date: Mon, 30 Jul 2007 12:01:38 +0100 from: Nathan Gillett subject: Re: Revised version of Nature paper to: peter.thorne@metoffice.gov.uk, Kate Willett , Phil Jones Hi Peter, peter.thorne@metoffice.gov.uk wrote: > Nathan, > > this looks good to me. A few very minor points: > > 1. The references are still in need of a bit of attention. The three new > refs (a,b,c) in the main text need to be numbered. The Methods refs need > to be incremented up by three as a result. The SI refs need to > renumbered 1,2,3 etc rather than referring to the ref numbers in the > main section. according to the editor's guidelines in the review. > > I realise this - sorry not for mentioning in my email - I'll sort these out once the refs are finalised. > 2. In the text and the response to reviewers you mention d&a up to 30 > EOFs, but in SI Fig 3 you go up to 100 now. We need to resolve this in > both the main text and the response to reviewers. We actually do better > analyses than the current text and response to reviewers implies! > > In the main analysis we use a 30 EOF truncation. In the sensitivity test I show truncations from 3 to 100. However, I note in the caption that the results for a 30 EOF truncation are equivalent to those shown in figure 3. I now note in the main text that results are robust to wide variations in the truncation, so hopefully this is now reflected in the text. > 3. Reviewer 3 asked whether it was RH or q that was important for heat > stress. This is a tricky one to answer directly because it depends upon > the index being used. In the Met Office we use two approaches that are > broadly interchangable, one uses "q" the other RH: > > Heat Stress Model for WBGT (Wet Bulb Global temperature): > > WBGT= 0.7 Tewb + 0.2 Tbg + 0.1 Tdb > > Where > > Tewb = Tw +(0.19 SQRT(S)) -(0.0354 ES) +(0.12 Tdb) -(0.087 U) -1.3 > > Here Tewb is the exposed wet bulb temperature (C), Tbg is the black > globe temperature (C) (a thermometer exposed to sunlight), Tdb is the > screen dry bulb temperature (C), Tw is > the screen wet bulb temperature (C), S is the net solar radiation > (W/m2), Es is the sturation vapour pressure, and U is the 10m wind speed > (m/s). > > > Environmental Stress Index (ESI) as proxy for WBGT: > > ESI = 0.62 * T - 0.007 * RH +0.002 * SR + 0.0043 * (T * RH) - 0.078 / ( > 0.1 + SR ) > > T = ambient temperature > RH = Relative Humidity > SR = Solar short wave radiation > > The bottom line is that if the air is humid then it inhibits evaporation > of perspiration and therefore the ability of the human (animal) body to > maintain its core body temperature. > Thanks for this on the apparent temperature - see also my email to Phil. Cheers, Nathan > Hope this is helpful > > Peter > -- **************************************************************************** Dr. Nathan Gillett, Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK. Tel: +44 (0) 1603 593 647 Fax: +44 (0) 1603 507 784 Email: n.gillett@uea.ac.uk http://www.cru.uea.ac.uk/~nathan/ ****************************************************************************