cc: Susan Solomon , John Lanzante , Melissa Free ,Dian Seidel , Tom Wigley ,Karl Taylor , Thomas R Karl ,Carl Mears , "David C. Bader" , "'Francis W. Zwiers'" , Frank Wentz , Leopold Haimberger , "Michael C. MacCracken" , Phil Jones , Steve Sherwood , Tim Osborn ,Gavin Schmidt , "Hack, James J." date: Thu, 17 Jan 2008 14:17:59 -0800 from: Stephen Klein subject: Re: The minus 1 (.png or .ps.gz) to: Peter Thorne , Ben Santer Peter et al., Thanks for this figure updating Santer et al. 2005. Although I am a bit rusty on this subject, there are two questions I have: 1) Does anybody have an explanation why there is a relative minimum (and some negative trends) between 500 and 700 hPa? No models with significant surface warming do this, and I can't think of a plausible physical reason for this. Do people feel the relative cooling of this layer relative to the surface is robust? 2) Have you thought of producing a comparison of models to radiosonde observations for a longer term trend (late 1950s to 1999)? My recollection (from when I worked with John L. and Dian S.) is that the tropical radiosonde upper troposphere temperature trends were a bit stronger over the longer-term. Even if you add this to the paper, it might be nice to examine a figure of this type for the longer period to assess models, and perhaps comment on in the paper. Steve At 02:56 AM 1/17/2008, Peter Thorne wrote: >First hack at a caption: > >Figure 6. Tropical trends from all available radiosonde products for >1979-1999. Trends have been calculated by zonally averaging the gridded >data; applying a cos(lat) weighting to this zonal profile over 20N to >20S to create a tropical mean timeseries; and then calculating a trend >from this timeseries using a median of pairwise slope estimator that is >robust to outliers (Lanzante, 1996). For RATPAC-A, which consists of a >much sparser network, the tropical mean timeseries available from their >website has been used to calculate the trend. Also shown are theoretical >expectations based upon the assumption that the tropical troposphere >behaves as a moist adiabat and climate model mean and 2 sigma estimates >as to what the true trend should be. Both these estimates are derived >from Figure 3 B of Santer et al. (2005), scaled by the available surface >estimates (taken from Santer et al., 2006). The implicit assumption is >made that these estimates adequately portray the real surface changes. > >I'm away Friday and Monday so will look afresh based upon accrued >comments on Tuesday and make any mods then. > >My thanks to Leo for all of his hard work to provide the RAOBCORE >products to me to calculate the trend values for this figure. And my >apologies that my temperamental computer served to delay this by 24 >hours ... (don't ask!) > >Peter >-- >Peter Thorne Climate Research Scientist >Met Office Hadley Centre, FitzRoy Road, Exeter, EX1 3PB >tel. +44 1392 886552 fax +44 1392 885681 >www.metoffice.gov.uk/hadobs > >