From: "Kevin Trenberth" <trenbert@ucar.edu>
To: "Andrew Revkin" <anrevk@nytimes.com>
Subject: Re: clearing up climate trends sans ENSO and perhaps PDO?
Date: Mon, 7 Jul 2008 20:33:44 -0600 (MDT)
Reply-to: trenbert@ucar.edu
Cc: gschmidt@giss.nasa.gov, mann@psu.edu, davet@atmos.colostate.edu, p.jones@uea.ac.uk, david.parker@metoffice.gov.uk, wpatzert@jpl.nasa.gov, ackerman@atmos.washington.edu, wallace@atmos.washington.edu, tbarnett-ul@ucsd.edu, sarachik@atmos.washington.edu, peter.thorne@metoffice.gov.uk, john.kennedy@metoffice.gof.uk, cwunsch@mit.edu

Andy
Here's some further results, based on the time series for 1900 to 2007

Results:

(0)     correlation between ENSO and PDO: for the smoothed IPCC decadal
filter: 0.490662
(0)     correlation between ENSO and PDO: for the annual means: 0.527169
(0)     regression coef for PDO with global T : 0.0473447
(0)     regression coef for N34 with global T : 0.0664886


Data sources:

;----------------------------------------------
;  PDO:  http://www.jisao.washington.edu/pdo/
;        http://jisao.washington.edu/pdo/PDO.latest
;----------------------------------------------
;  N34:  http://www.cgd.ucar.edu/cas/catalog/climind/Nino_3_3.4_indices.html
;        http://www.cgd.ucar.edu/cas/catalog/climind/TNI_N34/index.html#Sec5
; ---------------------------------
;  CRU:      http://www.cru.uea.ac.uk/cru/data/temperature/
;  Hadcrut:  http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3vgl.txt
;===================================================================
; Files were manually stripped for 1900 to 2007
;============================================/=======================

These numbers mean that for a one standard deviation in the ENSO index
there is 0.066C change in global T, or from PDO: 0.047C, but that much of
the latter comes from the ENSO index.  Very roughly, since the correlation
is 0.5 between PDO and ENSO, half of the 0.066 or 0.033C of the 0.047 is
from ENSO.  Strictly one should do this properly using screening
regression.

Kevin


> dear all,
> re-sending because of a glitch.
>
> finally got round to posting on an earlier inquiry I made to some of
> you about whether there was a 'clean' graph of multi-decades
> temperature trends with ENSO wiggles removed -- thanks to gavin (and
> david thompson) posting on realclimate.
> here's Dot Earth piece with link to Realclimate etc..
> http://dotearth.blogs.nytimes.com/2008/07/07/climate-trends-with-some-noise-removed/?ex=1216094400&en=a57177d93165cba3&ei=5070
>
> next step is PDO. has anyone characterized how much impact (if any)
> PDO has on hemispheric or global temp trends, and if so is there a
> graph showing what happens when that's accounted for?
>
> as you are doubtless aware, this is another bone of contention with a
> lot of the anti-greenhouse-limits folks and some scientists (the post
> 1970s change is a PDO thing, etc etc). hoping to show a bit of how
> that works.
>
> thanks for any insights.
> and i encourage you to comment and provide links etc with the current
> post to add context etc.
>
> --
> Andrew C. Revkin
> The New York Times / Science
> 620 Eighth Ave., NY, NY 10018
> Tel: 212-556-7326 Mob: 914-441-5556
> Fax:  509-357-0965
> www.nytimes.com/revkin


___________________
Kevin Trenberth
Climate Analysis Section, NCAR
PO Box 3000
Boulder CO 80307
ph 303 497 1318
http://www.cgd.ucar.edu/cas/trenbert.html

