cc: John Kennedy , Simon Tett , Susan.Solomon@noaa.gov, Gabi Hegerl date: Wed, 15 Apr 2009 21:15:33 +0100 from: Thomas Crowley subject: Re: trends for n. land (summer) vs globe to: Phil Jones Quoting Phil Jones : I don't want to be posting something on RealClimate.org that is going to create confusion rather than clarification. should I just not submit the piece after all? tom > > John, > Another possible issue is the 61-90 ship based SST normals > for the SH oceans in the range 40-60S. I presume you're working on > improving these for the next version. > > Cheers > Phil > > > At 12:10 15/04/2009, John Kennedy wrote: >> The ARGO data don't go into SST analyses at the moment. They do make >> measurements at depths that overlap with the deeper ship-based >> measurements, so there's no reason why they couldn't be included in the >> future or used as an independent validation of the SST data once the QC >> issues are sorted out. >> >> Drifting buoys measure SSTs about 0.15C cooler than ships (with some >> geographic variation) probably due to predominantly warm biases in the >> ship data. They are included in SST analyses - more than 85% of all SST >> observations now come from buoys - and have probably led to a slight >> underestimate in the rate of warming since the late 1970s when they were >> first introduced. >> >> John >> >> On Fri, 2009-04-10 at 22:29 +0100, Simon Tett wrote: >>> I don't think ARGO goes into the SST dataset though there are a lot more >>> buoys in it. When I was at the Hadley Centre we wondered if buoys were >>> causing a slight cooling trend. [John Kennedy CCed might have some more >>> thoughts on that.] >>> >>> Simon >>> >>> Susan.Solomon@noaa.gov wrote: >>> > Tom >>> > The fact that land could be shown to be warming more than ocean was a >>> > major conclusion of the AR4. >>> > >>> > It's good to see the update to 2008. Quite striking. >>> > >>> > I hate to say this, but I wonder if some of the recent behavior is >>> > spurious - the Argo floats just don't seem very consistent with earlier >>> > records not only for surface temperature but also for sea level (ie >>> > subsurface). What do you think? >>> > Susan >>> > >>> > >>> > ----- Original Message ----- >>> > From: Thomas Crowley >>> > Date: Friday, April 10, 2009 6:10 am >>> > Subject: trends for n. land (summer) vs globe >>> > >>> >> Hi, >>> >> >>> >> I am in the process of producing a new, long (733-1960) paleo >>> >> reconstruction at annual resolution for purposes of better >>> >> validation >>> >> against models. since tree rings are most sensitive to summer half- >>> >> year >>> >> temperatures, and trees usually grow on land, I am calibrating >>> >> against >>> >> 30-90N summer (land), using HadCRU data updated through 2008, >>> >> kindly >>> >> provided by Phil. >>> >> >>> >> some interesting items jump out from just comparing (attached) the >>> >> instrumental reconstructions for 30-90N land, summer vs global >>> >> temps >>> >> (anomalies based on 1960-1990 mean for each data set): >>> >> >>> >> 1) the n summer land changes are almost twice as large (1.5 vs. >>> >> 0.8°C) >>> >> as the global - this is not surprising because we know that land >>> >> heats >>> >> up faster than ocean, but the magnitude is quite striking. >>> >> >>> >> 2) since most people still live on land, this means the human >>> >> impact >>> >> factor has been twice as large as normally assumed for close to 3 >>> >> billion people >>> >> >>> >> 3) the divergence between northern land and global temps seems to >>> >> be >>> >> increasing - both record show the recent decrease in temperatures, >>> >> but >>> >> on land it only started last year (2008) >>> >> >>> >> 4) seven large volcanic eruptions can easily be identified in the >>> >> northern land record - this again makes sense from an energy >>> >> balance >>> >> viewpoint, as summer temperatures are more driven by thermodynamics >>> >> than >>> >> dynamics, so the signal is more easily detectable, especially given >>> >> the >>> >> added impact of maximized reflection of insolation due to high sun >>> >> angle. >>> >> 5) this suggests that northern hemisphere land (summer) might be >>> >> the >>> >> most logical data set to look at for detection of volcanic signals. >>> >> as >>> >> I have nearly finalized the new paleo reconstruction of volcanos, >>> >> it >>> >> might be interesting to re-apply detection and attribution to the >>> >> new, >>> >> longer, and (hopefully improved) data sets. >>> >> >>> >> fyi, Tom >>> >> >>> >> -- >>> >> The University of Edinburgh is a charitable body, registered in >>> >> Scotland, with registration number SC005336. >>> >> >>> >> >>> > >>> >> -- >> John Kennedy Climate Monitoring and Research Scientist >> Met Office Hadley Centre FitzRoy Road Exeter EX1 3PB >> Tel: +44 (0)1392 885105 Fax: +44 (0)1392 885681 >> E-mail: john.kennedy@metoffice.gov.uk http://www.metoffice.gov.uk >> Global climate data sets are available from http://www.hadobs.org > > Prof. Phil Jones > Climatic Research Unit Telephone +44 (0) 1603 592090 > School of Environmental Sciences Fax +44 (0) 1603 507784 > University of East Anglia > Norwich Email p.jones@uea.ac.uk > NR4 7TJ > UK > ---------------------------------------------------------------------------- -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.