Dear Josh,
If the concentration of background particle were large enough, a few
hundred particle per cm3, then this would inhibit new particle
production. At least this is case in the marine boundary layer. I
understand that stratospheric microphysical models are having trouble
making new particles. However, adding NH3 would allow ternary
nucleation tens of thousands of times faster than sulfuric acid and
water alone as is seen in the free troposphere.
In terms of a volcanic eruptions like Pinatubo, I wonder how much ash
made it to the stratosphere and provided nucleation sites?
Sincerely,
Oliver Wingenter
On 10/17/2010 12:29 PM, Ken Caldeira wrote:
Multiple, independent injections would /decrease /the likelihood of
coagulation relative to injecting it all in one place.
Of course, there is potential for coordinated injections to decrease
coagulation (aggregation) relative to uncoordinated injections.
There is no evidence that I know of that one injection could "cancel
out" the effects of another injection. It seems that the main case is
that the climate effect of A+B would be less than the climate effects
of A plus the climate effects of B.
It is an interesting research question to understand whether there are
countermeasures that would decrease the effectiveness of injection by
injecting something upwind from an injection site that would promote
aggregation of the injected material.
___________________________________________________
Ken Caldeira
Carnegie Institution Dept of Global Ecology
260 Panama Street, Stanford, CA 94305 USA
+1 650 704 7212 [email protected]
<mailto:[email protected]>
http://dge.stanford.edu/labs/caldeiralab @kencaldeira
On Sun, Oct 17, 2010 at 10:43 AM, Josh Horton
<[email protected] <mailto:[email protected]>> wrote:
Hi everyone,
I am finalizing a chapter on geoengineering policy for publication and
would greatly appreciate informed feedback on the following paragraph:
"The aerosol most commonly suggested for stratospheric injection is
sulfuric acid. Plans call for delivering sulfate aerosols by
dispersing gas-phase precursor materials. Precursor oxidation and
aerosol formation involve complex processes with the potential to
reduce the effectiveness of stratospheric insertion. For instance,
coagulation could lead to excessively large sulfuric acid particles
that sediment out of the stratosphere, neutralizing the effect of the
initial dispersion. Multiple, independent injections would increase
the likelihood of such unintended consequences. Unsynchronized
staging, scheduling, and delivery of sulfate aerosol injections would
magnify the potential for perverse particulate interactions, and might
jeopardize the success of geoengineering deployment. Lack of policy
coordination may result in separate injection schemes that effectively
cancel each other out."
For those with scientific/technical backgrounds, is this a sound
argument? Is the basic science correct? I am outside my comfort zone
with this and want to be sure I don't miss the mark. Thanks to anyone
who can offer insight.
Josh Horton
[email protected] <mailto:[email protected]>
http://geoengineeringpolitics.blogspot.com/
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