anna; Wood, Robert

doi:10.1002/essoar.10501145.1

Cited by 16 publications

(37 citation statements)

References 78 publications

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“…The average CRE was more negative within the shipping lane by ∼1% compared to the background clouds, similar to the comparison between the ship and no‐ship of Diamond et al. (2020). However, the net almost nil effect was composed of large negative CRE under a clean background ( N d‐bg < 50 cm −3 ), which was nearly fully countered by a positive forcing under polluted background ( N d‐bg > 70 cm −3 ).…”

Section: Discussionsupporting

confidence: 85%

“…As Figure 2b showed, the average value of N d‐core increases from west to the east with the proximity to land, except for the area affected by shipping, which constitutes a local maximum, in agreement with Diamond et al. (2020). Both areas A and C are considered as the background to which area B is compared.…”

Section: Methodssupporting

confidence: 90%

“…The shipping corridor was found to have elevated concentrations of SO 2 (Diamond et al., 2020). Therefore, SO 2 surface concentrations were used for identifying the shipping corridor in the study area.…”

Section: Methodsmentioning

confidence: 99%

“…However, ship emissions might impact clouds well beyond their initial effects on the visible linear features of the ship tracks (Goren & Rosenfeld, 2015). The quantification of ship emissions on all clouds was done recently by comparing the average cloud properties in a shipping lane to the adjacent less perturbed clouds (Diamond et al., 2020). They showed that an increase in N d is the lead cause of the small scene brightening (∼1%) in the shipping area in the southeast Atlantic Ocean.…”

Section: Introductionmentioning

confidence: 99%

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The Dependence of Ship‐Polluted Marine Cloud Properties and Radiative Forcing on Background Drop Concentrations

Zhu

Mao

et al. 2021

JGR Atmospheres

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Marine low clouds of the busy shipping lane in the southeast Atlantic during the springs of 2003–2015 were analyzed to study the dependence of their properties and radiative forcing on the background cloud drop concentrations (Nd‐bg). The overall average cloud radiative effect within the shipping lane was larger by only −1 Wm−2 compared to the adjacent clouds. However, this near‐zero averaged effect was composed of large negative cloud radiative forcing (CRF) for the cleanest (13%) of the cases with Nd‐bg < 50 cm−3, which was almost neutralized by a positive CRF for the 40% of the cases with Nd‐bg > 70 cm−3. A possible explanation for this positive forcing is the cloud burning effect of the black carbon from ship emissions. The negative forcing was composed of 45% for the cloud fraction (Cf) effect and 55% for the albedo effects, which included a small contribution of the liquid water path (LWP) effect. Positive Cf susceptibility to Nd‐core was at maximum for the lowest Nd‐bg and disappeared near 60 cm−3. The albedo susceptibility to Nd‐core reached its theoretical limit of 1/3 for constant LWP when Nd‐bg <40 cm−3, and diminishes to 0.2 when Nd‐bg = 60 cm−3. These susceptibilities represent cause and effect relationships because the differences of aerosols caused by the ship emissions vary at a much smaller scale than meteorology. Globally, under similar environmental conditions, nearly half of the area has Nd < 50 cm−3, thus possessing the indicated large susceptibility of negative radiative forcing to anthropogenic aerosols.

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Section: Discussionsupporting

confidence: 85%

Section: Methodssupporting

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Dependence of Ship‐Polluted Marine Cloud Properties and Radiative Forcing on Background Drop Concentrations

Zhu

Mao

et al. 2021

JGR Atmospheres

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“…The radiative forcing associated with aerosol‐cloud interactions, traditionally referred to as aerosol indirect effects, indirectly by modifying the microphysical properties of clouds, affecting their reflectivity and persistence, contributes the largest uncertainty to total radiative forcing estimates (Boucher et al., 2013). For liquid clouds, reducing droplet size and increasing reflectance of clouds due to increased droplet number for a constant liquid water path, namely the “Twomey” effect (Twomey, 1977), is relatively well understood (Christensen et al., 2020; Diamond et al., 2020; Liu & Li, 2019). However, aerosol effects on the amount of boundary layer clouds that cover large areas of the oceans and strongly reflect incoming solar radiation are still not well‐documented (Bellouin et al., 2020), especially the magnitude of the aerosol influence on cloud fraction (CF) (Ghan et al., 2016; Gryspeerdt et al., 2016).…”

Section: Introductionmentioning

confidence: 99%

Strong Aerosol Effects on Cloud Amount Based on Long‐Term Satellite Observations Over the East Coast of the United States

Yang

Wang

Zhu

et al. 2021

Geophysical Research Letters

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The radiative forcing associated with aerosol-cloud interactions, traditionally referred to as aerosol indirect effects, indirectly by modifying the microphysical properties of clouds, affecting their reflectivity and persistence, contributes the largest uncertainty to total radiative forcing estimates (Boucher et al., 2013). For liquid clouds, reducing droplet size and increasing reflectance of clouds due to increased droplet number for a constant liquid water path, namely the "Twomey" effect (Twomey, 1977), is relatively well understood (Christensen et al., 2020; Diamond et al., 2020; Liu & Li, 2019). However, aerosol effects on the amount of boundary layer clouds that cover large areas of the oceans and strongly reflect incoming solar radiation are still not well-documented (Bellouin et al., 2020), especially the magnitude of the aerosol influence on cloud fraction (CF) (Ghan et al., 2016; Gryspeerdt et al., 2016). Understanding how aerosols affect cloud cover helps to reduce the considerable uncertainty of the radiative forcing associated with aerosol-cloud interactions (Fan et al., 2016) because of the strong correlation of CF to other cloud properties and their large impact on radiation. The long-term satellite observations provide excellent opportunities for quantifying cloud-mediated aerosol radiative effects (

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Toward data assimilation of ship-induced aerosol–cloud interactions

Patel

Shand²

2022

Environ. Data Science

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Satellite imagery can detect temporary cloud trails or ship tracks formed from aerosols emitted from large ships traversing our oceans, a phenomenon that global climate models cannot directly reproduce. Ship tracks are observable examples of marine cloud brightening, a potential solar climate intervention that shows promise in helping combat climate change. In this paper, we demonstrate a simulation-based approach in learning the behavior of ship tracks based upon a novel stochastic emulation mechanism. Our method uses wind fields to determine the movement of aerosol–cloud tracks and uses a stochastic partial differential equation (SPDE) to model their persistence behavior. This SPDE incorporates both a drift and diffusion term which describes the movement of aerosol particles via wind and their diffusivity through the atmosphere, respectively. We first present our proposed approach with examples using simulated wind fields and ship paths. We then successfully demonstrate our tool by applying the approximate Bayesian computation method-sequential Monte Carlo for data assimilation.

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Substantial Cloud Brightening from Shipping in Subtropical Low Clouds

Cited by 16 publications

References 78 publications

The Dependence of Ship‐Polluted Marine Cloud Properties and Radiative Forcing on Background Drop Concentrations

The Dependence of Ship‐Polluted Marine Cloud Properties and Radiative Forcing on Background Drop Concentrations

Strong Aerosol Effects on Cloud Amount Based on Long‐Term Satellite Observations Over the East Coast of the United States

Toward data assimilation of ship-induced aerosol–cloud interactions

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