cc: , , date: Mon, 15 Apr 2002 21:06:57 -0700 from: "Shaopeng Huang" subject: RE: borehole model driven by surface proxies to: "Edward Cook" , "Tim Osborn" Hi Ed and Tim, I would be surprised if your debate with Mann was not "very lively". A forward calculation using a "known" climate history to model its thermal effect on the rocks does not have any special requirement on the length of the history. A given surface temperature history can always determine a perturbed subsurface temperature profile. However, the calculation is sensitive to the baseline of the surface temperature series. A subsurface thermal anomaly is defined as the deviation from the steady state determined by the heat flow from deeper interior of the earth. The surface temperature baseline is used to determine the steady state. On the other hand, the resolving power of borehole temperature measurements in a climate reconstruction is restricted by the noise level and the diffusive nature of heat conduction. I certainly would like to have the original ECS series, even though it is not scaled to temperature. Indeed, borehole temperatures might be helpful in calibrating a proxy series. I presented a talk on this topic in the IUGG in Birmingham. I appreciate your advice about doing more work before showing off the result. Indeed, the result I showed you is preliminary and "underground". I have recently been tightened up with some non-climate affairs. I have to beg your pardon if I cannot response to your email promptly. Regards, Shaopeng -----Original Message----- From: Edward Cook [mailto:drdendro@ldeo.columbia.edu] Sent: Monday, April 15, 2002 2:14 PM To: Tim Osborn; Shaopeng Huang Cc: k.briffa@uea.ac.uk; p.jones@uea.ac.uk; hpollack@umich.edu Subject: Re: borehole model driven by surface proxies Hi Shaopeng and Tim, Shaopeng, your modeling exercise was rather interesting. I too would like to see your model reconstruct ground temperatures back to the beginning of the ECS series. In so doing, would any hint of the MWP in the ECS series be preserved? I would be happy to provide the annually resolved ECS data for that purpose, although it is not presently scaled to temperatures. As I indicated in an earlier email to a number of people, I am not sure what the "best" solution is to scaling the aggregated tree-ring series to temperatures. However, maybe this is something we can discuss. Certainly, I would be happy to use NH land-only temperatures north of 30N for calibration purposes (maybe north of 20N is okay too). I also agree with Tim that you better have "all your ducks in a row" before showing off your results. Tim, "very lively" is a correct description. I think that things have settled down now, which is good. Ed >At 20:17 14/04/02, Shaopeng Huang wrote: >>Hi All, >> >>As promised earlier, I am sharing you with the experimental results of the >>subsurface temperature anomalies calculated from Espert et al reconstruction >>(ECS) and from Mann et al reconstruction (MBH). Attached is an illustration >>showing the calculated anomalies as compared to the borehole observation. > >Shaopeng, > >The comparison is certainly interesting. Even though the inverse >approach (of using the borehole profiles to estimate post 1500 AD >surface temperatures) can only given estimates for the post-1500 >period, I was wondering whether your approach (of driving a model of >the ground temperature profile with surface proxy reconstructions) >can be applied to the full records (i.e. from 1000 AD, or earlier >for ECS)? If not, then what initial conditions do you specify? >Zero anomaly from a reference profile? Are the results sensitive to >the initial conditions? > >We have been having a very lively (is that the right word Ed & >Keith?) debate with Mike Mann (and Malcolm Hughes) about the ECS >reconstruction and its comparison with MBH. Your comparisons could >certainly contribute to this debate, though I would be wary about >circulating them to Mike without a thorough explanation of the >caveats and uncertainties that are involved in using borehole data >to assess the differences between surface proxy records! In >particular, the data file that I sent you contained smoothed records >that we had re-calibrated against only the land north of 20N, rather >than the full hemisphere (of course, this is almost what you want >for the comparison with boreholes [i.e., no marine data], though you >may want some land south of 20N?). > >Best regards > >Tim > > >Dr Timothy J Osborn | phone: +44 1603 592089 >Senior Research Associate | fax: +44 1603 507784 >Climatic Research Unit | e-mail: t.osborn@uea.ac.uk >School of Environmental Sciences | web-site: >University of East Anglia __________| http://www.cru.uea.ac.uk/~timo/ >Norwich NR4 7TJ | sunclock: >UK | http://www.cru.uea.ac.uk/~timo/sunclock.htm -- ================================= Dr. Edward R. Cook Doherty Senior Scholar Tree-Ring Laboratory Lamont-Doherty Earth Observatory Palisades, New York 10964 USA Phone: 1-845-365-8618 Fax: 1-845-365-8152 Email: drdendro@ldeo.columbia.edu =================================