date: Tue, 15 Feb 2005 17:32:14 +0100
from: Valerie Masson-Delmotte <Valerie.MassonatXYZxyz.fr>
subject: Re: IMPRINT task 1.1 coming together
to: Tim Osborn <t.osbornatXYZxyz.ac.uk>
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Tim Osborn wrote:
> Dear Jean, Carlo and Jerome,
> ok, so there is a strong scientific case for the dust size studies
> with Antarctic ice cores. I note that the papers mentioned focus on
> pre-10k BP and pre-2k BP periods so far - presumably you suggest to
> now analyse data for the last 2000 years too? (Otherwise it isn't
> relevant for task 1.1).
> If we keep it in task 1.1, is there any overlap between LGGE and UMB
> (Milan) that could result in reduced budget requests? And is the
> high-resolution stratigraphy task listed under UMB necessary to get
> the dating of these dust size records? Or is that independent work
> that could be dropped? Finally, is Talos Dome simply another name for
> Taylor Dome (sorry for my ignorance!).
> Best wishes
> At 13:47 14/02/2005, petit wrote:
>> Dear Tim,
>> In response to your comment nb 2 and 8 from document Task 1 section
>> B4 and B8 to remove the dust studies from task 1.1 to reduce budget,
>> I would like advocate for having dust project studies as part of
>> Recent works on dust studies from Antarctic ice cores have changed
>> our view on the climate variability over the east Antarctic plateau,
>> but unfortunately yet not widely known.
>> Variability in dust size parameters during Holocene(signal/noise
>> ratio) is indeed well higher and significant than other climate
>> proxies (e.g. stable isotope, ...). Moreover the dust size differs
>> from the total dust concentration and is almost only dependant on the
>> atmospheric circulation modes (Delmonte et al., 2002, 2004, and in
>> press ).
>> During the last deglaciation and the Holocene period, it was shown
>> the size distribution changes have been associated to the (pseudo
>> oscillating) shifts of the polar vortex over East Antarctica between
>> Dome region and Vostok region (Delmonte et al., 2004, and in press ).
>> Moreover, during Holocene (up to 3000 BP ) significant secular to sub
>> millennial and secular periodicities are present in the dust records
>> with a dominant 200 year (solar?) period which is common to all
>> records (Delmonte et al, in press, attached).
>> Note also that such spectrum of climate sub millennial and secular
>> variability in Antarctica (prior 3000 BP) seems consistent with NH
>> variability of the last 2000 years as recently presented by Mobek et
>> al, Nature, feb 10, 2005, .
>> GCM have been indeed used to assess the observed recent climatic
>> change over Antarctica (warming Peninsula and cooling East Antarctica
>> and the shift in the polar vortex) and associated due to the recent
>> ozone depletion (e.g. papers from Solomon and Thompson � in Science).
>> The proposed task aims to document the 0-2000 BP period in Antarctica
>> from existing ice cores and pits, with the ambition to compare with
>> the natural forcings from solar variability (10Be) and volcanic
>> input.Our task is also to generate dust data from pits and shallow
>> cores covering the instrumental period.
>> Dust size studies are currently developed at Laboratory of Glaciology
>> (LGGE) with collaboration with University Bicocca, Milano for coulter
>> counter measurements and also University of Berne and AWI Bremerhaven
>> are using laser system for flow-line analysis
>> I strongly advocate for having this project part of IMPRINT which
>> appear relevant to tasks1.1 task 1.2, and task 1.5.
>> Without this support our European community will not be able to
>> continue this original and promising research.
>> Sincerely yours
>> Jean Robert Petit
>> Jean Robert PETIT
>> LGGE-CNRS BP 96
>> F-38402 St Martin d'Heres Cedex
>> Tel: +33 (0)4 76 82 42 44
>> Fax: +33 (0)4 76 82 42 01
> Dr Timothy J Osborn
> Climatic Research Unit
> School of Environmental Sciences, University of East Anglia
> Norwich NR4 7TJ, UK
> e-mail: t.osbornatXYZxyz.ac.uk
> phone: +44 1603 592089
> fax: +44 1603 507784
> web: http://www.cru.uea.ac.uk/~timo/
> sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm
Dear Jean Robert, Carlo, Jerome,
Are you really sure that the dust variability goes into 1.1 and should
not it go into 1.2 because of the resolution of the records (decadal
variability at best)?
I think that the data are really important in terms of changes in vortex
and response to forcings such as irradiance at the centennial time scale.
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