date: Mon, 30 Jul 2007 12:01:38 +0100
from: Nathan Gillett <n.gillett@uea.ac.uk>
subject: Re: Revised version of Nature paper
to:  peter.thorne@metoffice.gov.uk, Kate Willett <kmwillett@gmail.com>,  Phil Jones <p.jones@uea.ac.uk>

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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/

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