Dharam,

This is a simple Pascal routine that will do for conversion for you. Note:
This is modified for RSA. eg: DALEN represents the max sunshine hour for a
particular month. In this case RSA.

The function takes as input:
1: sunshine hours (of type extend or float in C) for a particular day, and
2: the Julian day count (of type integer)

It returns the solar radiation for the given day.

You will have to modify this however. I suppose you could use the latitude
to determine the maximum sunshine hours at any given location on earth. Such
an equation you will easily get of the internet.



function Radiation(sun: extended; daycnt : integer) : double;
const DALEN : array[0..13] of extended = (0.0, 13.8, 13.1, 12.3, 11.4, 10.7,
10.3, 10.5, 11.1, 11.9, 12.8, 13.6, 14.0, 14.0);

var
  Xo, SOLK, ALPHA, BETHA, DAYFRC, RFD, RFDM : extended;
  JDA, NMNTH : integer;

begin

  JDA := daycnt;

  Xo := ((JDA + 10.0) / 365.0) * 360.0;
  Xo := Xo * 0.01745;
  SOLK := 30.85 + 12.65 * cos(Xo);
  SOLK := SOLK * 1E+6;
  ALPHA := 0.21;
  BETHA := 0.71;
  NMNTH := round(daycnt / 30 + 1);
  DAYFRC := sun / DALEN[NMNTH];
  if (DAYFRC > 0.5) then
    begin
      ALPHA := 0.29;
      BETHA := 0.5;
    end;
  RFD := SOLK * (ALPHA + BETHA * DAYFRC);
  RFDM := RFD / (DALEN[NMNTH] * 3600.0*24);
  Result := RFDMKep;
end;




















----- Original Message -----
From: "Dr Dharam Singh Dabas" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, April 17, 2002 6:11 AM
Subject: How to convert bright sunshine hours to solar radiation.


> Dear friends,
>
> I have sunshine hours data. Can somebody suggest me the way, reference to
> the logic or some program/utility to convert the sunshine hours to solar
> radiation for simulation in DSSAT?
>
> Thanks in advance,
>
> Dharam S Dabas
> CCS HAU, Hisar
>