cc: Phil Jones date: Wed, 15 Apr 2009 16:08:54 +0100 from: Ian Harris subject: Re: CRU Radiation data. to: "Juckes, MN (Martin)" Hi Martin, I've tracked down a file of the same name here, it looks to have been generated by Mark New in January 1999. Mark is of course at Oxford now. Mark's 1999 paper suggests that the conventional Doorenbos-Pruit calculations were used to convert between sun hours and cloud cover. More helpfully, I've found an IDL program in Mark New's space, not a million miles from the data file. It looks like this: pro netrad,jday,rlat,albedo,t,sun,ed,rn ; ; calculates net radiation using equations in Shuttleworth (1993) ; ; rlat - latitude ; jday - Julian day ; t - temperature ; sun - sunshine hours (per day) ; ed - vapour pressure (mb) ; albedo ; ac,bc - parameters of cloudiness equation ; rn - net radiation (mm/day) ; ; local variable declarations as=0.25 & bs=0.5 & ae=0.34 & be=-0.14 & bolz=0.000000004903 ac=1.0 & bc=0.0 ; ; first get extraterrestrial solar radiation ; hlat=2.501-0.002361*t solar,jday,rlat,s0,smax s0mj=s0*hlat ; ; now calculate incoming short-wave radiation ; IF smax gt 0.0 THEN begin st=(as+bs*sun/smax)*s0mj ELSE st=0.0 ENDIF ; ; net short-wave radiation ; sn=st*(1.0-albedo) ; ; long-wave radiation ; IF(ed>-5.0)THEN edkpa=ed*0.1 emm=ae+be*sqrt(edkpa) ELSE emm=-0.02+0.261*(exp(-0.000777*t*t)) ENDIF sto=(as+bs)*s0mj IF(abs(sto)>0.0)THEN begin f=ac*(st/sto)+bc endif ELSE begin f=0.0 ENDelse rln=-1.0*f*emm*bolz*(t+273.2)^4 ; ; calculate net radiation ; rnmj=sn+rln IF(rnmj eq 0.0)THEN begin rn=0.0 endif ELSE begin rn=rnmj/hlat ; mm/day ENDelse END ; PRO netrad Hope that helps! Cheers Harry On 8 Apr 2009, at 12:28, P.Jones@uea.ac.uk wrote: > Hi Martin, > I'm in the US and get back on Good Friday. Harry is > off this week. We'll have a look the week after Easter. > > I'd suspect this file might be normals for 61-90 > which are calculated from cloudiness with a formula. > > If this is the case the formula should be in one of > the New et al papers in J. Climate in 1999 ro 2000. > > Cheers > Phil > >> Hello Ian, Phil, >> >> >> >> I have got a user query about some radiation data we have on the IPCC >> DDC. It is the file crad6190.zip available from this page: >> http://www.ipcc-data.org/obs/get_30yr_means.html. >> >> >> >> There is no reference to "rad" data on your high resolution page >> http://www.cru.uea.ac.uk/cru/data/hrg.htm -- do you know where >> crad6190.zip comes from? >> >> >> >> Sincerely, >> >> Martin Juckes >> >> >> -- >> >> Scanned by iCritical. >> > > Ian "Harry" Harris Climatic Research Unit School of Environmental Sciences University of East Anglia Norwich NR4 7TJ United Kingdom