date: Wed, 16 Jan 2008 11:13:44 +0800 from: "Zhongwei Yan" subject: Re: Draft paper on Chinese temperature trends to: "Phil Jones" 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" To: "Zhongwei Yan" Sent: Tuesday, January 15, 2008 10:38 PM Subject: Re: Draft paper on Chinese temperature trends > > Zhoingwei, > 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. > > Cheers > Phil > > > At 05:11 15/01/2008, you wrote: >>Hi, Phil, >> >>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. >> >>Zhongwei >> >>----- Original Message ----- >>From: "Phil Jones" >>To: "Yan Zhongwei" >>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 >> difference >> > 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.jones@uea.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.jones@uea.ac.uk > NR4 7TJ > UK > ----------------------------------------------------------------------------