Parameters

Minimum set

Reduced set

Standard set

Uncertainty range

1

Injected SO2 mass

X

X

X

5 Tg-S – 10 Tg-S

2

Mid-point height of 3km-thick injection

X

X

X

18km – 30km

3

Latitudinal extent of the injection

X

X

X

Factor 0-1 to vary from 1-box injection at 15N (factor=0) to equator-to-15N (factor=1) *

4

Sedimentation velocity

X

X

Multiply model calculated velocity by a factor 0.5 to 2.

5

SO2 oxidation scaling

X

X

Scale gas phase oxidation of SO2 by a factor 0.5 to 2

6

Nucleation rate of sulfate particles

X

Scale model calculated rate by a factor 0.5 to 2.

7

Sub-grid particle formation factor.

X

Emit fraction of SO2 as sulphuric acid particles formed at sub-grid-scale (0 to 10%)

8

Coagulation rate

X

Scale the model calculated rate by a factor 0.5 to 2.

Groups will need to translate the 0-1 latitude-spread parameter into a sequence of fractional injections into all grid boxes between the equator and 15 °N. For example for a model with 2.5 degree latitude resolution, the relative injection in the 6 latitude bins between 0 and 15N would take the form [0,0,0,0,0,0,1] for extent factor=0, and [0.167,0.167, 0.167,0.167, 0.167,0.167] for extent factor=1. Injection ratios for intermediate values of the spread factor would be calculated by interpolation between these two end member cases.  



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