Maps in real time

Last update: Aug. 2017

 

  Annual subscription to 15 min Global Horizontal Irradiation bitmap Maps in Wh/m² and in TIFF format delivered in real time (h-15 min) on a given area, during daylight time from 3:00 TU to 20:45 UT - FOR PAY prices on demand

  • Operational since March 2011
  • Spatial resolution and project: Meteosat Second Generation
  • Delivery: Wget type command on the SoDa servers. The Customer is identified through a login and password. A mirror backup server is available to increase the reliability of the service.
  • UV in real time: please note that we also provide UV maps in real time.

 

In practice

Inputs:

The Customer communicates the rectangular box over the area cover by the service.

Outputs:

To limit the load on the service, the GHI values are divided by a factor of 1.2 to be stored in 8 bit TIFF format, leading to the approximate precision of 1 watt.

It is also possible to GHI maps with a 10^-2 precision in 16 bit TIFF images.

Archive: please note that the Hc3v4-15mapGHI maps are conserved for the last 4 weeks.

Methodology

The Hc3v4-15mapGHI includes the post-processing layers that are available in the time series HC3v4. Here they are:

  1. Each pixel is re-interpolated in time at an exact 15 min UTC
  2. All pixels where sun elevation is below 2 degrees are interpolated
  3. Altitude correction (using SRTM Altitude database)
  4. Kc-max correction
  5. Bias correction

1. Each pixel is re-interpolated in time at an exact 15 min UTC

To be able to apply the re-interpolation, this step implies to already have the next slot. Let's take as example Germany maps today at 10:15.

HC15mapGHI creates a new map [server]/germany/germany_irr_1504221000.tif. It contains GHI irradiation extracted from the sole 1504221000 MSG slot, i.e. irradiation at approximately 10:11 UT for Germany.

Hc3v4-15mapGHI generates 2 maps:

  • [server]/germany-hc3v4/germany_irr_1504221000.tif contains GHI irradiation from 09:45 to 10:00 UT. This map is final.
  • [server]/germany-hc3v4/germany_irr_1504221015.tif contains GHI irradiation from 10:00 to 10:15 UT. This map is a 4 minutes forecast (for Germany) and will be updated 15 minutes later.

2. All pixels where sun elevation is below 2 degrees are interpolated

When the sun elevation is below 2 degrees, the previous service without post-processing layers (HC15mapGHI) was generating no data (pixel = 254). In the new service HC3v4-15mapGHI, the irradiation values are interpolated using an interpolation based on the persistance of the clearness index Kc (GHI/GHI_clearsky.

NB: this remark can be generalized for every missing MSG slot. The previous service without post-processing layers was generating no map for Germany, whereas the new service provides an interpolated maps based on Kc persistance.

3. 4. 5. Altitude, Kc_max and bias corrections

Altitude correction and Kc-max correction are bug fixes for altitude and albedo errors.

Bias correction is a global calibration of hc3v4 w.r.t. BSRN stations.