Hobbies:Weather Stuff

I am very interested in the weather, mainly from the viewpoint of receiving images from weather satellites, but also collecting my own weather data and trying to interpret it. I have a weather station which measures most of the normal weather items on a continuous basis and these are logged to a file on the computer. The computer program produces an output on the screen showing what is going on. A sample of this is shown below. Note that this is not necessarily up to date, as I have not yet automated the transfer of the data from home to the web site.

Click here for a monthly weather summary.

Weather Satellite Image Reception

There are two types of weather satellite: those in geostationary orbit and those in polar orbit. The former orbit at about 35,000 km above the earth, and appear to stay motionless in the sky, so they see the same view of the world every day. Polar orbiters, in contrast, orbit at about 900 km altitude, over the poles, so their view of the earth is more restricted and changes all the time. The signal from the geostationary satellites that I receive is called WEFAX (WEather FAX), and that from the polar satellites APT (for automatic picture transmission). WEFAX images can be animated by the software to show the progress of weather systems over several days. Click here for a sample infra-red WEFAX image. Click here for a sample APT image, which shows both visible light and infra-red images side-by-side.

The receiving station can receive both signals simultaneously, but not process them. Normally, I receive WEFAX images from the European satellite Meteosat 7, located at 0 degrees longitude over the equator. When I wish to receive a polar orbiter such as NOAA 15 or 16, I have to manually set the system to do so, usually just before the predicted pass of the satellite.

Many people with this hobby suffer from interference when trying to receive the weather satellite signals, which are very weak. I had this problem severely when living in Canada and subsequently wrote an article on my experiences on how to identify the source of the interference. Click
here to see this article. Note that some of the images in this article may take a while to load. Happily, I rarely experience interference here in Plan de la Tour, although some is visible on the APT image mentioned above.

Since 2003, the European Meterological Satellite consortium (EUMETSAT) has put in place a much improved method of diffusing weather satellite imagery using a conventional TV satellite (Eurobird 9). This method, named EUMETCAST, broadcasts imagery from all the Eropean geo-stationary weather satellites as well as polar orbiters, together with images from the USA, Japan, China and others, giving a remarkably comprehensive view of the planet's weather, updated as fast as every 5 minutes. The service is intended for the use of national met agencies but the service is available as a paying one to commercial operations, and to bona-fide amateurs and for educational purposes. I have been included as an authorised reciepient of the data since its inception and am supplied by EUMETCAST with an encryption key to allow reception. My receiving station for this data employs conventional TV satellite receiving gear but runs 24 hours a day, allowing beautifully animated images of the weather to be available at want. As of 2016 the transmission of data has been changed from the standard TV format of DVB-S to the HD format of DVB-S2 which allows for much more data to be sent, as is required for new satellites. It was necessary to upgrade the receiving station to this stnadard, meaning a new receiver and a more powerful computer. Here is an image from the 5 minute transmissions:(Click here)