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complément du document aurora par david keith.pdf


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Supplemental Online Material: Cost Analysis of Stratospheric Albedo Modification

year life as well as 10% interest charge for financing over 20 years.
Regional Dispersal
CONOP

Aircraft concept of operations with dispersal taking place in a region close to the
aircraft base. Out and back flight path.

Transit Dispersal
CONOP

Aircraft concept of operations with dispersal taking place during long transit leg
between bases.

Hybrid Airship
(HLA)

An airship that (at some altitude) develops lift from aerodynamics in addition to
buoyancy

Altitudes are expressed in feet in accordance with International Civil Aviation Organization standards. Altitudes for atmospheric chemistry are typically presented in kilometers
so where possible, both feet and kilometers are presented. A conversion table is presented below:

1.2

Thousands of Feet (kft):

40

60

70

80

100

Kilometers:

12.2

18.2

21.3

24.4

30.5

Chemistry Considerations Affecting Dispersal

Atmospheric chemistry analysis as well
as observation of surface temperatures
after large volcanic eruptions has shown
that injection of sulfur compounds into
the stratosphere reduces incoming solar
flux. The mass of sulfur compounds released is directly proportional to the reduction in incoming flux achieved
(Figure 1). Current anthropogenic net
forcing is ~ 2 W/m2.
Figure 1: Reduction in incoming top-ofatmosphere (TOA) solar flux achieved for a
1
given yearly dispersal rate.

For the purposes of this study, a baseline up-mass rate of 1 million tonnes a
year is assumed, equivalent to an estimated reduction in flux of 0.6 to 1.3 W/m2. Additionally, 3 million tonnes (estimated 0.8 to 2.2 W/m2 reduction) and 5 million tonnes (es-

1

Pierce JR, Weisenstein DK, Heckendorn P, Peter T, and Keith DW 2010 Efficient formation of stratospheric aerosol for climate engineering by emission of condensable vapor from aircraft Geophys. Res.
Lett. 37 L18805

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