Satellite observations of ship emission induced transitions from broken to closed cell marine stratocumulus over large areas

Goren, Tom

doi:10.1029/2012jd017981

Cited by 61 publications

(80 citation statements)

References 90 publications

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“…L. McCoy et al, 2017). Numerous studies have linked the dominance of open or closed mesoscale cellular convection to precipitation and aerosol modulation of precipitation (Stevens et al, 2005;Feingold et al, 2015;Koren and Feingold, 2011;Rosenfeld et al, 2006;Mechem et al, 2012;Goren and Rosenfeld, 2012;Wang and Feingold, 2009a, b). Because of the tenuous nature of this cloud regime, and because they are typically precipitating, it is reasonable to suspect that they will be more susceptible to aerosol-driven changes in their macrophysics than either thick frontal clouds or non-precipitating clouds.…”

Section: Differences In the Structure Of Clouds Within Cyclones As A mentioning

confidence: 99%

Aerosol midlatitude cyclone indirect effects in observations and high-resolution simulations

et al. 2018

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Abstract. Aerosol-cloud interactions are a major source of uncertainty in inferring the climate sensitivity from the observational record of temperature. The adjustment of clouds to aerosol is a poorly constrained aspect of these aerosolcloud interactions. Here, we examine the response of midlatitude cyclone cloud properties to a change in cloud droplet number concentration (CDNC). Idealized experiments in high-resolution, convection-permitting global aquaplanet simulations with constant CDNC are compared to 13 years of remote-sensing observations. Observations and idealized aquaplanet simulations agree that increased warm conveyor belt (WCB) moisture flux into cyclones is consistent with higher cyclone liquid water path (CLWP). When CDNC is increased a larger LWP is needed to give the same rain rate. The LWP adjusts to allow the rain rate to be equal to the moisture flux into the cyclone along the WCB. This results in an increased CLWP for higher CDNC at a fixed WCB moisture flux in both observations and simulations. If observed cyclones in the top and bottom tercile of CDNC are contrasted it is found that they have not only higher CLWP but also cloud cover and albedo. The difference in cyclone albedo between the cyclones in the top and bottom third of CDNC is observed by CERES to be between 0.018 and 0.032, which is consistent with a 4.6-8.3 Wm −2 in-cyclone enhancement in upwelling shortwave when scaled by annualmean insolation. Based on a regression model to observed cyclone properties, roughly 60 % of the observed variability in CLWP can be explained by CDNC and WCB moisture flux.

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Section: Differences In the Structure Of Clouds Within Cyclones As A mentioning

confidence: 99%

Aerosol midlatitude cyclone indirect effects in observations and high-resolution simulations

et al. 2018

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“…While CCN injections were found to induce transitions from open-to closed-cell stratocumulus by suppressing drizzle formation Goren and Rosenfeld, …”

Section: Introductionmentioning

confidence: 99%

“…In particular it has been shown in both satellite observations (Christensen and Stephens, 2011;Chen et al, 2012;Goren and Rosenfeld, 2012) and modelling studies Kazil et al, 2011;Berner et al, 2013) that changes in the background aerosol and cloud condensation nuclei (CCN) concentrations not only affect the cloud albedo by producing more numerous and smaller cloud droplets (Twomey effect, 1974), but may also induce transitions between cloud regimes, which fundamentally change the boundary layer state.…”

Section: Introductionmentioning

confidence: 99%

Real-case simulations of aerosol–cloud interactions in ship tracks over the Bay of Biscay

et al. 2015

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Abstract. Ship tracks provide an ideal test bed for studying aerosol-cloud interactions (ACIs) and for evaluating their representation in model parameterisations. Regional modelling can be of particular use for this task, as this approach provides sufficient resolution to resolve the structure of the produced track including their meteorological environment whilst relying on the same formulations of parameterisations as many general circulation models. In this work we simulate a particular case of ship tracks embedded in an optically thin stratus cloud sheet which was observed by a polar orbiting satellite at 12:00 UTC on 26 January 2003 around the Bay of Biscay.The simulations, which include moving ship emissions, show that the model is indeed able to capture the structure of the track at a horizontal grid spacing of 2 km and to qualitatively capture the observed cloud response in all simulations performed. At least a doubling of the cloud optical thickness was simulated in all simulations together with an increase in cloud droplet number concentration by about 40 cm −3 (300 %) and decrease in effective radius by about 5 µm (40 %). Furthermore, the ship emissions lead to an increase in liquid water path in at least 25 % of the track regions.We are confident in the model's ability to capture key processes of ship track formation. However, it was found that realistic ship emissions lead to unrealistic aerosol perturbations near the source regions within the simulated tracks due to grid-scale dilution and homogeneity.Combining the regional-modelling approach with comprehensive field studies could likely improve our understanding of the sensitivities and biases in ACI parameterisations, and could therefore help to constrain global ACI estimates, which strongly rely on these parameterisations.

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“…Conover, 1966;Coakley et al, 1987;Durkee et al, 2000b;Christensen and Stephens, 2011;Peters et al, 2011;Chen et al, 2012;Goren and Rosenfeld, 2012) and modelling (e.g. Capaldo et al, 1999;Lauer et al, 2007;Wang and Feingold, 2009;Righi et al, 2011;Lund et al, 2012;Peters et al, , 2013Partanen et al, 2013) approaches.…”

Section: Introductionmentioning

confidence: 99%

Processes limiting the emergence of detectable aerosol indirect effects on tropical warm clouds in global aerosol-climate model and satellite data

Peters

Quaas

Stier

et al. 2014

Tellus B: Chemical and Physical Meteorology

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A B S T R A C TWe use data from simulations performed with the global aerosol-climate model ECHAM5-HAM to test the proposition that shipping emissions do not have a statistically significant effect on water clouds over tropical oceans on climate scales put forward in earlier satellite based work. We analyse a total of four sensitivity experiments, three of which employ global shipping emissions and one simulation which only employs shipping emissions in the mid-Atlantic Ocean. To ensure comparability to earlier results from observations, we sample the model data using a method previously applied to satellite data aimed at separating 'clean' from 'polluted' oceanic regions based on i) the location of main shipping routes and ii) wind direction at 10 m above sea level. The model simulations run with realistic present-day shipping emissions show changes in the lower tropospheric aerosol population attributable to shipping emissions across major shipping corridors over tropical oceans. However, we find the resulting effect on cloud properties to be non-distinguishable from natural gradients and variability, that is, gradients of cloud properties sampled across major shipping corridors over tropical oceans are very similar among those simulations. Our results therefore compare well to the earlier findings from satellite observations. Substantial changes of the aerosol population and cloud properties only occur when shipping emissions are increased 10-fold. We find that aerosol advection and rapid aerosol removal from the atmosphere play an important role in determining the non-significant response in i) column integrated aerosol properties and ii) cloud microphysical properties in the realistic simulations. Additionally, high variability and infrequent occurrence of simulated low-level clouds over tropical oceans in ECHAM5-HAM limit the development of aerosol indirect effects because i) in-cloud production of sulphate from ship-emitted sulphuric species via aqueous oxidation pathways is very low and ii) a possible observational signal is blurred out by high variability in simulated clouds. Our results highlight i) the importance of adequately accounting for atmospheric background conditions when determining climate forcings from observations and ii) the effectiveness of buffering mechanisms on micro-and macroscopic scales which limit the emergence of such climate forcings.

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Satellite observations of ship emission induced transitions from broken to closed cell marine stratocumulus over large areas

Cited by 61 publications

References 90 publications

Aerosol midlatitude cyclone indirect effects in observations and high-resolution simulations

Aerosol midlatitude cyclone indirect effects in observations and high-resolution simulations

Real-case simulations of aerosol–cloud interactions in ship tracks over the Bay of Biscay

Processes limiting the emergence of detectable aerosol indirect effects on tropical warm clouds in global aerosol-climate model and satellite data

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