Solar Geometry 2 Info

Solar Geometry 2 - Web service Usage

  Inputs - Outputs - Automatic access

Introduction

Solar Geometry 2 (SG2) is the second generation of library for computing the relative position of the sun and the earth made by MINES ParisTech. Available worldwide, it provides Sun declination, Solar hour angle, Sun elevation, and Sun azimuth.

Valid over the time period 1980-2030, the algorithm is 20 times faster than the well-know SPA algorithm (Solar Position Algorithm), with an accuracy order of approx. 0.005°. The code is available both in C langage and in Matlab. More information on the MINES ParisTech OIE research lab website.

The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement no. 262892 (ENDORSE project).

Inputs

  • latitude (in [-90°; 90°]) and longitude (in [-180°; 180°]): in degrees, with at least 3 digits after comma
  • altitude (in meters. Automatic if empty): in meters. Set "elevation=-999" to let SoDa get the elevation from Nasa SRTM database
  • Start Date (from 1980): set the first day of the request, e.g. "2018-01-01"
  • End Date (up to 2030): set the end day of the request, e.g. "2018-12-31"
  • Time Step (in minutes. Range is [1,1440]): in minutes, this value ranges from "1" up to  "1440" for daily values
  • Output Format: Comma Separated Values (CSV)

NB: Default time reference is "UT".

Outputs

  • # JDUT: universal julian date (day)
  • # YYYY: year
  • # MM: month of the year
  • # DD: day of the month
  • # H: hour of the day (decimal hour)
  • # DOY: day of the year
  • # DELTA: topocentric declination (radian)
  • # OMEGA: topocentric hour angle (radian)
  • # GAMMA_S0: topocentric Sun elevation angle without refraction correction (radian)
  • # ALPHA_S: topocentric Sun azimuth angle Eastward from North (radian)
  • # R: Sun-Earth Radius (ua)

Tip: The omega angle is not forced between -pi and pi. To do it, you may use
    omega= omega - (ROUND(omega/(2*PI))*2*PI)
where ROUND is the usual rounding operator that gives you the nearest integer of a given value.

Automatic access

The automatic access to Solar Geometry 2 service is described at http://www.soda-pro.com/help/automatic-access/solar-geometry-2

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