Friday, June 15, 2012


cc: D�ith� Stone <>, Phil Jones <>, Peter Stott <>, Toru Nozawa <>, Alexey Karpechko <>, Michael Wehner <>
date: Fri, 30 May 2008 16:40:37 +0100
from: Gabi Hegerl <>
subject: Re: Revised polar attribution paper
to: Nathan Gillett <>

Hi all, nature geoscience seems like a good choice to me, and the paper
reads very well.
Similar to Alexey I am a bit ambiguous about showing results with SAM
subtracted only,
given it makes it a little bit harder to interpret. On the other hand,
this is not an issue if
discussed that results are not sensitive to subtracting the SAM, but
that this addresses
the concern if SAM related trends are wellr epresented in the models
Also, the SAM subtracted pattern is
very impressive and could be emphasized a bit more.
I am also wondering why Arctic results are so jiggly with detection
completely lost
for a number of cases with lots of EOFs - do we have any idea why this
is happening?

writing suggestions:
Abstract could mention that temperature trends over Antarctica have been
reported as mixed, raising the question
if Antarctica is not warming as predicted which would have huge
importance on longterm sea level rise prospects. or so
(is this too speculative?)

p. 2 middle, should this explicitly mention that West Antarctica is
still not covered due to hostile conditions?

p. 3 first para: 5-yr average spatial means to avoid two means in short
bottom 2nd line same page, exclusion of these data??

p 4 discussion of simulations: the anthro could be easily (kind of) be
extended with scenarios, right, its the natural that
give us trouble after 1999?

p 5 top, add? 'residual observed trends show warming everywhere
except..pole. THis makes them more similar to the model residual trends
than the raw trends (see supplementary figure 1).'
I am wondering if there is any way to quantify this, for example, by
plotting your sectorial mean data model and obs raw and subtracted as
a line plot, or by plotting zonal means with the peninsula separated as
an extra point? This would also possibly strengthen the case...

on p 6, bottom paragraph, I would also add at the end of the ANtarctica
discussion that
...available and that circulation changes, which were largely
antrhopgenic (citeyourpaper) have reduced warming rates over parts of
Antarctica in models and observations
in the past' does ch10 say something about futur, I think consistent
warming is expected in future? (the time intensive approach would be to
get the
data for the future anthro runs and plot a bit into the future as well
which might make this paper hotter for nature but I admit it does sound
like work....)


Nathan Gillett wrote:
> Hi all,
> Please find attached a revised version of the polar attribution paper,
> and supplementary info. In response to your earlier comments and
> suggestions, I've made the following changes:
> - I now subsample the monthly model data at observed locations, rather
> than doing the sampling on 5-yr means.
> - I mask the model data with its land mask, before applying the
> analysis, so that I'm comparing observed land temperatures with
> simulated land temperatures (except in the case of cells in which the
> model has no land, but observations exist, in which case I take the
> mean over the whole cell).
> - I've applied the D&A analysis to the SAM-residual temperature
> changes (see supplementary info).
> - I haven't applied the analysis to data to the present, because the
> data doesn't seem to be available yet.
> Subsampling the monthly model data makes the attribution analysis
> slightly less robust to variations in truncation, but we can still
> detect ANT. Applying the analysis to the SAM residual makes it easier
> to detect ANT in the Antarctic.
> I'm inclined to submit this to Nature Geosciences, partly since it's
> new and makes a change from GRL, and partly since I won't have to
> reformat it to submit there... Let me know if you disagree. Comments
> welcome - it would be good to get this resubmitted soon.
> Cheers,
> Nathan

Dr Gabriele Hegerl
School of GeoSciences
The University of Edinburgh
Grant Institute, The King's Buildings
West Mains Road
Phone: +44 (0) 131 6519092, FAX: +44 (0) 131 668 3184

The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.


No comments:

Post a Comment