Weather Glossary--Satellite Terms

          AVHRR - Advanced Very High Resolution Radiometer.  Imaging
          instrument onboard the NOAA polar orbiting satellites. 
          Produces infrared (IR) and visible images with a resolution
          of 1 km at the earth's surface.
          
          CONUS - CONtinental United States.

          DMSP - Defense Meteorological Satellite Program.  A series
          of low altitude, polar orbiting satellites operated by the
          Department of Defense.  Data is made available via the
          Shared Processing Network and archived at the National
          Geophysical Data Center, Boulder, CO.
          
          FTP - File Transfer Protocol.  Software used to transmit
          data files from one computer host to another.
          
          GIF - Graphical Information Format.  Most common image
          format used on Internet. Developed by Compuserve.  Main
          advantage is that GIF images occupy relatively little file
          space.  Uses an encoding method known as interlacing. 
          Successive passes (up to four) provide increasing clarity as
          an image is decoded.
          
          GOPHER - Type of communications session used to access
          weather text and graphics at many university Internet
          servers.  Developed at the University of Minnesota ("Golden
          Gophers").
          
          GOES - Geostationary Operational Environmental Satellite.  A
          U.S. satellite operated by NOAA.  Positioned in a nearly
          stationary orbit over the Equator at an altitude of about
          22,500 miles.
          
          GUI - Graphical User Interface.  Name applied to any type of
          software that uses buttons to browse through graphic
          information.
           
          Home Page - First page displayed at a web server or a user
          directory accessed via Internet. Similar to a table of
          contents to allow quick access to desired information.
          
          HRPT - High Resolution Picture Transmission.  High
          resolution imagery from the AVHRR on the NOAA satellites. 
          Produced in five channels with a resolution of 1km at nadir. 
          
          HTML - Hypertext Markup Language.  A multimedia document
          format on the Internet that links highlighted text to other
          text or graphic files.  Permits a user to quickly browse
          through information without concern for command syntax.
          
          http - Hypertext Transfer Protocol.  Software used to
          transmit multimedia data across the Internet.
          
          IR - Infrared.  Type of satellite image that shows
          earth-emitted radiance in various wavelengths.  Advantage is
          that it can be used to monitor weather and oceanographic
          conditions 24 hours a day.
          
          JPEG - Joint Photographic Expert Group.  Image format that
          uses data compression techniques to reduce the size of the
          image file.  Supports 8 or 24 bits-per-pixel.
          
          LAC - Local Area Coverage.  High resolution (1km) image data
          from AVHRR that is obtained over remote areas, saved via
          onboard data recorder, then later transmitted to a ground
          station. 
          
          Meteosat - Series of geostationary satellites operated by
          the European Space Agency.  Meteosat produces imagery in
          visible, longwave IR (10.5fm) and water vapor (6.5fm)
          channels.  Usually centered near 0xW Longitude.
          
          Mosaic - Web browsing software available from the National
          Center for Supercomputing Applications (NCSA). Can be
          obtained free via anonymous FTP from: NCSA.
          
          MPEG - Moving Picture Experts Group.  Image format used to
          display animated sequences (movies).  Requires considerable
          system memory to run (16Mb recommended).
          
          NESDIS - National Environmental Satellite Data, Information
          Service.  Government agency that operates the U.S. civilian
          weather satellites and provides the data to users.  Also
          operates the environemental data centers such as NGDC and
          the National Climatic Data Center (NCDC) in Asheville, NC.

          Netscape - Newer type of web browsing software.  One of
          benefits is that graphics can be viewed before all of the
          document load is complete.  Can be downloaded from:
          MCOM.
   
          NGDC - National Geophysical Data Center, Boulder, Colorado. 
          Provide imagery from DMSP satellites.
          
          NMC - National Meteorological Center, Washington, DC. 
          Source of many of the weather maps and numerical forecast
          model information available.  Soon to become NCEP (National
          Center for Environmental Prediction).
          
          NOAA - National Oceanographic and Atmospheric
          Administration. Refers to a series of low earth orbit
          satellites at an altitude of 530 miles.  Orbits are
          sun-synchronous such that they pass over a location at about
          the same local time each day. Operated by NOAA.
          
          OLS - Operational Line Scanner.  The imager that produces
          high resolution (0.5 to 2.7 km) visible and infrared imagery
          from DMSP satellites.
          
          PPP - Point-to-Point Protocol.  Communications interface
          used to obtain access to Internet.
          
          SAA - Satellite Active Archive.  Digital archive of
          satellite imagery from the NOAA polar orbiting series.  User
          can browse through sample images and order digital data
          online.
          
          SLIP - Serial Line Internet Protocol.  Another type of
          communications interface used to get on the Internet.
          
          SSM/I - Special Sensor Microwave Imager.  Instrument that
          produces microwave data from four frequencies (seven
          channels) on DMSP satellites.  
          
          TCP/IP - Transfer Control Protocol/Internet Protocol. 
          Standard format for data transmission on Internet.
          
          Telnet - Type of telecommunications session used for basic
          logon to a remote computer site.
          
          World Wide Web (or WWW, or the Web) - A network of computer
          hosts on Internet that allows easy access to graphical and
          alphanumeric information.

          (Published in _National Weather Association Newsletter_,
          August 1995, p. 3, 5 & 6)