Helioclim-3 Real Time and Forecast - USAGE

Last update: Jul. 2017 Back to Web service >>

    Introduction - Inputs - Outputs

Introduction

This service provides HelioClim-3 version 4 radiation values estimated from satellite imagery for today and tomorrow. The Web interface is available for free, and the automatic access requires that you subscribe an annual subscription. Please    to receive a quotation.

Please note that this interface addresses two different services:

Data for today: real time and persistence model

As soon as a new Meteosat image is available every 15 min, the HelioClim-3 database is updated in real time. To receive a time series covering the whole current day, we decided to complete the time series by applying a persistence model. Please find more information about:

Data for tomorrow: similarity forecast model

This method explores the HelioClim-3 database to find for similar meteorological events in the past in order to make an estimation of the next day irradiation values. Please find more information about:

Inputs

  • HelioClim-3 versions: forecast is available for version 4 only.
  • Add Meteo Data: include (or not) meteo data More information on meteo data
  • Forecast Version: two options are available: "Persistence Forecast" (current day only) or "Similarity Forecast" (for day+1).
    NB: when "Similarity Forecast" is selected and the dates cover today and tomorrow, the service uses the Persistence model to provide the irradiation values for the current day and the similarity forecast model to cover tomorrow.
  • Latitude and longitude: enter the values in decimal degrees (we advise 3 or 4 digits after comma), or directly click on the map to select your point, or you can also use the "Search Address" tool on the top of the map.
  • Altitude: enter the altitude, or let us use our default high resolution elevation database SRTM (spatial resolution 90 m, uncertainty 10 m) by letting the default "Automatic" value.
  • Start date and End date: format yyyy-mm-dd.
  • Time step: "1 min", "5 min", "10 min", "15 min", "30 min", "hour", or "day".
  • Time reference: "UT" or "TST". More information on time references
  • Compute relief shadows: take into account (or not) the shadowing effect due to the far horizon.
  • Plane mode: "Horizontal Plane", "Fixed tilted plane", "2D Sun Tracking (DNI)", "1D Sun Tracking (North-South axis)", "1D Sun Tracking (East-West axis)", "1D Sun Tracking (Tilt tracking)", "1D Sun Tracking (Azimuth tracking)". Fore more details on how to set the tilt, azimuth and albedo parameters, please take a look to the plane mode table available below.
    If you need more information on the radiation components you need, please refer to the illustrations about plane orientations and radiation components. Please check also the azimuth convention adopted by SoDa
  • Output format: Classic CSV Format or Unified CSV Format More information on outputs
 

Meteo data

Meteo data can be retrieved. GFS (NCEP) is the meteo provider.

Note: When meteo data are retrieved, the new Unified CSV Format is automatically selected.

Top of page

Plane mode               

(More information on plane orientations and radiation components)  

         Plane mode Tilt (degrees) Azimuth (degrees) Albedo Animations
June 21st Dec. 21st
Horizontal Plane 0 NA NA See animated GIF See animated GIF
Fixed tilted plane <user setting> <user setting> <user setting> See animated GIF See animated GIF
2D Sun Tracking (DNI) Sun Tracking Sun Tracking <user setting> See animated GIF See animated GIF
1D Sun Tracking (North-South axis) Sun Tracking 90° or 270° <user setting> See animated GIF See animated GIF
1D Sun Tracking (East-West axis) Sun Tracking 0° or 180° <user setting> See animated GIF See animated GIF
1D Sun Tracking (Tilt tracking) Sun Tracking <user setting> <user setting> See animated GIF See animated GIF
1D Sun Tracking (Azimuth tracking) <user setting> Sun Tracking <user setting> See animated GIF See animated GIF

Top of page

Azimuth convention adopted by SoDa

Firstly, the azimuth convention is:

   Azimuth (degrees) Orientation
North
90° East
180° South
270° West
    

So orientation checking is :

  • A tilted plane is north oriented if azimuth < 90° or azimuth > 270°
  • A tilted plane is south oriented if azimuth > 90° and azimuth < 270°

NB: A plane which is not facing the sun might either be a human error, or may also be due to infrastructure or environmental needs (e.g. part of the rooftop north oriented).

Top of page

Outputs

The output format for the HelioClim-3 files is CSV (common separated values). When pushing the "process" button, wait a while and right-click on the appeared link to retrieve your file.

Output format can be:

  • Classic CSV (common separated values) Format: the historical SoDa format which changes according to the time step.
  • Unified CSV Format: a new format, simpler, and that Excel can read seamlessly.
    The differences are :
    • field separator: fixed to ";" 
    • date: defined in one column for YYYY/MM/DD
    • hour: expressed for human reading (no more as decimal)
    • format is time step independent

Note: When meteo data are retrieved, the new Unified CSV Format is automatically selected.

Please pay attention that you don't receive the same columns if you select horizontal plane or if you select any other orientation. The description of the columns is described on this page by selecting the adequate service in terms of time step and plane orientation.

Other characteristics:

  • Missing data: -999
  • The hypothesis of integration is "end of interval": e.g. hourly data at 11:00 means data averaged over 10:00 to 11:00

Top of page