Satellite data is available from the geostationary satellites GOES-16/17, Meteosat-8/11 and Himawari-8. The spatial resolution varies between 1 and 3 kilometers at the equator below the satellite. Images are available every 10 respectively 15 minutes depending on the source.
Please note that only certain parameters such as cloud_type(_transparent):idx or specific channels can be useful if queried as non-image data. The other parameters are intended for visualization purposes and are only meaningful if combined with an appropriate colormap (using png_default does that for you), as the values correspond to a specific color.
Images
A global false color composite that uses data from visible and near-infrared wavelengths and is consistent across all the satellites can be queried with the parameter
sat_rgb:idx
As Meteosat-11 provides a high resolution scan for limited areas, we provide another composite where we integrate it to provide increased fidelity over Europe. It can be queried with the parameter
Infrared composites can be queried with the parameters
sat_vis_006:idx
sat_ir_008:idx
sat_ir_016:idx
For the following wavelengths the brightness temperature is provided directly. Brightness temperatures can also be queried in °C by replacing K with C.
sat_ir_039:K
sat_ir_062:K
sat_ir_104:K
The number indicates the wavelength in tenths of micrometers, e.g. sat_ir_039:idx corresponds to the channel with a central wavelength of 3.9 μm.
Over Europe, there are additional parameters available that provide more information on clouds as seen from space.
Cloud Types
By combining data from sensors at various wavelengths, it is possible to distinguish cloud types due to their differing temperature and constituents. Such an image can be queried with the two parameters
sat_cloud_type:idx
sat_cloud_type_transparent:idx
sat_cloud_type:idx: if cloud-free, the index differentiates between cloud-free land (0) and sea (1) as well as snow covered land (2) and snow/ice covered sea (3). The different cloud types are explained in the table below.
sat_cloud_type_transparent:idx: cloud-free areas are set to -666 instead of 0, 1, 2 and 3. Also unclassified clouds (14) are set to -666.
Index
Cloud Type
0
Cloudfree land
1
Cloudfree sea
2
Snow covered land
3
Snow/ice covered sea
4
Very low stratus
5
Low clouds
6
Mid level clouds
7
High opaque clouds
8
Very high opaque clouds
9
Very thin cirrus
10
Thin cirrus
11
Thick cirrus
12
Thin cirrus above mid/low clouds
13
Fractional/broken low clouds
14
Unclassified
For visualization purposes, these indices are mapped onto colors according to the following legend:
If you wish to query an image that is transparent wherever there are no clouds and emplaces the HRV image data wherever there are clouds, you can do so by means of the parameter
sat_cloud_layer:idx
Please note that since the image data stems from HRV, the clouds will be black wherever there is no sunlight, e.g. during the night.
A clever combination of satellite images at certain wavelengths into an RGB can highlight low clouds and fog as well as distinguish them from one another. Two such RGB composite images queried by the following parameters:
sat_day_fog:idx
sat_night_fog:idx
For the interpretation of sat_day_fog:idx images please refer to the PDF SEVIRI Dust RGB Quick Guide. As indicated by the title of the PDF, this is also helpful with tracking dust clouds.
A brief guide to reading the sat_night_fog:idx images can be found in the PDF Night Microphysics RGB Quick Guide, with a more detailed presentation containing a lot of examples located here. Please note that the composite is tuned for night time and the presence of sunlight has a significant impact on both the contrast and interpretation of the colors.
