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Marine cloud brightening.

Latham J, Bower K, Choularton T, Coe H, Connolly P, Cooper G, Craft T, Foster J, Gadian A, Galbraith L, Iacovides H, Johnston D, Launder B, Leslie B, Meyer J, Neukermans A, Ormond B, Parkes B, Rasch P, Rush J, Salter S, Stevenson T, Wang H, Wang Q, Wood R - Philos Trans A Math Phys Eng Sci (2012)

Bottom Line: We describe herein an account of our recent research on a number of critical issues associated with MCB.We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result.There would also need to be an international agreement firmly in favour of such action.

View Article: PubMed Central - PubMed

Affiliation: National Centre for Atmospheric Research, Boulder, CO 80301, USA.

ABSTRACT
The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could-subject to satisfactory resolution of technical and scientific problems identified herein-have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seed-particle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud-albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100×100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action.

No MeSH data available.


Related in: MedlinePlus

Schematic of the proposed phase 2 and 3 field testing to evaluate the cloud responses to (a) a single-seeded plume; (b,c) multiple-seeded plumes. Examination of ship tracks from commercial ships [72] tells us that the plumes spread quasi-linearly with time at a rate of approximately 2 km h−1 [78], which for typical wind speeds of 5–10 m s−1 is a width of approximately 6–12 km at a distance of 100 km downwind of the source (a). For phase 3 testing, 5–10 ships (six shown in the example here) would be spaced approximately 10 km apart to generate a single plume 50–100 km wide at a distance of 100 km downwind (b). This broad plume and its surrounding unperturbed cloud would be sampled in the crosswind direction by stacked aircraft as discussed in the text (c). (Online version in colour.)
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RSTA20120086F13: Schematic of the proposed phase 2 and 3 field testing to evaluate the cloud responses to (a) a single-seeded plume; (b,c) multiple-seeded plumes. Examination of ship tracks from commercial ships [72] tells us that the plumes spread quasi-linearly with time at a rate of approximately 2 km h−1 [78], which for typical wind speeds of 5–10 m s−1 is a width of approximately 6–12 km at a distance of 100 km downwind of the source (a). For phase 3 testing, 5–10 ships (six shown in the example here) would be spaced approximately 10 km apart to generate a single plume 50–100 km wide at a distance of 100 km downwind (b). This broad plume and its surrounding unperturbed cloud would be sampled in the crosswind direction by stacked aircraft as discussed in the text (c). (Online version in colour.)

Mentions: Once the injection and dispersion technology has been tested and the aerosol plume characterized, the next stage is to examine the cloud responses to a single injection source. The cloud response to a single source will take the form of a ship track (albeit a deliberately produced one). Ship tracks are commonly observed features in regions of marine stratocumulus [72–75] and are associated with small particles emitted from large, commercial, diesel-burning ships [76]. There are existing field observations of ship tracks (e.g. the Monterey area ship track experiment in 1994; [77]). Figure 13 shows a schematic of the scale of such a plume. Ship tracks from commercial ships are typically 300 km in length and approximately 10 km wide a few hours downwind of the emitting ship [77].Figure 13.


Marine cloud brightening.

Latham J, Bower K, Choularton T, Coe H, Connolly P, Cooper G, Craft T, Foster J, Gadian A, Galbraith L, Iacovides H, Johnston D, Launder B, Leslie B, Meyer J, Neukermans A, Ormond B, Parkes B, Rasch P, Rush J, Salter S, Stevenson T, Wang H, Wang Q, Wood R - Philos Trans A Math Phys Eng Sci (2012)

Schematic of the proposed phase 2 and 3 field testing to evaluate the cloud responses to (a) a single-seeded plume; (b,c) multiple-seeded plumes. Examination of ship tracks from commercial ships [72] tells us that the plumes spread quasi-linearly with time at a rate of approximately 2 km h−1 [78], which for typical wind speeds of 5–10 m s−1 is a width of approximately 6–12 km at a distance of 100 km downwind of the source (a). For phase 3 testing, 5–10 ships (six shown in the example here) would be spaced approximately 10 km apart to generate a single plume 50–100 km wide at a distance of 100 km downwind (b). This broad plume and its surrounding unperturbed cloud would be sampled in the crosswind direction by stacked aircraft as discussed in the text (c). (Online version in colour.)
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3405666&req=5

RSTA20120086F13: Schematic of the proposed phase 2 and 3 field testing to evaluate the cloud responses to (a) a single-seeded plume; (b,c) multiple-seeded plumes. Examination of ship tracks from commercial ships [72] tells us that the plumes spread quasi-linearly with time at a rate of approximately 2 km h−1 [78], which for typical wind speeds of 5–10 m s−1 is a width of approximately 6–12 km at a distance of 100 km downwind of the source (a). For phase 3 testing, 5–10 ships (six shown in the example here) would be spaced approximately 10 km apart to generate a single plume 50–100 km wide at a distance of 100 km downwind (b). This broad plume and its surrounding unperturbed cloud would be sampled in the crosswind direction by stacked aircraft as discussed in the text (c). (Online version in colour.)
Mentions: Once the injection and dispersion technology has been tested and the aerosol plume characterized, the next stage is to examine the cloud responses to a single injection source. The cloud response to a single source will take the form of a ship track (albeit a deliberately produced one). Ship tracks are commonly observed features in regions of marine stratocumulus [72–75] and are associated with small particles emitted from large, commercial, diesel-burning ships [76]. There are existing field observations of ship tracks (e.g. the Monterey area ship track experiment in 1994; [77]). Figure 13 shows a schematic of the scale of such a plume. Ship tracks from commercial ships are typically 300 km in length and approximately 10 km wide a few hours downwind of the emitting ship [77].Figure 13.

Bottom Line: We describe herein an account of our recent research on a number of critical issues associated with MCB.We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result.There would also need to be an international agreement firmly in favour of such action.

View Article: PubMed Central - PubMed

Affiliation: National Centre for Atmospheric Research, Boulder, CO 80301, USA.

ABSTRACT
The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could-subject to satisfactory resolution of technical and scientific problems identified herein-have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seed-particle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud-albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100×100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action.

No MeSH data available.


Related in: MedlinePlus