date: Wed, 16 Jan 2008 11:13:44 +0800
from: "Zhongwei Yan" <yzwatXYZxyz.ac.cn>
subject: Re: Draft paper on Chinese temperature trends
to: "Phil Jones" <p.jonesatXYZxyz.ac.uk>
OK, Phil. I got your points.
Actually, even for Beijing the 'urbanization' bias as infered from my recent study is also quite small comparing with the whole warming trend, 0.1 vs 0.6 C/dec for the last 3 decades. I have no problem with your conclusion in the paper.
Our early analysis (Yan et al 2001 AAS) applied a bias (~0.1C/dec, based on Portman 1993 without rural record comparison) for Beijing during 1961-97, superimposing upon a linear warming of 0.2C/dec. It's a bit bizarre that my current analysis based on updated data (1975-2006) and detailed rural-site comparisons resulted in an almost same estimate for the urbanization effect, while warming goes on with a much stronger rate.
Keep in touch. Cheers. Zhongwei
----- Original Message -----
From: "Phil Jones" <p.jonesatXYZxyz.ac.uk>
To: "Zhongwei Yan" <yzwatXYZxyz.ac.cn>
Sent: Tuesday, January 15, 2008 10:38 PM
Subject: Re: Draft paper on Chinese temperature trends
> You have missed the point of the paper - or you seem to from
> your statement
> that it doesn't agree with your Beijing results. Beijing is just
> one site !!! What
> I'm looking at is the effect for the large area - which is what I'm
> calling CHINA-LI.
> The whole point in commenting on the other papers (like Ren et al.) is that
> you can't extrapolate results from one or even a few sites.
> I know SST doesn't represent land, but it is the only series I can think
> of that can be guaranteed to be unaffected. Again this is just for China
> as a whole - and the whole SST area east of China. I couldn't get
> Qingxiang Li
> to say which sites were rural and which urban. A more detailed analysis
> would look at coastal land sites with coastal SST, but they would
> be much noisier.
> Also what matters is that my gridded series (CRUTEM3v for China) looks
> just like CHINA-LI.
> I know the reanalysis can't be purified before 1979, unless the
> assimilation scheme
> is told the real observations have higher priority. Without higher
> priority you can't
> over come the model bias.
> What could be happening in much of China is that nighttime temps
> are warming
> much more than daytime, so any urban effect is reducing the DTR, but only
> slightly affecting mean T.
> At 05:11 15/01/2008, you wrote:
>>Thanks for informing of the recent analysis. I noted in the paper
>>that the urbanization effect on the analysis of the average warming
>>trend over a large area such as China is negligible.
>>It is somehow not encouraging to my recent analysis of a detailed
>>comparison between Beijing and rural sites temperature series. The
>>Beijing station moved to a more-urban site in 1981 and back in 1997.
>>We carefully compared the records during the subperiods around these
>>years. The results tend to suggest a possibly urbanization-related
>>trend of about 0.1C/decade. This estimate is very similar to that by
>>Portman (1993), which we applied in Yan et al 2001 AAS. A paper is
>>being drafted. I'll check again the results and send to you for
>>comment a draft when completed.
>>For the large-area mean trend analysis, I'd agree with your results
>>but just provide some points helping discussion.
>>(1) The SST can hardly represent the land base climate trend, as
>>there are regional differences and the atmospheric circulation
>>adjustments to SST do not necessarily lead to the same sign trend
>>over the adjacent land area.
>>(2) If the basic observations are contaminated by urbanization, I
>>wonder if the re-analysis data can be purified.
>>Best wishes and later greetings for a happy new year.
>>----- Original Message -----
>>From: "Phil Jones" <p.jonesatXYZxyz.ac.uk>
>>To: "Yan Zhongwei" <yzwatXYZxyzl.tea.ac.cn>
>>Sent: Monday, January 14, 2008 10:33 PM
>>Subject: Draft paper on Chinese temperature trends
>> >> Dear Zhongwei,
>> > I have mentioned to you that I've been working on a paper on
>> > Chinese temperature trends. This partly started because of allegations
>> > about Jones et al. (1990). This shows, as expected, that these claims
>> > were groundless.
>> > Anyway - I'd appreciate if you could have a look at this
>> draft. I have
>> > spelt things out in some detail at times, but I'm expecting if it
>> > is published
>> > that it will get widely read and all the words dissected.
>> > I want to make sure I'm referring to most of the Chinese literature
>> > on urban related warming trends.
>> > The European examples are just a simple way to illustrate the
>> > between UHIs and urban-related warming trends, and an excuse to
>> > reference Luke Howard.
>> > 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.jonesatXYZxyz.ac.uk
>> > NR4 7TJ
>> > 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