Ian
Stephen Salter
Hi All
Some of you may not have seen the attached. Apologies to those who have.
If you would like other input assumptions please let me know. The annual benefit-to-cost ratio would survive quite large changes
If you cannot see any mistakes please pass it on.
Stephen
Emeritus Professor of Engineering Design
School of Engineering
University of Edinburgh
Mayfield Road
Edinburgh EH9 3DW
Scotland
0131 650 5704 or 662 1180
Andrew Lockley
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Stephen Salter
Andrew
And here is the counter counterpoint.
The futility authors have not replied to the 5000 to 1 ratio.
Stephen
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Subject: Re: [geo] Ian
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Stephen Salter
Andrew
Sorry I jumped the gun.
Your article in Nature of 19 August https://www.nature.com/articles/s43247-022-00519-1 says that attempts to weaken tropical cyclones by ocean cooling would be futile.
I attach a note about the use of autonomous, wind-driven spray vessels to do this and would be grateful if you could check my calculations. The vessel design follows the proposal by Latham to exploit the Twomey effect to increase global reflectivity.
If you want to act when a hurricane is forecast you will be too late. You should have started last November. I would want vessels to cruise between Africa and the Gulf of Mexico, an area 50 times more than your figure. I want to do this over 200 days, 100 times longer than you suggest. We therefore disagree by a factor of 5000!
I want to adjust vessel position and spray rate using satellite temperature measurements to get the pattern of sea surface temperatures to approach those given by the Governments of surrounding countries. They will adjust payments to spraying contractors according to how close they can get.
I attach calculations on the vessel number required. The answer depends on a number of assumptions for solar input, cloud fraction, boundary layer depth, initial nuclei concentration and subsequent life of spray. These vary widely. The ones I have used have been circulated for comment to the climate community and I can easily change them to ones you suggest. If you accept them, the number of vessels for moderating Atlantic hurricanes by a 2K reduction in sea surface temperature is about 300.
Vessel design is nearly complete. The displacement is 90 tonnes and the power requirement 300 kW. Flower class Corvettes were built in similar numbers but with higher power and displacement. If we index link Corvette cost and use the present cost per tonne of heavy earth moving machinery we can hope that vessel cost in full production will be about $5million each.
I would be grateful if you could check my figures and suggest desirable temperature patterns. Is cooling of 2K enough?
Would you like to see calculations about sea level rise and Arctic ice and a way to increase sea evaporation?
Stephen