cc: i.harris@uea.ac.uk,  "Tett, Simon" <simon.tett@metoffice.gov.uk>
date: Tue Aug 30 11:25:59 2005
from: Phil Jones <p.jones@uea.ac.uk>
subject: Fwd: sorry about this review
to: "Brohan, Philip" <philip.brohan@metoffice.gov.uk>, "Kennedy, John" <john.kennedy@metoffice.com>

    Philip,
        I had a more detailed look at the comments over the long weekend.
    Here are a few thoughts.
    1. If you want to know more about the structural uncertainty, that Tom P.
    is talking about, then talk to either Peter Thorne or David Parker. This
    term seems to have become widespread with the CCSP meetings on
    the lower tropospheric/surface temperatures differences. Basically, it
    is that errors don't include the effects of assumptions made in the
    dataset construction. So, when you get new or modified data, such
    as the revised SST data around WW2, the new data shouldn't change
    things more than the earlier error estimates - if these were correct.
    2. It would seem that the error bars appear too small for SST. I said
    after the quick read, that I didn't think any more work is needed, but
    I think you are going to have to add two things. First, it will be necessary
    to produce HadCRUT3v a different way (the old HadCRUT2v way) of
    merging the land and marine components - just to show that it
    makes very little difference. Second, some comparison of the Smith
    and Reynolds dataset and its error bars will have to be included.
    The problem you'll find with SR, is that they have infilled data
    everywhere, so their long-term trends are smaller, because
    the infilling is mostly with near zero values, so the 1880-1920
    period is warmer wrt 1961-90 than it should be.
    As for Tom's points
    His 4 is a good point.
    6 will just need some additional words. This might need a sentence
    saying how few stations these less good means relate to.
    7 is mostly secondary points that won't be that important. r-bar isn't
    calculated the way Tom thinks or maybe the paper implies. If you
    look back and re-read Jones et al. (1997) you'll see that r-bar is
    estimated from the earlier grid-box dataset. Probably just needs
    a few extra sentences.
    8. Is a reasonable point, but this will likely make the error bars
    smaller?
    9. I agree on this !
    10. If you compare with the old method merging this will show
    that this isn't that important. All that seems to be required is
    some more detailed explanation. The reason SST's appear
    better is that the autcorrelation from day-to-day and measurement-
    to-measurement is high (much higher than land).
    11. A model could also be used to demonstrate this. Better than
    NCEP/NCAR.
     Minor Points
    A. My copy had these odd citations. There is an @ sign after each reference.
    Probably came about when making the pdf?
    B. WWR volumes for the 1991-2000 were not included. We've just received
    these last week. Haven't had time to add them in. Harry will likely do this
    but not till early next year, when we have some more funds for him.
    D. Good point
    E. More text needed, with a reference back.  Maybe get David P to read through,
    if he hasn't already.
    F. We use anomalies
    G  Good point.
    H. I thought I'd caught all these.
    I. This is a good point. It would be useful to say that there
    isn't a master dataset that we all draw from. We just use all
    we can get.  This will answer N as well. I can write this. I have
    been in touch with Tom Peterson about this over the summer
    wrt Roger Pielke.
    J. Better explanation needed.
    K. These sd's differ though?
    P. Errors should be independent. Some rephrasing needed.
    Q. Agree that this needs to be clearer.
    S. More text needed.
    U. The recent periods are too short. May stations/countries
    haven't made the relevant simultaneous measurements.
     X will get answered in one of the main points.
    Z  comparison of the different weighting schemes will show this
    doesn't have much effect.
    EE One of these is the average station variance.
      Hope these are of some use.
    Cheers
    Phil

   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
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