Monday, December 12, 2011

1062784268.txt

From: "Michael E. Mann" <mann@virginia.edu>
To: Phil Jones <p.jones@uea.ac.uk>
Subject: Re: Something for the weekend !
Date: Fri, 05 Sep 2003 13:51:08 -0400
Cc: Keith Briffa <k.briffa@uea.ac.uk>

sorry, meant "is just the minimum slope" constraint, in first sentence...
apologies for the multiple emails,
mike
At 01:47 PM 9/5/2003 -0400, Michael E. Mann wrote:

Actually,
I think Dave's suggestion "reflecting the data across the endpoints" is really just the
"minimum norm" constraint, which insures zero slope near the boundary. In other words,
he's probably only talking about reflecting about the time axis. I assert that a
preferable alternative, when there is a trend in the series extending through the
boundary is to reflect both about the time axis and the amplitude axis (where the
reflection is with respect to the y value of the final data point). This insures a point
of inflection to the smooth at the boundary, and is essentially what the method I'm
employing does (I simply reflect the trend but not the variability about the trend--they
are almost the same)...
mike
At 01:34 PM 9/5/2003 -0400, Michael E. Mann wrote:

sorry phil, one more relevant item. I've cc'd in Keith on this, since you had mentioned
that you had discussed the issue w/ him.
This is from Dave Meko's (quite nice!) statistics lecture notes:
[1]http://www.ltrr.arizona.edu/~dmeko/notes_8.pdf
See page 2, section 8.1.
He provides two (in reality, as I mentioned before, there are really 3!) basic boundary
constraints on a smooth (ie, in "filtering"). The first method he refers to is what I
called the "minimum norm" constraint (assuming the long-term mean beyond the
boundary). The second, which he calls "reflecting the data across the endpoints", is
the constraint I have been employing which, again, is mathematically equivalent to
insuring a point of inflection at the boundary. This is the preferable constraint for
non-stationary mean processes, and we are, I assert, on very solid ground (preferable
ground in fact) in employing this boundary constraint for series with trends...
mike
At 05:20 PM 9/5/2003 +0100, Phil Jones wrote:

Mike,

Attached some more plots.
1. Figure 7 - Forcing. Guess this is it. Could cut the y scale to -6 and say in
caption that
1258 or 1259 is the only event to go beyond this, then give value in caption. Scale
will then widen out. OK to do ? Caspar's solar now there.
2. Fig 2a - first go at coverage. This is % coverage over 1856-2002 from HadCRUT2v.
3. Fig 4 again. Moved legends and reduced scale. Talked to Keith and we both think
that
the linear trend padding will get criticised. Did you use this in GRL and or Fig 5 for
RoG
with Scott. If so we need to explain it.
On this plot all the series are in different units, so normalised over 1751-1950 (or
equiv for
decades) then smoothed. Again here I can reduce scale further and Law Dome can go
out of the plot. Thoughts ? Think all should be same scale.
Have got GKSS model runs for Fig 8. Were you happy Hans' conditions. If so I'll send
onto
Scott.
Next week I only have Fig 2b to do. This will be annual plot of NH, Europe and CET,
smoothed in some way.
For the SOI I and Tim reckon that it won't work showing this at interannual
timescale with
3 plots. It will then not be like the NAO plot.
Thoughts on colours as well.
Have a good weekend. Logging off once this has gone.
Cheers
Phil
Prof. Phil Jones
Climatic Research Unit Telephone +44 (0) 1603 592090
School of Environmental Sciences Fax +44 (0) 1603 507784
University of East Anglia
Norwich Email p.jones@uea.ac.uk
NR4 7TJ
UK
----------------------------------------------------------------------------

______________________________________________________________
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
_______________________________________________________________________
e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137
[2]http://www.evsc.virginia.edu/faculty/people/mann.shtml

______________________________________________________________
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
_______________________________________________________________________
e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137
[3]http://www.evsc.virginia.edu/faculty/people/mann.shtml

______________________________________________________________
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
_______________________________________________________________________
e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137
[4]http://www.evsc.virginia.edu/faculty/people/mann.shtml

References

1. http://www.ltrr.arizona.edu/~dmeko/notes_8.pdf
2. http://www.evsc.virginia.edu/faculty/people/mann.shtml
3. http://www.evsc.virginia.edu/faculty/people/mann.shtml
4. http://www.evsc.virginia.edu/faculty/people/mann.shtml

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