date: Fri, 23 Dec 2005 16:12:23 +0000 from: Gerard van der Schrier subject: first version of ms. to: Tim Osborn , Keith Briffa Tim & Keith, Attached is a first version of a ms. about the optimal fingerprinting technique, and an application to relate changes in sea-surface height (SSH) to changes in oceanic meridonal heat transport (MHT). There are two major differences with an earlier version we discussed some time ago. The estimates of trends in MHT from trends in SSH is beefed up some more. The correlation between observed and estimated changes in MHT is now 0.71, which is not too bad. The 95% confidence levels decreased to 1.39, which is still pretty large (the trends in MHT are normalized, so the confidence limits are 1.39 sd.......). On the other hand, this would relate to a trend of 0.039 PW/yr. Bryden et al. recently found a change over the 1990s of 0.33-0.5 PW/yr. The other thing is that my estimate of a change in MHT over the 1990s, based on altimetry data, is now negligable. This is not necessarily a bad thing. Knight et al. (2005) recently estimated an *increase* in MHT, Bryden et al estimated a *decrease* and Carl Wunsch has a submitted paper in which he estimates the change in MHT to be negligable too. The ms. still feels a bit 'thin'. I've tried two approaches to extent this analysis. One was Tim's suggestion to look at trends of 5, 20 and 40 years too. You see that the skill of the method increases somewhat when the length of the trend is increased to 20 years, to decrease again for 40 years. The improvement in skill, and the associated decrease of the size of the confidence limits, is not very impressive. The other way was to use multiple patterns to estimate trends in MHT. For some reason, this did not yield better estimates of MHT compared to the univariate approach. This is somewhat counter-intuative though. I don't know why the skill does not improve. Cheers, Gerard -- ---------------------------------------------------------- Gerard van der Schrier Royal Netherlands Meteorological Institute (KNMI) dept. KS/VO PO Box 201 3730 AE De Bilt The Netherlands schrier@knmi.nl ---------------------------------------------------------- Attachment Converted: "c:\eudora\attach\artv13.pdf"