A few thoughts:
1. This is not novel technology. Ice bridges, roads and islands have been built with both salt and freshwater. Thickened sea ice from ocean water has been used to make roads and both floating drilling platforms and platforms thick enough to anchor on the seabed in the shallow Beaufort Sea. For a sample reference, one of many, see http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCkQFjAA&url=http%3A%2F%2Fpubs.aina.ucalgary.ca%2Farctic%2FArctic33-1-168.pdf&ei=ehaoVJicAoKmNq2VhNgG&usg=AFQjCNH9gFxqWhBtkVOQIQ-c6lm23Q7daw&bvm=bv.82001339,d.eXY 2. Rapid formation of ice is enhanced by spraying a fine mist into the air (many who ski will have seen this done at ski hills). This is energy intensive, but could be used to accelerate the creation of sea ice in open water in the winter. 3. Simple low lift pumping of water onto the surface is the technique used in making ice bridges and road in the north. Very thick structures are made in weeks. 4. Andrew has expressed a concern about the formation of brine “lakes” on the top of ice if the concentrated brine does not find its way through the ice. (Brine is rejected into the ocean as natural sea ice forms at the bottom of an ice sheet, and sea ice tends to have many micro-channels.) Two thoughts. Any attempt to enhance the formation of sea ice would start with a small scale demonstration, and the brine question could be easily resolved. Second, what if brine does form on the surface? If the ice is going to melt anyway, one is left with sea water either way. 5. I think that adding anything to ice (like sawdust or straw) vastly complicates. First, it raises ecological questions, and second, as Andrew points out, the logistics are terrible. In this case I personally lean to “keep it simple”: just pump the water to surface to enhance heat transfer to the air during the cold winter. 6. Many years ago a graduate student and I did a conceptual evaluation of enhancing sea ice for a different purpose, to sustain the North Atlantic Deep Water (NADW) current that is the offset of the gulf stream. We envisioned that both spray and low lift pumping would be used on a massive scale to create one Sverdrup (10^6 m^3 per second) of downward current. The spray would hasten the formation of new sea ice, which would then be thickened by low lift pumping. The melting of this ice in the spring would enhance NADW, since a downflowing current in the North Atlantic requires both salinity and temperature. Hence we presumed that the surface ice created retained the brine/salt, but we noted that this was a key research question. Our work is in Zhou and Flynn, Climatic Change (2005) 71 203-220. I would be happy to forward a copy to anyone interested. 7. Either way, as Andrew notes, experimentation on a small demonstration scale would be helpful in resolving questions. I think it is important to note that such a demonstration would be using well proven past technologies that have been used in both salt and fresh water in order to answer questions specific to a sea ice enhancement project. Peter Flynn Peter Flynn, P. Eng., Ph. D. Emeritus Professor and Poole Chair in Management for Engineers Department of Mechanical Engineering University of Alberta [email protected] cell: 928 451 4455 *From:* [email protected] [mailto: [email protected]] *On Behalf Of *Andrew Lockley *Sent:* January-03-15 3:42 AM *To:* John Nissen; geoengineering *Subject:* Re: [geo] Watch "Integrated Assessment of Geoengineering Proposals…" on YouTube It's not so simple.... 1 the Arctic is basically a small continent, so scales are enormous 2 adding straw, etc is a great idea, but logistics are horrific 3 brine rejection is a big issue. It needs to either drain through the ice (needing drilling or pumping) or it will pond on the surface or as inclusions (probably both) the resulting ice is unnatural and unstable, as it's darker and more prone to fracture. 4 it may be far easier to use icebreakers, which expose a lot of clear, dark water. They also don't have a brine rejection issue. 5 thickening key areas of ice may be far more effective than general thickening, as most ice loss is ultimately wind driven. You need only stop the wind clearance, and you stop the loss (to a point) Experiments are needed before advocacy. A On 3 Jan 2015 10:35, "John Nissen" <[email protected]> wrote: Hi Peter, Thanks for this important contribution to the discussion on cooling the Arctic. We need to throw as many practical techniques as we can at this problem, since saving the sea ice is so vital. And speed is vital - so we should start pumping this winter! But there are some questions about the method. Does one need to use fresh water, or will sea water suffice? Should one spray the water to produce snow for wider cover, or can one simply pour the water onto the ice? Is there a pattern one should produce, e.g. ridges to form a hexagonal lattice? Could one mix the water with straw, sawdust or other organic material to produce stronger ice (called "pykrete") and make the structure even stronger and more resistant to melting and break-up in the spring. Where should one most concentrate ones efforts - should it be at the anticipated edge of the ice where break-up would be most telling in summer? May I invite others to join in this debate? We need rapid resolution of these and other questions if we are to make a convincing proposal for action in the face of rapidly disappearing sea ice. Time is running out. Cheers, John On Sat, Jan 3, 2015 at 12:48 AM, Peter Flynn <[email protected]> wrote: Cooling the Arctic will drop the temperature and get to the fundamental cause of shrinking ice: rising temperature. In the meantime, the formation of ice can be vastly accelerated by a simple and well demonstrated technology: pump water on top of ice during the winter. The fundamental concept is that there is plenty of “cold” in the winter, one simply gets around the insulating impact of the ice itself (in nature, incremental sea ice forms at the bottom of the sheet). Spray technologies, energy intensive, have built ice islands for drilling platforms in one season that are 8 meters plus in thickness; this is much like making “snow” on ski hills. Ice bridges are typically built with low energy intensity: just pump water on top of existing ice. One merit of this approach is that it can be instantly stopped if any unanticipated negative impact arises, reducing the fear factor in the uninformed. Making sea ice doesn’t address the rising temperature itself other than by restoring the albedo of the ice cover itself, but it does sustain the ice. I think it is a good companion to temperature/insolation modification schemes. Peter Flynn Peter Flynn, P. Eng., Ph. D. Emeritus Professor and Poole Chair in Management for Engineers Department of Mechanical Engineering University of Alberta [email protected] cell: 928 451 4455 *From:* [email protected] [mailto: [email protected]] *On Behalf Of *John Nissen *Sent:* January-02-15 8:50 AM *To:* [email protected] *Cc:* Alan Gadian; Stephen Salter; geoengineering *Subject:* Re: [geo] Watch "Integrated Assessment of Geoengineering Proposals…" on YouTube Dear Rob, This is an extremely relevant discussion for any attempt to cool the Arctic in order to halt sea ice retreat. (There is strong evidence that the retreat is already having an effect on N Hemisphere climate due to jet stream disruption, so a strong argument to try cooling the Arctic ASAP.) The two main approaches being considered are (i) to produce a reflecting stratospheric haze at mid to high latitude and (ii) to brighten marine clouds (MCB) in the troposphere over the North Atlantic and North Pacific. In both cases the aim is to cool surface water flowing into the Arctic and thereby slow sea ice melt and allow it to reform more easily. Much of the surface water at higher latitudes (between about 50N and 70N) finds its way into the Arctic. About 10% of the world's freshwater flows in the Arctic Ocean. Most of your discussion has involved consideration of MCB, creating the cloud condensation nuclei (CCN) from ships. Since there are so many unknowns about the effectiveness, couldn't we have some useful experiments from aircraft, or has this been done already? For example, you point out that turbulence changes could reduce or enhance the initial enhancement - and if it is a reduction this could be showstopper. Two further approaches for cooling the Arctic involve clouds: (iii) cloud removal to increase outgoing thermal radiation, and (iv) cloud seeding to produce fresh snow and thereby increase surface albedo on a regional scale. In both these cases, we need to test the production of CCN from aircraft and monitor effectiveness. Could you envisage a crash programme for testing of these various approaches, to see which is most appropriate and effective in different locations, at different times of year and under different circumstances (existing cloud conditions, etc)? Has anything like this been done already? Cheers, John On Thu, Jan 1, 2015 at 4:47 PM, Rob Wood <[email protected]> wrote: A straightforward way to prevent plume sinking (if indeed it turns out to be undesirable for particle dispersion), is to heat the stack. This happens already on all cargo ships. I don't believe that coagulation will be a showstopper although experiments will be necessary to confirm this because coagulation depends on the exact size distribution and charging and this cannot be predicted from modeling alone. Some degree of charging may well occur (not my expertise) but this will likely depend on the spray method. Effervescent spray atomization (see Cooper et al. article in Phil Trans 2014 special issue), does not seem to make a lot of charged particles. Observations show that shiptracks are rarely observed in boundary layers deeper than 1km. Globally, most stratocumulus occurs in PBLs deeper than this. But shiptracks themselves (although highly visible) are not necessary for MCB to work. Greater dispersion in the subcloud layer prior to ascent into the stratocumulus deck in the intermittently coupled layer above, might increase efficacy by producing a more evenly distributed droplet concentration enhancement (Stephen alluded to this). That said, I disagree that the albedo enhancement required (e.g., to offset CO2 doubling globally, i.e., about 4 W/m2) is small. Only 20% of the planet has clouds that may be seedable, so the solar reflection of seeded clouds would need to be enhanced by >20 W/m2 (this number being generous because it is highly unlikely that uniform seeding is possible). This is about one fifth to one quarter of typical cloud albedo. More important than whether the human eye can detect the brightening, is that spatial albedo enhancement gradients, and changes to the condensate amounts due to e.g. drizzle suppression, will drive turbulence changes and also regional scale circulation changes that produce cloud adjustments that could reduce or enhance the initial enhancement. For example, it is known that on average, condensate amounts in shiptracks are lower than in surrounding clouds (e.g. Coakley and Walsh 2002, Chen et al. 2014) because reduced precipitation in the track leads to stronger turbulence which drives greater entrainment of dry free tropospheric air that thins the cloud layer. Ackerman et al. (2004, Nature) first noticed this in large eddy models, and I wrote a paper that attempted to explain this behavior with a simple model (Wood, J. Atmos. Sci. 2007). These responses are difficult to capture in climate models as they depend upon subgrid scale processes that are poorly represented in models with re solutions greater than a few hundred meters horizontal and a few meters in the vertical. A big challenge. This *might* be the biggest showstopper of all for MCB. Regards Rob On 1/1/2015 4:36 AM, Alan Gadian wrote: Stephen, I am afraid I cannot comment on the electrification, but I would like to emphasise the dynamics again. WRF (and WRF Chem ) can be driven either by an observed real data, or in an idealised WRF - LEM form ( with no BL parameterisation scheme) driven from an atmospheric profile In all LEM modelling of Sc, an important feature is always entrainment and mixing. The horizontal and vertical velocities and the "rolls" or "eddies" are critical in this. If there is a decoupled layer near the surface, for example, as is sometimes / often observed then this will critically affect the dispersion. I am still uncertain what was run in the WRF chem simulation, what BL scheme was used in the IGAP runs, but the argument I am proposing was that the velocity structure is unlikely to be correct, unless actually verified with observations. I am trying the think of examples. Yamaguchi & Feingold , 2014, show the changes in turbulence patterns, Wang and Fiengold (2009) and other work including that of Wood ( not mentioned as he is part of this discussion) show examples of this importance of the turbulence and eddies. I know that volcanoes are completely different, and this work is not at the required resolution for SC clouds, but the attached poster, probably without video, is some work that we did. We had to run WRF in LEM mode to get anywhere near the correct eddy structures for the near volcanic plume eddies. Again looking at the high resolution modelling work of AndrejczuK (some of which Rob was again involved with), the role of the interaction between the dynamical eddy structure and the microphysics and latent heat exchange is crucial. Thus again, I feel that there are a lot of uncertainties in the modelling work, and the only way to see if MCB works is to do an experiment Alan Gadian On Thu, 1 Jan 2015, Stephen Salter wrote: Hi All The words 'charge' and 'electrostatic' do not appear in Stuart et 2013. People cleaning oil tanks in the 1960's found the painful way that its is difficult NOT to generate charge, see http://www.infostatic.co.uk/Papers/TankWashingRisks.pdf . There are at least two ways by which we can control charge. The Stuart paper used a size distribution of 100 size bins, spaced logarithmically between 10 nm and 10 μm in wet diameter rather than mono-disperse spray. This is a range of 1000:1. I hope to keep within 20%. Coagulation requires a relative velocity between drops. Viscous forces are very large at sub-micron dimension. Particles will behave like sand in honey. Small scale turbulence will tend to vary the velocity of particles but while the Stokes drag force goes with the first power of diameter the mass resisting acceleration goes with the cube. If there is a wide range of drop diameters, local turbulence will produce much larger range of relative velocities. It would be useful to know coagulation rates for narrow ranges of drop diameter. In my paper on the detection of small contrast changes I assumed a loss of 50% which would not be a show stopper. In figure 2 of of the Stuart paper there is no sign of any initial drop due to evaporative cooling. Stephen Emeritus Professor of Engineering Design. School of Engineering. University of Edinburgh. Mayfield Road. Edinburgh EH9 3JL. Scotland [email protected] Tel +44 (0)131 650 5704 Cell 07795 203 195 WWW.see.ed.ac.uk/~shs YouTube Jamie Taylor Power for Change On 01/01/2015 02:48, Alan Gadian wrote: Rob, I agree here with you. With LEM modelling with WRF Chem, the bdy layer schemes can be very diffusive. Ignoring the electrostatics charge element, I am concerned that the PDFs of the vertical velocities are critical. From experience 20m is not good enough resolution in the vertical. How does the model cope with changes in cloud droplet number, as seen in andrejczuk (2012 aNd 2014) . The vocals profiles provide data on the BL dynamical profiles, and I fear with the wef chem LEM results, the dynamics and hence the dispersion are inadequately represented. WRF Chem is about 20 times slower than WRF without the chemistry package, and thus the representation of the dynamics has to be compromised for the inclusion of the chemistry. I would like it clarified about how these results compare with observations. The papers of Andrejcuck provide a surprisingly efficient and rapid dispersion, and compare reasonably well with observations. Alan T --- Alan Gadian, NCAS, UK, ( sent from a mobile device ) Email: [email protected] or [email protected] Tel: +44 / 0 775 451 9009 or +44 / 0 113 343 7246 T --- On 31 Dec 2014, at 23:46, Rob Wood <[email protected]> <[email protected]> wrote: Dear All, I think that some degree of coagulation given such localized point sources of large numbers of particles is inevitable, as shown in the paper by Stuart et al. (2013). This will also be the case with charged particles. Nevertheless, I don't think that this is necessarily a fundamental limitation. After all, shiptrack formation, where even larger numbers of particles are produced, still occurs. Coagulation must be considered in the calculations. That said, in our recent paper (Connolly et al. 2014), we found significant albedo enhancement in a parcel model even with quite broad size distributions. The optimal median particle size becomes smaller as the size distribution spread broadens (e.g. from coagulation). For broader distributions typical of those produced in lab tests, the optimal median droplet diameters need to be somewhat smaller than 0.1 micron. I tend to agree with Stephen that near-surface spreading due to initial negative buoyancy from evaporation of water from the small seawater droplets may not necessarily be a tremendous problem for the reasons he states. This has not yet been considered in any model that I know of, but could easily be done with large eddy models. Rob Wood On 12/30/2014 8:35 AM, Stephen Salter wrote: Hi All Piers Forster's concern in his video about spray coagulation would be reduced if his model had used mono-disperse drops with an electrostatic charge as specified in our 2008 paper on sea-going hardware. His concern about detecting the effectiveness is because the cloud contrast change needed to save humanity is below the detection threshold of the human eye. However contrast can be enhanced by the superposition of satellite aligned images. I have previously circulated some to this group and hope that the idea will give quantitative results in a few days. The picture of spray plumes shown in box 3 of his IAGP practicalities note must have been using warm air from a chimney. Depending on the temperature and relative humidity of the surrounding ambient air there will be several degrees of temperature drop due to the latent heat of evaporation. The increase of density will lead to a rapid fall of the cooled air which will spread out over the sea surface like a spilt liquid until it has been warmed by the large area of contact with sea. You can show this fall and dispersion very cheaply with a pond fogger, £19.99 from Maplin. We want this dispersion because a low dose over a large area is more effective than a high point dose. Forster seems to be ignoring completely the idea of coded modulation of CCN concentration in climate models even though the satisfactory operation was demonstrated by Ben Parkes doing a PhD in Forster's own Department at Leeds in 2012. This might allow us to get an everywhere-to-everywhere transfer function of marine cloud brightening and win-win result with more rain in dry places and less in wet. The high frequency response means that we can give a tactical spraying based local day-to-day observations. It is a puzzle that the Parkes thesis has, yet again, vanished from the Leeds University website. Stephen Emeritus Professor of Engineering Design. School of Engineering. University of Edinburgh. Mayfield Road. Edinburgh EH9 3JL. Scotland [email protected] Tel +44 (0)131 650 5704 Cell 07795 203 195 WWW.see.ed.ac.uk/~shs YouTube Jamie Taylor Power for Change On 28/12/2014 20:03, Andrew Lockley wrote: Integrated Assessment of Geoengineering Proposals…: http://youtu.be/FFjzzfCLCqw Poster's note : I personally have found it very difficult to access and appraise the science behind the IAGP project. Despite this, a vast amount of publicity has been obtained for the project. I think the IAGP team could do more to encourage early, in-depth access to their material, particularly bearing in mind the huge media interest. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. 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