Mike
You asked about how long interventions lasted.
Two periods are involved. The first is the shortest 'coin-tossing' time
between possible changeovers. This is discussed in the section entitled
'Change over period' . We need time for the climate system to respond.
Ben Parkes use 10 days based on being twice the time that reliable
forecasts can be made. However a case could be made for a longer ones
but not long enough to overlap a monsoon period. We might be able to
get a firm number by looking at the corner frequency of sinusoidal
perturbations. This is discussed in the section on 'correlation lag.'
The second is the time for the model run. If an engineer's scanty
knowledge of statistics applies to world climate, the precision of the
coded modulation technique should improve with the square root of the
duration. I used 8310 days (22.75 years) of real daily temperature
records with 16 different artificial temperature modifications for the
first experiment and got a scatter which was 1 to 2 % of the standard
deviation of the record. This would need quite an expensive
thermometer! In order to fool your spam filter I will put the results
into my next email headed 8310 day simulation. Please tell me if it does
not get past a length limit.
Ben used 20 years for his work with a real climate model for each of the
eight separate runs for each of the 89 spray sources. An unfortunate
feature of HadGEM1 is that you have to sum outputs over 10 days and I am
not sure if this is suppressing useful information. You can read more
in chapter 7 of his thesis which you can download from
http://homepages.see.leeds.ac.uk/~eebjp/thesis/
You would not need to repeat runs to study monsoons, just select
sections of the sequence to put into your correlator. However you would
need to use new runs to test tactical spray strategies.
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
On 22/02/2013 19:04, Mike MacCracken wrote:
Hi Stephen--Interesting. I am open to models suggesting my intuition is
inadequate.
One point not very much addressed in the draft paper seemed to me to be how
long one kept the intervention going. Near as I could tell, the paper hardly
mentions, but it seems as if the intervention is running all year long. A
question would seem to be is whether one might see more definitive
connections if one looked on a monthly basis, such that some months would
have more effect than another?
Best, Mike
On 2/22/13 1:13 PM, "Stephen Salter" <[email protected]> wrote:
Mike
As promised.
Stephen
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