Frequently Asked Questions.
===========================


Q1. Why aren't the images in colour.

A. Colour vision is possible because we 'see' in the 3 primary colours -
   Red, Green and Blue. With information from these 3 bands of the 
   spectrum we build up our colour view of the world. Light in this region 
   of the spectrum is referred to as 'visible' light. Meteosat has only one 
   channel that senses in the visible, so it can only detect variations in 
   overall brightness - it is effectively colour blind. However to compensate
   for this Meteosat has another channel that senses in the infra-red region
   of the spectrum, this has the advantage that it can still operate at night.
   False-colour pictures of the Earth can be produced from these 2 channels
   using special techniques and any 'colour' pictures you see from Meteosat
   will have been produced by this process.

Q2. Where can I get UK / European synoptic charts by internet ?

A. Unfortunately forecast charts have commercial value and are not available
   freely anywhere on the internet.

Q3. Where have all the MPEG's gone ?

A. These have been removed due to coding problems. When they return we 
   should have some new formats and better resolution ones on offer.

Q4. Is the data public domain ?

A. No, all Meteosat data is copyright EUMETSAT. If you wish to use 
   Meteosat data for publications etc contact :- 

   For Users who wish to use the data within Europe, contact your 
   national representative. 

   For UK Users, contact :

	Enquiries Office,
	The Met Office
	London Road
	Bracknell
	Berks RG12 2SZ

	Tel : 01344 854455 
        Fax : 01344 856087

   For Use outside of Europe, contact EUMETSAT

	EUMETSAT
	Am Elfengrund 45
	D-64242 Darmstadt-Eberstadt
	Germany

	Tel : (+49 61 51) 9 50-0
	Fax : (+49 61 51) 9 50-1 25

Q5. Can I get pictures for some particular date in the past?

A. Images are only kept at this site for one week. The University of
   Bayreuth in Germany has been archiving our images for some time and they
   are available from

   gopher://gopher.uni-bayreuth.de:70/11/Service/Meteosat


Q6. What is the resolution of Meteosat?

A.  Meteosat has a resolution of 5km at the sub-satellite point ( i.e the
    point directly below the satellite ). For Meteosat 5 this is on the
    equator at the Greenwich Meridian. As we go further away from this 
    point the resolution decreases due to the increasingly oblique angle
    that the satellite is viewing at. A whole Earth image at this resolution
    is 2500 x 2500 pixels.
    
    For the visible channel there are 2 seperate sensors that can be
    interleaved to give a maximum 2.5 km resolution.  ( 5000 x 5000 for a
    whole disk ). Only the visible images of specific areas are at the
    full resolution of the satellite.

Q7. Are there more local sites where the images can be obtained?

A.  Yes, dozens we believe. However there is no comprehensive list, so if
    archive / mirror site managers would care to email me 
    ( meteosat@ed.ac.uk ) with the site name, I'll compile them into a 
    list.

Q8. Where can I get information about other satellite images or
    meteorological data available by Internet?

    A current copy of the FAQ for sci.geo.meteorology can be obtained by 
    anonymous FTP to rtfm.mit.edu, from the file weather/data/part1 in 
    the directory /pub/usenet/news.answers.  These files are updated every 
    two weeks.

Q9.  What part of the spectrum does Meteosat use?

     Meteosat senses in 3 spectral bands, generally referred to as the 
     Visible channel ( 0.5 - 0.9 um ) , the Infra-red channel (10.5 - 
     12.5 um ) and the Water Vapour channel ( 5.7 - 7.1 um ).
     At present Water Vapour images are not available in this archive.
     Meteosat radiometers are only 6 bit instruments, these images have 
     been contrast stretched to fill the whole 8 bit range.

Q10. How are these images produced at Edinburgh ?

     The setup we have here consists of a 2 metre dish on the roof
     pointing at Meteosat 5. A downlink from this connects into a 
     Primary Data Receiver made by the Electronics Department at Dundee 
     University, Scotland. This in turn sends data to a host PC by a
     fast IEEE-488 bus. In between slots, the PC copies the received 
     data to a Sun on our LAN by PC-NFS, where all the data processing 
     and production of ftp-able images is done. All the software is home
     grown.


Q11. Where can I send comments / suggestions about this service ?

     meteosat@ed.ac.uk