from: Phil Jones <p.jonesatXYZxyz.ac.uk>
subject: Re: Urgent
to: "Rachel Warren" <r.warrenatXYZxyz.ac.uk>
Some changes interspersed into the text. I don't know why the change
was made in the first paragraph from 1850 to 1951. Change this back to 1850,
then all should be clear. I've made a couple of other changes. It would be
simpler just to remove the penultimate paragraph.
I'm away after today until April 26.
At 18:58 14/04/2008, Rachel Warren wrote:
We're finalising the ENV report IPCC section now. There's now a section on
your research, which I copy below for you to see. Simon Clegg has
come back with questions. He wants to know what your 'other sources'
of data for recent temperature records are, and he wants to know where
the data from 1850 onwards comes from if there were few stations back
then. Simon has clearly honed in on wanting a large amount of detail
on your work ...
Research in Climate Change
The Global Mean Surface Temperature Record
The temperature record produced by the School's Climatic Research Unit
has been an important contributor to Working Group I in the IPCC's
Assessment Reports. Many person years of effort have been needed to
evaluate the long-term homogeneity of the land station temperature
record, using monthly time series from over 3000 locations. These
have been collected by national meteorological services around the
world since 1850.
Not 1850 above !!!!
Also start sentence with Work - below.
Work was begun on the temperature record in 1978, using the
temperature record from land-based stations, and extended to cover the
marine sector in 1986 (and in co-operation with the Hadley Centre of
the U.K. Met Office from 1989).
Stations on land are at different elevations, and different countries
estimate average monthly temperatures using different methods and
formulae. In order to avoid biases, monthly average temperatures are
reduced to anomalies relative to the period with best coverage
(1961-90). Both the land and marine components of this temperature
record are then separately interpolated to a set of 5� x 5�
latitude/longitude grid boxes. The resultant gridded surface
temperature sets, known as HadCRUT3 (for Hadley Centre Climatic
Research Unit Temperature 3), and HadCRUT3v, extend from 1850 up to
present and are updated monthly and annually.
**paragraph on temperatures from 1850: what are the early data?**
Even temperatures in the modern 1961-1990 reference period are not
straightforward to evaluate: because many stations do not have
complete records, even for this period, several methods have been
developed to estimate 1961-90 averages from neighbouring records or
using other sources of data. OMIT THIS
I'd omit the above paragraph, as it doesn't add much. It just confuses.
Both the global surface temperature data sets, and the separate land
and marine grids, are used extensively by Working Group I for their
report The Physical Science Basis. The temperature record is a central
element of the chapter Observations: Surface and Atmospheric Climate
Change, but the data sets in their various forms are also used in the
chapters Historic overview of Climate Change Science, Paleoclimate,
Climate Model Evaluation and Understanding and Attributing Climate
Change), as well as by Working Group II.
On Tue, Mar 18, 2008 at 9:56 AM, Phil Jones <p.jonesatXYZxyz.ac.uk> wrote:
> Here's a few sentences. You can pick and choose which bits you want.
> Description of HadCRUT3(v) - the dataset names. CRU does the land and the
> Hadley Centre
> the ocean.
> Over land regions of the world over 3000 monthly station temperature time
> series are used. The basic monthly average temperature series are collected
> by the National Meteorological Services around the world. Coverage is denser
> over the more populated parts of the world, particularly, the United States,
> southern Canada, Europe and Japan. Coverage is sparsest over the interior of
> the South American and African continents and over the Antarctic. The number
> of available stations was small during the 1850s, but increases to over 3000
> stations during the period since 1951. For marine regions sea surface
> temperature (SST) measurements taken on board merchant and some naval
> vessels are used, supplemented by buoy data in recent decades. As the
> majority come from the voluntary observing fleet, coverage is reduced away
> from the main shipping lanes and is minimal over the Southern Oceans.
> CRU has spent many person years assessing the long-term homogeneity of the
> land station record and the Hadley Centre a similar time undertaking
> complementary assessments of the homogeneity of the marine data.
> Stations on land are at different elevations, and different countries
> estimate average monthly temperatures using different methods and formulae.
> To avoid biases that could result from these problems, monthly average
> temperatures are reduced to anomalies from the period with best coverage
> (1961-90). For stations to be used, an estimate of the base period average
> must be calculated. Because many stations do not have complete records for
> the 1961-90 period several methods have been developed to estimate 1961-90
> averages from neighbouring records or using other sources of data. Over the
> oceans, where observations are generally made from mobile platforms, it is
> impossible to assemble long series of actual temperatures for fixed points.
> However it is possible to interpolate historical data to create spatially
> complete reference climatologies (averages for 1961-90) so that individual
> observations can be compared with a local normal for the given day of the
> Both the component parts (land and marine) are separately interpolated (as
> anomalies from 1961-90) to the same 5� x 5� latitude/longitude grid boxes.
> The combined versions (HadCRUT3 and HadCRUT3v) take values from each
> component and weight the grid boxes according to their errors in estimation,
> so giving greater weight to the oceanic data as errors of estimate are
> generally smaller.
> The gridded surface temperature products (HadCRUT3 and HadCRUT3v) extend
> from 1850 up to present.
> Both HadCRUT3/HadCRUT3v and the separate land and marine grids (CRUTEM3 and
> HadSST2) are used extensively within WG1 of AR4, principally within Chapter
> 3 on 'Observations: Atmospheric Surface nd Climate Change', but the datasets
> in their various forms are used in Chapter 1 (Historic overview of Climate
> Change Science), Chapter 6 (Paleoclimate), Chapter 8 (Climate Model
> Evaluation) and Chapter 9 (Understanding and Attributing Climate Change), as
> well as in WG2.
> At 19:33 17/03/2008, Rachel Warren wrote:
> Hi Phil
> I went to see Simon Clegg - and ufnortunately need to trouble you
> again - sorry.
> Simon Clegg has emphasised that there really needs to be a section on
> the CRU temp record
> in the IPCC ENV research section in the ENV report. This means a
> paragraph on how the CRU temp record
> is put together and where it is used in IPCC. Simon insists that what
> is in the 2006/5 ENV report
> doesn't explain HOW the temp record is put together which is what he
> wants ....ie where data
> is collected from, how collated, what did CRU actually do, for how long etc
> Can you help? I'm going to be VERY unpopular if I don't hand this in
> complete on Wednesday so
> please can you send me something tomorrow?
> Dr Rachel Warren
> Senior Research Fellow
> Tyndall Centre
> Zuckermann Institute
> University of East Anglia
> Norwich NR4 7TJ
> Telephone 01603 593912
> Fax 01603 593901
> E-mail r.warrenatXYZxyz.ac.uk
> 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.jonesatXYZxyz.ac.uk
> NR4 7TJ
Dr Rachel Warren
Senior Research Fellow
University of East Anglia
Norwich NR4 7TJ
Telephone 01603 593912
Fax 01603 593901
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.jonesatXYZxyz.ac.uk