cc: "Leslie Malone" <Malone_LatXYZxyzeway.wmo.ch>
date: Tue Oct 3 15:13:06 2000
from: Phil Jones <p.jonesatXYZxyz.ac.uk>
subject: RE: Draft spreads 2.8 and 2.9
to: "Peter Scholefield" <Scholefield_PatXYZxyzeway.wmo.ch>, <M.VoiceatXYZxyz.gov.au>
Peter and Mary,
I've been away and am trying to catch up on emails before I go away
again Oct 6-10. After Oct 11 I hope to be in CRU for much of the rest
of the year.
I've printed off 2.9. I did look at the text whilst in Geneva. At that
time I was suggesting graphics for many of the spreads in 1 and 2.
As for the text of 2.9 Bill's discussion of trends depends a lot
on the period (the 20th century). Your attachment marked 3 bits in dark
green. The problem with some of these relates to variability from winter
to winter, which is high in many of the mid-latitude regions that Bill
1) 20th century over Northern Europe. There has been little trend in winters
over this region during the 20th century because winters were mild in the
first 40 years of the century.
2) Central and Eastern Siberia. Data is sparse for these regions earlier
this century. What Bill has said here is defensible, but it would seem
best to remove this sentence, because it is very difficult to be
certain either way. The trends in N. China relate to the period since 1951.
Since 1951 winters in C and E Siberia have warmed, but they were
milder in the first part of the century as in parts of Europe.
3) Snowcover and Satellites. The text needs to say that areal snowcover
estimates from satellites have only been made since the early 1970s.
There is much variability in the estimates from year to year and only the
trends to lower areas are significant in spring. So say from 1971/2 onwards.
At 09:49 AM 9/27/00 +0100, Peter Scholefield wrote:
>Your concerns on 2.9 are valid. I can't dispute Bill's comment with information that we have here. We need to see the full century winter season trends which Phil probably has. I suggest that we get Phil to focus on and adjust as required the sentences about winter temperature trends over the 20th century. This bit of text needs some green highlighting which I have added in the version attached below. I will copy Phil on this message.
>Having spent most of my life in locations (Vancouver, Geneva and Lahr, Germany) that have average daily minimum temperatures near 0 C in January and a colder location like Toronto that has average daily maximum temperatures near 0 C in January, I fully appreciate what Bill is getting at and it is a clever (perhaps too clever) way to do it because he defines climatic zones based on the critical freezing point temperature of 0 C. Recognizing that this sublty might be missed, I did give some clarity to the fact that he was trying to delineate areas with mild to moderately cold winters, by giving expamples of regions outside this climatic "belt" as Bill refers to it.
>Would the following rewrite make it clearer:
>"Roughly speaking, major cities within the climatic zones delinated by those having average daily minimum temperatures near 0 C in January and those with slightly colder winters having average daily maximum temperatures near 0 C in January, are likely to experience wildly differing amounts of snow and ice from year to year due to fluctations in temperature around the freezing point."
>I did make a slight change in the attached version by replacing the "same figure" by 0 C to emphasize the importance of the freezing point.
>Mr. Peter Scholefield
>Chief, World Climate Data and Monitoring Programme Division
>World Meteorological Organization, Geneva, Switzerland
>Tel: (+4122) 730 8377, Fax: 730 8042, Home: 366 3712
>>>> "Mary E. Voice" <M.VoiceatXYZxyz.gov.au> 09/27/00 01:40am >>>
>Good day Peter
>I have managed to have a quick look at 2.8 and 2.9, both spreads. The
>winter storms spread looks pretty good to me. Maybe Pan Mao could provide
>an example from China.
>Regarding 2.9, cold winters and cool summers, I have some concerns. I
>assume that Phil Jones would have looked at this spread when he was in
>Geneva a few months back, so maybe I am completely wrong . Firstly with
>respect to the trends, I find it difficult to reconcile what is said here
>with what is said generally about global warming. We are saying here that
>there is very little change in winter temperatures over Europe, the USA and
>central and eastern Siberia (or even an opposite trend!!).
>Taking eastern Siberia first, I recall seeing a global map recently which
>showed that minimum temperatures over most of China had risen around four
>degrees over the century (i thought it was minimum winter temps). This is
>very dramatic and does not coincide at all with what is being said here
>about eastern Siberia. Surely something is wrong.
>Taking the more general case, one reads about fewer frosts in many parts of
>the world this century. This is certainly the case in Australia and is a
>winter and spring phenomenon. And I thought that minimum temperatures were
>rising in all seasons, although not uniformly across the seasons. It is hard
>to to reconcile these data with the words in spread 2.9.
>So I think what is being said here needs to be carefully checked. Maybe it
>is just a matter of a subtle shift in emphasis here and there, or more words
>of explanation, but at the moment I think we run the risk of confusing the
>I am afraid I do not understand the intent of the sentence beginning:
>"Roughly speaking, major cities in the.......
>What does "experience winter temperatures in January between an average
>minimum of around 0 to an average maximum of the same figure", mean? There
>are a couple of answers that I could think of. And anyway, I don't know how
>this relates to the next phrase, "more likely to experience wildly differing
>amounts of snow and ice from year to year". I can understand it for average
>maximums around 0, but can't get my head around the same concept for
>average minimums around 0, because in that case the maxima are likely to be
>8, 9 or 10? What do you think Bill is trying to say?
>Sorry, I don't have time today to look up the global maps of 20th-century
>change of temperatures which would help me with my first concern above. I
>will try to do this sometime in the next few days.
>Attachment Converted: "c:\eudora\attach\chapter 2 draft 2.9 27-9-00.doc"