date: Fri, 15 Jan 1999 11:43:47 +0000
from: SUE TEOH <sue.teohatXYZxyztm.ac.uk>
subject: regional analysis
I think we need to co-ordinate some of our activities along the lines
you/Tim have proposed. I am very keen to be involved and should be
able to contribute a greater (or smaller) amount depending on some
local funding issues. To take your points:
1) another Chinese possibility may be Zong-ci Zhao from the National
Climate Centre of China. She is a lead author in Chapter 9 I think.
2) we should maximise the impact of our work by agreeing to use the
same regions which should benefit WGII also. I agree about keeping
3) again, in order to fit best with other initiatives in IPCC, the
periods should be 1961-90 and 2040-2069 (i.,e., 2050s). If other
periods chosen then they should be 2010-2039 or 2070-2099.
4) Yes, T and P for DJF and JJA is the common starting point.
Diurnal T range may be another good one but not all DDC models have
5) I am obviously in favour of using our data set - the paper on this
will be out in J.Climate this or next month. We think it would be
hard to demonstrate a better choice.
6) The DDC experiments are the obvious ones to use. We now have
results from 7 centres, although not all of them have the same
variables or integration periods for both GG and GS runs. But the
DDC results should form the core of the analysis.
7) this is difficult. I have tended to re-grid everything to the
HadCM2 grid (2.5 by 3.75) since this minimises the amount of
interpolation (i.e., HadCM2 has by far the largest set of results).
I have used GRIDTRAN, which uses a Gaussian space-filter. I
therefore up-scale the CRU dataset to the HadCM2 grid. The
land-coean mask issue is important and we need to be cautious about
over-interpretation. We can discuss this issue more and whether we
need to harmonise.
8) I think there are some separate studies here. At the very least,
one comparing models and observed over 1961-90, one comparing
unscaled scenario changes for the 2050s (although there is a question
whether the 1% DDC runs should be standardised to remove the effect
of climate sensitivity - Ulrich is doing this for Chapter 9 and I
approve), and then one evaluating/presenting the DDC regional changes
after being scaled by the SRES global T scenarios (but global Ts
that *exclude* aerosol effects). This latter is what Tim and I
have started doing for Europe and I have sent you our draft ACACIA
paper which describes this. It is this latter study that is most
relevant for WGII and I/Tim should take the lead on this one.
Tim has some views on your regions.
Other issues to look at include IAV (as you suggest), but also
importantly unforced climate variability in the DDC control runs.
This provides context for attaching significance to scenario changes.
We have explored this issue in our ACACIA work and also in an
impacts paper which is soon coming out in Nature and I believe it is
most important re. scenario and impacts work in WGII. We can discuss
this more, but the DDC models also have unforced simulation results.
Finally is the issue of aerosols. For Study 1 and Study 2 as I
propose above, we can use the DDC aerosol results, but since the
aerosol forcing in these experiments has been discredited by the IPCC
SRES work I do not believe that WGII-based scenarios should use them.
This is why I am in favour of scaling just the GG runs using the
SRES-based global Ts from MAGICC *which exclude aerosol effects*.
There are other ways of handling aerosols which again we can discuss.
Anyway, I think we have a chance to do something really useful here
and certainly count me in.
Department of Epidemiology and Population Health
London School of Hygiene and Tropical Medicine
London WC1E 7HT
Tel: +44 171 927 2254
Fax: +44 171 580 6897