From	Phil Jones	Date	Tue Jan 15 14:28:18 2008
To	Kevin Trenberth
CC	David Parker, Thomas C Peterson, Reinhard Boehm, Susan Solomon, Adrian Simmons
Subject	Re: Draft paper on Chinese temperature trends
Kevin, Homogeneity only done on mean T. Lots of sites just measure this. A lot will measure max and min, but I haven't got the data. I also didn't want to get into max/min as what is relevant to urban-related warming in the global land series (or China) is the effects on mean T. I can't then look at max or min against a rural series. I would expect max to have changed less than min, but I can't really look at that. Also I don't want to confuse readers by saying there is an urban-related temp influence, but it is to a lower DTR. I guess I could refer to Vose et al (our Fig 3.11) which does show a decrease in DTR for 79-04 over China (mostly blues). I'll work on the text. Cheers Phil At 04:50 15/01/2008, Kevin Trenberth wrote: Phil I looked at the paper in more detail. It obviously needs a bit of polishing throughout. I have a couple of fairly major comments. The first is that you only deal with the mean temperature and nothing on the max and min temperatures. Are those available? It would be much more powerful if those could be included. The second is the special situation in China associated with urbanization and that is air pollution. You do not mention aerosols and their effects. We have some on that in AR4 that may be of value: refer to our chapter. In China, there has been so much increase in coal fired power and pollution (11 out of the top worst ten polluted cities in the world are in China, or something like that). So you do not see the sun for long periods of time. Presumably that greatly cuts down on the max temp but may also increase the min through a sort of greenhouse effect? Effects of urban runoff tend to warm and space heating also warms but should mainly affect the min. Pollution may not be in the inner city but concentrated more near the sites of industry and power stations; but also may not be that local owing to winds? Pollution may also change fog or smog conditions, and may also change drizzle and precip. Looking at other variables could help with whether the changes are local or linked to atmospheric circulation. The unique aspect of urbanization related to air pollution should make China different, but may not be easily untangled without max and min temps (and DTR). Anyway, given these aspects, you may want to at least assemble the expectations somewhere altogether and discuss max (day) vs night (min) effects? Hope this helps Kevin > >> Dear All, > I have mentioned to you all 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 know you're > all > very busy and I could have been doing something more useful, but it > hasn't > taken too long. > 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 > ---------------------------------------------------------------------------- ___________________ Kevin Trenberth Climate Analysis Section, NCAR PO Box 3000 Boulder CO 80307 ph 303 497 1318 [1]http://www.cgd.ucar.edu/cas/trenbert.html 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 ---------------------------------------------------------------------------- References 1. http://www.cgd.ucar.edu/cas/trenbert.html