cc: mmanning@al.noaa.gov, wg1-ar4-ch06@joss.ucar.edu, v.ramaswamy@noaa.gov, p.m.forster@reading.ac.uk, Marquis@ucar.edu, Renato Spahni date: Fri, 3 Feb 2006 15:03:26 -0700 from: Jonathan Overpeck subject: Re: [Wg1-ar4-ch06] [Fwd: Greenhouse Gas Figure for IPCC] to: Valerie.Masson@cea.fr Hi Valerie et al. - let's all weigh in before Renato generates the final SOD graphic. My thoughts 1) I don't feel strongly about the delta D data being smoothed or not (it makes sense, but will it make a difference? - go ahead if others agree), but I think we should keep isotopic data, rather than temperature - to avoid the confusion with the most recent data not being the warmest - or even close. It's regional temp, I know, but some readers might realize this. We can say in the caption that delta D is a regional temp record. I'm just one vote, here... 2) I agree with the vert grey shaded areas, and will go one step farther for a compromise. I vote we keep the shading on the real interglacials of the last 450kyrs, and delete the grey shading on the earlier "interglacials" - they are different, clearly, and we can make that point in the caption. Valerie's reasoning then works the other way - the grey shading helps readers get the point about how the length of interglacials comparable to the Holocene have varied, with MIS 11 being the phattest. Thanks, Peck >Jonathan Overpeck a écrit : > >>Hi Fortunat, Renato and friends: Here's my >>thoughts on what you have sent wrt to chap 6: >> >>1) for the EPICA/VOSTOK figure, I agree we >>should go with the version WITH N2O and WITH >>the anthropogenic increase >>(ipcc_ghg650kyr_v1ant) Renato - would you >>please resend with the delta D label fixed. >>Thanks - otherwise, nice job. >> >> >I have a few comments on the figure ipcc_ghg650kyr_v1ant. > >- the deuterium data should be smoothed to >appear with a resolution similar to the GHG >records (we usually use step functions for >deuterium plots because the measurements are >conducted as averages for bag samples => not >single points). > >- it is possible to show temperature >fluctuations rather than deuterium, if you >prefer. > >- I am worried about the vertical grey lines on >this figure, assumed to define "interglacial >periods". It is tricky and depends on some >hypothesis (thresholds on deuterium or GHG). For >instance stage 7.5, 7.3 should also appear as >interglacials with the thresholds used for the >other warm periods. >As we are aware of (preliminar) Dome C age scale >problems for stages 13-15, the grey bars may >give false impressions regarding the duration of >the oldest warm episodes. > >Valérie. -- Jonathan T. Overpeck Director, Institute for the Study of Planet Earth Professor, Department of Geosciences Professor, Department of Atmospheric Sciences Mail and Fedex Address: Institute for the Study of Planet Earth 715 N. Park Ave. 2nd Floor University of Arizona Tucson, AZ 85721 direct tel: +1 520 622-9065 fax: +1 520 792-8795 http://www.geo.arizona.edu/ http://www.ispe.arizona.edu/ _______________________________________________ Wg1-ar4-ch06 mailing list Wg1-ar4-ch06@joss.ucar.edu http://www.joss.ucar.edu/mailman/listinfo/wg1-ar4-ch06