Friday, May 4, 2012

3799.txt

cc: Fortunat Joos <joosatXYZxyzmate.unibe.ch>, Imprint-WP4 <imprint-wp4@bjerknes.uib.no>, "Crucifix, Michel" <michel.crucifix@metoffice.gov.uk>, "Jones, Chris D" <chris.d.jones@metoffice.gov.uk>, "Hewitt, Chris" <chris.hewittatXYZxyzoffice.gov.uk>, Keith Briffa <k.briffaatXYZxyz.ac.uk>
date: Wed, 23 Feb 2005 13:43:01 +0000
from: "Tett, Simon" <simon.tettatXYZxyzoffice.gov.uk>
subject: Re: Issues to resolve
to: Victor Brovkin <victoratXYZxyz-potsdam.de>

The impression I got was that including C14 in Hadley models was fairly
easy. You would need to define source (solar) at oceanic surface. The
C14 flux could be assumed constant (and well mixed) across the
atmosphere. We get this from the Be10 data. After that C14 is a tracer
(which decays). Total time to implement 1 month or so. I have no feeling
for proxies but had the impression that there was a lot of C14 data
around.....

My worry is trying to do both O18 and C13. Both are tricky and would
need more than 6 months between them. Note we all have to do these
proxies in the same way so might not be able to use our existing code.
My feeling is that for the last 1000 years O18 is the most important and
we should all say we will do that in the same way. C14 is easy so might
as well do that as well. We can add that we will use existing
implementations of C13 -- which requires no resources from IMPRINT.



Anyone have any comments.

Simon
On Wed, 2005-02-23 at 13:17, Victor Brovkin wrote:
> Simon,
>
> we've discussed 14C as a proxy with Fortunat but haven't come to the
> decision whether to include it into task 4.2 and the proxy table or
> not. Obviously, we have 14C in the models already, so the only work
> will be with proxy protocol for oceanic 14C that is easy to take from
> OCMIP. However, we need to explain where exaclty in the proposal we
> will use 14C. One point would be in task 4.6 (THC) where 14C could be
> used as a ventilation proxy but we already have 231Pa/230Th for this
> purpose. Another suggestion would be to use simulated atm.14C as a
> proxy for solar activity (solving inverse task with boundary condition
> from observed atm. 14C) but then we need mentioning of this work in
> the other tasks (WP1) that deal with using Be for solar activity. So,
> we need further integration of 14C into the proposal text and it might
> be not enough time now. Also, we might get critisized for dilluting
> rather thin personal resources among too many proxy developments.
>
> What do you think?
>
> Victor
>
>
>
>
>
>
> Tett, Simon wrote:
> > On Wed, 2005-02-23 at 08:16, joos wrote:
> >
> > > Dear Simon,
> > >
> > > Thanks for working on this.
> > >
> > > 14C as a proxy:
> > > Viktor, we forgot 14C in the proxy table. Need to add this. Bern may
> > > coordinate the proxy protocol. Please modify proxy tables and others
> > > please indicate whether you do 14C in your model.
> > > For the Bern model> 14C: +++
> > >
> > I am concerned that with limited resources we are trying to do too many
> > proxies. (6 months effort would allow about 2 to be implemented...)
> >
> > > 4.3:
> > > I am wondering if we do not need to cover 'the medieval warm period',
> > > e.g. starting at 800 or 850 AD with the GCMs. Anyway, just a thought.
> > >
> > To do it well we'd need to start the simulations 100-200 years earlier
> > (to let the upper-ocean adjust) -- requiring 1500 years of simulation
> > (600-2100). If we started at 1000 (so we could discuss 1200 on) we would
> > only require 1100 years of simulation (and 800 years of high resoln
> > proxy records).
> >
> > > 4.3, 4.4 and 4.6
> > > In Bern we will look with the fast model at CO2, CH4, d13C and 14C (atm,
> > > ocean, land), pollen, ocean 18O, ocean 231Pa/230Th, %CaCO3 as
> > > appropriate within each task.
> > >
> > Is there enough resource to implement the proxies in a consistent way.
> > Is pollen interactive or offline calculations?
> >
> > > 4.4
> > > - CO2: in all fast models
> > > - CH4: Bristol, Bern, PIK?
> > >
> > I think that Hadley might be able to do CH4 from wetlands -- is that
> > sufficient. Michael/Chris(es) can you advise?
> >
> >
> > > - in selected fast models (see proxy table): d13C and 14C
> > > (atm,ocean,land), pollen, %CaCO3.
> > > - GCM snapshots: pollen
> > > (I do not think that we can do more with the GCMs given the
> > > intialisation problem with biogeochemical cycles)
> > >
> > Can we do something clever to get round this? -- some kind of
> > control/perturbation experiment.
> >
> >
> > > Regards,
> > >
> > > Fortunat
> > >
> > > "Tett, Simon" wrote:
> > >
> > > > All,
> > > > thanks for your input so far! I need a bit more from you.
> > > >
> > > > 1) Can I have a description of your models for the table in WP4. (Please
> > > > could Bristol and BCCR fill in the table).
> > > >
> > > > 2) BCCR -- can you you clarify what proxies you plan to simulated and
> > > > fill in the table in 4.2.
> > > >
> > > >
> > > > 3) All -- We need to firm up the following.
> > > > 1) Need some thoughts on what our protocol will be -- are you
> > > > all happy with the current text?
> > > > I think task 4.6/WP3 needs some early experiments to
> > > > identify the hot spots.
> > > > GCM simulations should be limited to the last 1000 years --
> > > > which has some issues for WP1 [Keith would this reduce your budget
> > > > sensibly if you talked about the last 1000 years at high spatial resoln]
> > > > Need to firm up the snap shot simulations -- what do they bring
> > > > to the project....
> > > > 2) Need a minimum set of proxies that all of us will implement.
> > > > Given the (limited) resources we have can I suggest the following.
> > > > a) For models in 4.3 ("recent Holocene") we need delta
> > > > 18 0, 14 C (as it tells us something for ocean proxies) and maybe 13 C
> > > > (though this will be a challenge on the resources available). I am very
> > > > open to guidance from those of you with more expertise than me.
> > > > b) Not sure about the other tasks but could task leaders give me
> > > > views on what proxies are key to their needs. Jerome can I have some
> > > > text on your ice sheet modelling -- other 4.5 modellers can you think
> > > > how to integrate with that work.
> > > >
> > > > 4) Gilles -- can I have some text for 4.6 with deliverables.
> > > >
> > > > Simon
> > > >
> > > > Dr Simon Tett Managing Scientist, Data development and applications.
> > > > Met Office Hadley Centre (Reading Unit)
> > > > Meteorology Building, University of Reading Reading RG6 6BB
> > > > Tel: +44 (0)118 378 5614 Fax +44 (0)118 378 5615
> > > > Mobex: +44-(0)1392 886886
> > > > E-mail: simon.tettatXYZxyzoffice.gov.uk http://www.metoffice.gov.uk
> > > > Global climate data sets are available from http://www.hadobs.org
> > > >
> > > > ------------------------------------------------------------------------
> > > > Name: imprint_wp4.doc
> > > > Type: Microsoft Word Document (application/msword)
> > > > imprint_wp4.doc Encoding: BASE64
> > > > Description: imprint_wp4.doc
> > > > Download Status: Not downloaded with message
> > > >
> >
> >
>
>
> --
> +-----------------------------------------------------+
> | Dr. V. Brovkin |
> | Potsdam Institute for Climate Impact Research |
> | Climate Systems Research Department |
> | P.O.Box 601203, 14412 Potsdam, Germany |
> | Tel.: +49 331 288 2592 |
> | Fax: +49 331 288 2570 |
> | e-mail: victoratXYZxyz-potsdam.de |
> +-----------------------------------------------------+

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