Dear Jim
My own experience in the 1960's and 1970's with Bellani radiometers were
that they wererather finicky and needed individual calibration. As far as
net radiometers go, the Funk tyoe (CSIRO) are pretty good, but need daily
supervision and something to scare off the birds. Some enterprising fellows
even put a circular wire on the same plane as the element around it, but far
enough so that the birds couldn't peck the spheres and they made it slack so
that the wire would give way and not supply a decent perch for the birds.
Louis du Pisani
-----Original Message-----
From: James Hansen <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Tuesday, September 12, 2000 8:35 PM
Subject: solar radiation data conversion


>Dear Colleagues,
>
>I need some help or literature on solar radiation instrumentation.  In
>particular, I need to convert daily irradiance measurements from a
>spherical (Bellani) net radiometer to global irradiance normal to a
>horizontal surface for crop simulation applications in Southern India.
>Intuitively, the response to diurnal and seasonal changes in solar
>angles will clearly be different between a spherical and a flat sensor.
>I assume that someone has worked out and validated an algorithm for
>converting between the two sensor shapes.  I will be grateful for your
>help.
>
>Regards,
>--
>Dr. James W. Hansen
>Associate Research Scientist - Agricultural Systems
>International Research Institute for Climate Prediction
>P.O. Box 1000
>Palisades, NY 10964-8000
>USA
>
>845-680-4410 (voice)
>845-680-4864 (fax)
>
>Please note that the IRI area code 914 is changing to 845. If you
>experience difficulty with 845, 914 will work through 31 December 2000.
>