cc: Scott Rutherford date: Tue, 20 Jan 2004 12:27:56 -0500 from: "Michael E. Mann" subject: Re: J. Climate paper - in confidence to: "Malcolm Hughes" , Keith Briffa , "Malcolm Hughes" , Tim Osborn ok--thanks a bunch for the clarification Malcolm, mike At 10:27 AM 1/20/04 -0700, Malcolm Hughes wrote: >Mike - you are right that we should probably leave the network >uncahnged for this mss. In fact, however, as Keith indicated, the >Vaganov data probably retained a fair amount of low frequency >because of the use of the corridor method (i.e. were not "heavily >standardized"). CHeers, Malcolm >On 20 Jan 2004 at 7:58, Michael E. Mann wrote: > > > Thanks Keith, > > > > I agree w/ this--I think the Vaganov chronologies were pretty heavily > > standardized, and the other issues you raise are important. In the > > future, we would (and will) be a bit more circumspect about the use of > > some of these data. > > > > In the present case, however, I think we are forced to use the exact > > same network. > > > > Re, the omission of some results. I think we can probably keep them. > > Simply by cleaning up the text, removing redundancy, etc. I've > > shortened and tightened the manuscript considerably, and I think I've > > improved the logical flow a bit in the process. So my feeling is that > > we will not have to split this up, but I'll leave this to all of you > > to decide after you see the revised draft from Scott and me... > > > > Thanks, > > > > mike > > > > At 09:45 AM 1/20/2004 +0000, Keith Briffa wrote: > > Malcolm seems to have done a good job sorting out these > > constituent sets , and I don't have anything to add other than > > agreeing that as a general principal , where possible, original > > chronologies should be used in preference to reconstructed > > temperature series ( the latter having been already optimized > > using simple or multiple regression to fit the target temperature > > series ). This applies not only to our western US reconstructions > > (which it should be stressed are based on very flexible curve > > fitting in the standardisation - and inevitably can show little > > variance on time scales longer than a decade or so) but also to > > the Tornetrask and Polar Urals reconstructions (each of which was > > based on ring width and density data , but standardised to try to > > preserve centennial variability - though the density series had by > > far the largest regression coefficients). There is though a > > question regarding the PCs of the Siberian network (presumably > > provided by Eugene?) . The correlation between density and ring > > width can get high in central and eastern parts of the network , > > so even though these are different variables , it might not be > > strictly true to think of them as truly independent > > (statistically) of the density chronologies we use from the > > Schweingruber network ( there may also be a standardisation issue > > here , as the density chronologies were standardised with > > Hugershoff functions for our initial network work (as reported in > > the Holocene Special Issue) whereas your PC amplitudes may be > > based on "Corridor Standardisation" - which likely preserves less > > low frequency? ) . These remarks are simply for clarification and > > discussion , and I too will wait on your response draft , though I > > would throw in the pot the fact that omitting the time dependent > > stuff would simplify the message at his stage. cheers Keith > > > > At 01:42 PM 1/19/04 -0700, Malcolm Hughes wrote: > > Mike - there are the following density data in that set: > > 1) 20 Schweingruber/Frttss series from the ITRDB (those that > > met the criteria described in the Mann et al 2000 EI paper) > > 2) Northern Fennoscandia reconstruction (from Keith) > > 3) Northern Urals reconstruction (from Keith) > > 4) 1 density series for China (Hughes data) and one from India > > (also Hughes data) - neither included in Keith's data set, I > > think. 5) To my great surprise I find that you used the Briffa > > gridded temperature reconstruction from W. N. America > > (mis-attributed to Fritts and Shao) - of course I should have > > picked up on this 6 years ago when reading the proofs of the > > Nature sup mat. It was my understanding that we had decided not to > > use these reconstructions, as the data on which they were based > > were in the ITRDB, and had been subject to that screening process. > > So depending on whether you used the long or the shorter versions > > of these, there will have been a considerable number of density > > series included , some of them twice. It means that there is > > considerably more overlap between the two data sets, in North > > America, than I have been telling people. I stand corrected. > > Cheers, Malcolm . .Malcolm Hughes Professor of Dendrochronology > > Laboratory of Tree-Ring Research University of Arizona Tucson, AZ > > 85721 520-621-6470 fax 520-621-8229 > > > > -- > > Professor Keith Briffa, > > Climatic Research Unit > > University of East Anglia > > Norwich, NR4 7TJ, U.K. > > > > Phone: +44-1603-593909 > > Fax: +44-1603-507784 > > > > http://www.cru.uea.ac.uk/cru/people/briffa/ > > > > ____________________________________________________________ > > __ > > Professor Michael E. Mann > > Department of Environmental Sciences, Clark Hall > > University of Virginia > > Charlottesville, VA 22903 > > ______________________________________________________________________ > > _ e-mail: mann@virginia.edu Phone: (434) 924-7770FAX: (434) 982-2137 > > http://www.evsc.virginia.edu/faculty/people/mann.shtml > >Malcolm Hughes >Professor of Dendrochronology >Laboratory of Tree-Ring Research >University of Arizona >Tucson, AZ 85721 >520-621-6470 >fax 520-621-8229 _______________________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137 http://www.evsc.virginia.edu/faculty/people/mann.shtml