From nobody Mon Mar 2 13:03:47 1998 Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!news-peer-east.sprintlink.net!news-peer.sprintlink.net!news.sprintlink.net!Sprint!cpk-news-hub1.bbnplanet.com!news.bbnplanet.com!europa.clark.net!128.158.254.10!news.msfc.nasa.gov!pecos.msfc.nasa.gov!not-for-mail From: Michael Dworetsky Newsgroups: sci.astro.research Subject: Re: Index of Refraction of Atmosphere Date: 2 Mar 1998 08:18:44 -0600 Organization: University College London Lines: 44 Sender: astres@pecos.msfc.nasa.gov Approved: astres@pecos.msfc.nasa.gov Distribution: world Message-ID: <6def44$kpc@pecos.msfc.nasa.gov> References: <6c1lqj$crh@pecos.msfc.nasa.gov> <6ci3cq$ff5@pecos.msfc.nasa.gov> <6d6m4p$jm9@pecos.msfc.nasa.gov> Reply-To: Michael Dworetsky NNTP-Posting-Host: pecos.msfc.nasa.gov X-Trace: news.msfc.nasa.gov 888848322 505 (none) 128.158.132.24 X-Complaints-To: abuse@news.msfc.nasa.gov Keywords: techniques X-Posting-Tool: modtool v2.0 Xref: newsfeed.cv.nrao.edu sci.astro.research:403 Rodney Blackall wrote: > > In article <6ci3cq$ff5@pecos.msfc.nasa.gov>, > Michael Dworetsky wrote: > > Stephenson Tucker wrote: > > > > > > I am looking for the index of refraction of the atmosphere based >>on temperature, pressure, relative humidity and wavelength. > > > If you can find it, this is very useful: > > > Tablitsi Refraktsii Pulkovskoii Observatorii 5th Edn (1985). With a > > nice preface in English. > > > Boris Garfinkel, Astronomical Refraction in a Polytropic Atmosphere, > > probably would give you what you want if you don't need extreme > > accuracy. Plenty on horizontal refraction. Astronomical Journal, >72, p 235, 1967. > > This information is critically important to the armed forces who need > to know this for predicting the behaviour of radar beams. As a first > step you could try asking the Defence Services division of the UK > Meteorological Office. I know they have access to great expertise in > this field but of course do not know how much they can reveal. > > -- Ron Stone published a recent article (PASP 108, 1051, 1996). He gives analytical formulas that (he claims) are good to a few mas even at 75 degrees zenith distance. Thanks to Bill Owen for pointing this one out. This is for optical wavelengths. The atmospheric propagation is not similar at centimetric wavelengths typical of radar. For the latter, the military may have declassified some data in more than one country, or there may be information in ordinary journals. I haven't looked but thanks for mentioning this. > Rodney Blackall (retired meteorologist) > London, ENGLAND -- Mike Dworetsky, Department of Physics & Astronomy, University College London Gower Street, London WC1E 6BT UK email: mmd@star.ucl.ac.uk From nobody Mon Mar 2 13:04:00 1998 Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!newsfeed.internetmci.com!128.158.254.10!news.msfc.nasa.gov!pecos.msfc.nasa.gov!not-for-mail From: Maren Purves Newsgroups: sci.astro.research Subject: Re: Index of Refraction of Atmosphere Date: 2 Mar 1998 08:20:22 -0600 Organization: Joint Astronomy Centre, Hilo, HI Lines: 77 Sender: astres@pecos.msfc.nasa.gov Approved: astres@pecos.msfc.nasa.gov Distribution: world Message-ID: <6def76$kq4@pecos.msfc.nasa.gov> References: <6c1lqj$crh@pecos.msfc.nasa.gov> <6ci3cq$ff5@pecos.msfc.nasa.gov> <6d6m4p$jm9@pecos.msfc.nasa.gov> Reply-To: Maren Purves NNTP-Posting-Host: pecos.msfc.nasa.gov X-Trace: news.msfc.nasa.gov 888848420 587 (none) 128.158.132.24 X-Complaints-To: abuse@news.msfc.nasa.gov Keywords: techniques X-Posting-Tool: modtool v2.0 Xref: newsfeed.cv.nrao.edu sci.astro.research:404 Rodney Blackall wrote: > In article <6ci3cq$ff5@pecos.msfc.nasa.gov>, > Michael Dworetsky wrote: > > Stephenson Tucker wrote: > > > > > > I am looking for the index of refraction of the atmosphere based=20 >>on temperature, pressure, relative humidity and wavelength.=9B1] = > > If you can find it, this is very useful: > > Tablitsi Refraktsii Pulkovskoii Observatorii 5th Edn (1985). With a > > nice preface in English. > > Boris Garfinkel, Astronomical Refraction in a Polytropic Atmosphere, > > probably would give you what you want if you don't need extreme > > accuracy. Plenty on horizontal refraction. Astronomical Journal, >= 72, p 235, 1967. > This information is critically important to the armed forces who need > to know this for predicting the behaviour of radar beams. As a first > step you could try asking the Defence Services division of the UK > Meteorological Office. I know they have access to great expertise in > this field but of course do not know how much they can reveal. There was a paper from JPL ... I can't find the reference at the moment, but here's the code: SUBROUTINE SBEND (PRESS, TEMP, HUMID, ZNITH, R) DIMENSION A(2), B(2), C(2), E(12), P(2), T(2), Z(2) P (1) =3D 760.0 T (1) =3D 273.0 Z (1) =3D 91.870 P(2) =3D PRESS *760./1013. T(2) =3D TEMP +273.0 Z(2) =3D ZNITH A(1) =3D 0.40816 A(2) =3D 112.30 B(1) =3D 0.12820 B(2) =3D 142.88 C(1) =3D 0.80000 C(2) =3D 99.344 E(1) =3D 46.625 E(2) =3D 45.375 E(3) =3D 4.1572 E(4) =3D 1.4468 E(5) =3D 0.25391 E(6) =3D 2.2716 E(7) =3D -1.3465 E(8) =3D -4.3877 E(9) =3D 3.1484 E(10) =3D 4.5201 E(11) =3D -1.8982 E(12) =3D 0.890000 W0 =3D 7100.0 W1 =3D 17.149 W2 =3D 4684.1 W3 =3D 38.450 D3 =3D 1+DELTA (Z,C,Z(2)) FP =3D (P(2)/P(1)) * (1-DELTA (P, A, Z(2))/D3) FT =3D (T(1)/T(2)) * (1-DELTA (T, B, Z(2))/D3) FW=3D 1+(W0* 0.01*HUMID* EXP ((W1*T(2)-W2) /(T(2)-W3))/ (T(2)*P(2))= ) U =3D (Z(2)-E(1))/E(2) X =3D E(11) DO 1 I=3D1,8 1 X=3D E(11-I) + U*X R=3D FT*FP*FW * (EXP(X/D3)-E(12)) RETURN I just found this post ... I did a comparison between the refraction corrections from several submm telescopes at some point. Let me know (preferably by email) if you're interested in the fortran code. Maren Purves, now at UKIRT (where refraction doesn't depend on humidity)