November 2012

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darrog
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Re: November 2012

Post by darrog » Wed Dec 19, 2012 11:13 am

Paul - I think that you mentioned this before.

however, when a mean works out at .05 I always round up, regardless of whether it is .15, .25, .35, etc.

i imagine the thinking of 'one up, one down' must simply be to compensate for the 'average' 6 occassions a year when you would have a mean of 0.05 - so that by average, 3 go up and 3 come down and eh a balanced figure - but would it really work like that.
Now writing and thinking at the same time, see I can multi-task, I do see an element of sense, but I guess that I won't change.
however, it also ignores the rounding up/down of the mean min/max and that will effect if the final mean is bang on 0.1 or a 0.05 - now I see less sense.
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Paul C
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Re: November 2012

Post by Paul C » Wed Dec 19, 2012 12:35 pm

Those "rules" I understand are Met O rules - so they really should be used. Now whether they make a difference overall I dont know, stick to one method. But we should always follow the standard.

I enjoy recording the data more than I understand the actual weather, but as I am not that mathematically minded I dont really want to get to hung up on a 0.1c degree here and there . Am I right to think this way ?

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Re: November 2012

Post by darrog » Tue Dec 25, 2012 8:47 pm

So how do you work out seasonal and yearly averages then?

A - the sum of the mean temps divide by 12 and then apply those rules re 0.05, 0.15, etc or

B - the sum of the mean min/max divide by 2 and then apply the above rules?

i should add that all means in COL use A

i will give my yearly figures as an example of how this matters.

2009
using A above my yearly mean would = 8.83c (8.8c)
Using B above my yearly mean would = 8.85c - which then becomes 8.9c


2010
using A above my yearly mean would = 7.39c (7.4c)
Using B above my yearly mean would = 7.35c - which then becomes 7.3c

So it does matter and I know which I prefer (A), but I bet you tell me B
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Paul C
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Re: November 2012

Post by Paul C » Wed Dec 26, 2012 1:10 pm

In short YES - same rules apply

Would you not get the same result though using either A or B Method ?

Unless Carl has another take on it ?

I am now in a state of "what do I do" I think my means are a mixture of the "rule" the early years and then when my spreadsheet calculations take over

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Re: November 2012

Post by darrog » Wed Dec 26, 2012 3:46 pm

Paul - with the end of the year coming up that's why i asked.

I applied your system to my data and it changed a number of months - but then I thought about the years..

After making those changes using your system I then checked out the effect that they had on the years.

first I used A - this changed one year

then i used B - and this changed two of the years but not the year that A changed!!!!

It should not be this complicated

EDIT - just checked the Met'O site for historical averages at Newton Rigg
Mean yearly max' for 1981-10 - total of 12 max's = 148.1 divide by 12 = 12.34 - they show 12.4 !!!!!!!!
Mean yearly min for 1961-90 - total of 12 mins = 55.7 divide by 12 = 4.64 - they show 4.7 !!!!!!!!

can you explain?
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Paul C
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Re: November 2012

Post by Paul C » Wed Dec 26, 2012 6:29 pm

?
Is there Min 55.7c yours or there figure

Looks like on the evidence you put forward they have made a mistake then, cant round up 12.34 to 12.4, that would never work either in basic maths rules or Meto rules

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Re: November 2012

Post by Carl M » Wed Dec 26, 2012 6:59 pm

Always use your ''A'' rule.

Not sure how the Met O came to those figures, worth sending them
a cheeky email then :lol:
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Re: November 2012

Post by darrog » Wed Dec 26, 2012 7:22 pm

Carl - thanks and will e-mail the Met'O - may even ask them thi same Q.

I do think that for a yearly mean that A works best.

I have also put something on COL's forum to see the response from there.

paul - would it be worthwhile putting these few posts re mean temps onto a new topic of its own?
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Re: November 2012

Post by Paul C » Wed Dec 26, 2012 8:07 pm

YES - may be best will see If I can start a new thread.

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