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cc: Brian Soden <REDACTED>, Panmao Zhai <REDACTED>, Roxana Bojariu <REDACTED>, David Parker <REDACTED>, Jim Renwick <REDACTED>, Albert Klein Tank <REDACTED>, Fatemeh Rahimzadeh <REDACTED>, Matilde Rusticucci <REDACTED>, Peter Ambenje <REDACTED>, Byron Gleason <REDACTED>, Jay Lawrimore <REDACTED>, David Levinson <REDACTED>, Richard W Reynolds <REDACTED>, Tom Smith <REDACTED>
date: Tue Dec 21 16:38:03 2004
from: Phil Jones <REDACTED>
subject: Re: Map questions
to: Kevin Trenberth <REDACTED>, David Easterling <REDACTED>

David, Kevin,
REDACTEDThanks for the EOS pdf Dick. The colour schemes that look good in its Fig 2
are D for temperature and C for precip (if the blue gets changed to a green). The blue
would
be better for colour blind people.
I too don't see why the schemes should be symmetrical. The temperature ones
certainly will not as we're choosing the periods to show warming.
REDACTEDWe seem to be agreeing on having two other colours (one for nearish to zero
anomalies and for missing). If we go with your globally complete dataset, then this
only means missing is over the oceans for precip - except for the confidence in the
trends in data sparse regions. So I'd go for white (no colour) for missing as this will
mean the oceans are blank for precip. Nearish to zero trends then have to be grey.
REDACTEDDetermining the contours is then the only issue - I prefer nice round numbers.
Nearish to zero has then to be something like +/- 0.05 deg C/decade or +/- 0.2 deg
C/century.
Hopefully this are will encompass about 10-20% of the map.
I would like to see all seasons and the year with the same scale forREDACTEDfor
temperature and similarly for precip. This means that trends in the different seasons
can be intercompared.
All just thoughts after a long tiring day !
Cheers
Phil
With this if trends were per century forREDACTEDthen the scales might be quite
similar.

At 15:50 21/12/2004, Kevin Trenberth wrote:

Hi David
My own preference for color schemes is to have something that in Fig 3.4.2.2 where the
near zero anomaly is white. This means some other color (speckled gray perhaps) has to
be used for missing data. The idea behind this is that the values near zero are not
significant. This color scheme was one recommneded in Eos a short time ago: it is good
for people who are color blind. With color one can also let the colors saturate at some
point, so all values beyond a certain value are one color. This can cut down on some
noise at individual points. Often it is convenient to straddle the zero with the
contours and thus not plot the zero line, which can meander all over the place. Other
viewpoints welcomed.
I don't see why the color schemes should be symmetrical, especially for a skewed field.
It is desirable to have some color coding such as warm colors for positive and cold
colors for negative. For precip it is often greens vs browns for wet vs dry.
David Easterling wrote:

All,
We just had a meeting here at NCDC for the map figures that raised some
questions/issues
we must resolve. These are:
1. for the maps do we want a neutral color bounding + or - some value around zero to
show no real trend as Kevin has suggested or have the color scheme start with the first
positive or negative value (e.g. for temperature have anything positive start with the
red
scheme or anything negative start with the blue scheme)?
2. for the scales, do they need to be symmetrical on either side of zero or can the
range
from the lightest to darkest color for positive be different than for negative? For
example
the range for precipitation go from 0 to 100% for positive (green) but go from 0 to -50%
for negative?
3. for the Smith-Reynolds temperature data set problem in the polar and data sparse
regions, we
can use the confidence value supplied with the data and set a confidence threshold for
whether we
use a particularly grid point trend value or make that grid point missing. Tom Smith is
looking at what the value should be and it will take a few weeks to work this out
properly.

For color one can also use semitransparent and lightly mask less confident areas rather
than wiping them out.

4. For theREDACTEDmaps should the trends be in deg or % per century or per decade?
The
REDACTEDmaps will be "per decade".

Depends on quantity. For some fields one needs to know both and the area averages are
not transferable from one to the other with a simple constant. That is the case for
water vapor in FigREDACTEDWe have both mm/decade and %/decade. The former emphasizes
the tropics. It is most impt for the actual hydrological cycle. But the latter is more
impt for RH and allows the plot to be global with a linear scale. I suspect the same is
true for precip.

5. The color schemes will be modified to make the darker colors more bold (e.g. brighter
red).

Check out the article in Eos a few weeks ago.

Byron Gleason is making up some examples of maps addressing these questions for review.
In particular
the symmetrical vs non-symmetrical scale, and the neutral color to indicate no trend.
Jay Lawrimore did
the maps for the TAR and may have more information or questions.
Dave
Phil Jones wrote:

Kevin,
REDACTEDThese use the spatially infilled dataset of Smith and Reynolds (2005). This has
problems in earlier years. I've yet to see the paper, but it is due out in J. Climate
quite soon. The problem in the earlier years is commented upon in section 3.2.
REDACTEDWe can work on these plots a little more. The break could be 120E - this keeps
the Pacific and Atlantic together.
My hope was for theREDACTEDplots to be in change per century with those for
REDACTEDin change per decade (change being deg C or % for precip). In change
per decade forREDACTEDthe overall change is 10.3 times the change shown.
I did comment about the precip trends looking odd. They do look a lot better than
the first draft ! There is another plot from Dave in the other file - page before Fig
REDACTED
This shows how hairy these trends are.
The temperature ones use the same colour scheme for all seasons for the same
period. I quite the temperature ones , but the precip scale needs to be done like
the temperature - clear breaks between each colour, rather than the gradual change
at present.
REDACTEDDave - is there a chance for another iteration before Jan 14 - or earlier ? I know
you don't have so much time off as we do here ! I'll be off from Dec24-Jan3 inclusive.
I will be checking email from home. We haven't just had Thanksgiving though !
Cheers
Phil
At 15:45 16/12/2004, Kevin Trenberth wrote:

Phil, Dave
This is the first time I have seen these figures. Firstly let me say I like the
projection, and it works great with land data. I personally prefer to have the dateline
in the middle as this highlights the ENSO stuff.
However, I am not enarmoured with the color scheme and some units must be wrong??? Are
there no missing data in the first figure on T trends fromREDACTEDThere must be,
over Antarctica, southern oceans etc????
Then for the precip trends the units are blocks of 20%/decade???
So for 1901 to 2003 it means over 10 decades and the values for the lowest contour is
200%??? Even for the last 30 years the lowest contour range is 0 to 60%!!! I do note
that mostly only one color makes it on either side of zero, but these units make no
sense whatsoever.
My own preference on all these kinds of plots is to have some nodescript color
straddling zero where trends are not significant.
But these need to be distinguished from no data.
Why is it labeled "IPCC trend"?
This is my quick feedback
Kevin
Phil Jones wrote:

Same email with NCDC figures

Dear All,

REDACTEDLater today I'll send the current version of the text and the references. I'm
sending
the Figures now. There are 2 sets of figures. The first is all those currently numbered
in the draft text. Most have captions (which repeat in the text in Kevin's sections). I
will
add those captions from 3.2/3.3/3.8 in this fashion in early January. I'll send this
again in zipped format.
REDACTEDThe second file is 20 global plots of temp/precip trends forREDACTED
andREDACTED(4 seasons + year =5 *2 periods*2 variables =20). Not all these
will be in the ZOD, but a selection will. This file doesn't compress at all well,
so if you don't get it email Dave Easterling to see if he can put it on a server at
NCDC. All were produced by Dave and Byron Gleason. Once NCDC (Russ Vose)
have finished their next version of the max/min/DTR dataset, plots like this will
be produced for that as well. The temperature plots are all spatially infilled
(see Smith and Reynolds, 2005). This has its problems for theREDACTED
period, but forREDACTEDis OK (and for this it should use blended SST estimates
for satellites).
REDACTEDSo 3 emails (including this one coming now). Sending now to allow a few hours
for bounces to occur. The text and figs are much, much smaller.
REDACTEDThis email - numbered figs in doc format
REDACTEDNext email - same file zipped
REDACTEDThird email - NCDC plots in doc format.
REDACTEDThe email with the text will have more details about the timetable.
Cheers
Phil
Prof. Phil Jones
Climatic Research Unit Telephone +44 (0)REDACTED
School of Environmental Sciences Fax +44 (0)REDACTED
University of East Anglia
NorwichREDACTED Email REDACTED
NR4 7TJ
UKREDACTEDREDACTEDREDACTEDREDACTED-----

--
****************
Kevin E. TrenberthREDACTEDREDACTEDe-mail: REDACTED
Climate Analysis Section, NCARREDACTED[1]www.cgd.ucar.edu/cas/
P. O. Box 3000,REDACTEDREDACTED(303) 497 1318
Boulder, COREDACTEDREDACTED (303)REDACTED(fax)
Street address: 1850 Table Mesa Drive, Boulder, CO 80303

Prof. Phil Jones
Climatic Research Unit Telephone +44 (0)REDACTED
School of Environmental Sciences Fax +44 (0)REDACTED
University of East Anglia
NorwichREDACTED Email REDACTED
NR4 7TJ
UK
REDACTEDREDACTEDREDACTEDREDACTEDREDACTED

--
****************
Kevin E. TrenberthREDACTEDREDACTEDe-mail: REDACTED
Climate Analysis Section, NCARREDACTED[2]www.cgd.ucar.edu/cas/
P. O. Box 3000,REDACTEDREDACTED(303) 497 1318
Boulder, COREDACTEDREDACTED (303)REDACTED(fax)
Street address: 1850 Table Mesa Drive, Boulder, CO 80303

Prof. Phil Jones
Climatic Research Unit Telephone +44 (0)REDACTED
School of Environmental Sciences Fax +44 (0)REDACTED
University of East Anglia
NorwichREDACTED Email REDACTED
NR4 7TJ
UK
REDACTEDREDACTEDREDACTEDREDACTED--------