1184 
The ECTN tasks are: 
• The collection of data at a number of worldwide receiving stations. 
• The generation of standard products. 
• The creation and the maintenance of a central archive and a catalogue at ESRIN. 
• The distribution of products to users. 
• The development of the needed algorithms and processing software. 
The ECTN is receiving and archiving the AVHRR data from 10 stations covering Europe and Africa as well 
South East Asia. The stations participating or having an agreement to contribute to the ECTN central archive in 
Frascati are the following: Tromsoe, Oberpfaffenhaffen, Scanzano, Cairo, Mas Pal an as, Niamey, Nairobi, La 
Reunion, Manila, Terranova and Dundee. A world map representing the station coverage is given in Figure 1. 
For most number of stations, the processing and archiving is performed locally using the ESA developed 
Standard-family HRPT Reprocessing Kernel (SHARK) software, (Pittelia and Bamford, 1989). Other stations 
send directly to ESRIN the HRPT raw data, which is then converted to SHARP format and archived at ESRIN. 
Since April 1992, HRPT and LAC data are exchanged with NASA/USGS to ensure that the full archive of the 
“Global Land 1 km AVHRR Data Set Project” is available at ESRIN (20 000 pass per project year, Buongiomo et 
al„ 1993). To complete this data set some of the ECTN station were asked to send to ESRIN HRPT data as well 
as the normal SHARP products. 
3 Overview of the Processing System 
SHARK is a hardware and software system that extracts AVHRR imagery from the raw HRPT data stream, 
processes it and writes the processed data in SHARP format, (SHARK’S Users’ Manual , 1993, SHARK 
Technical Reference Guide. 1993). SHARP (Standard Family HRPT Archive Request Product) is an archive and 
distribution format fa AVHRR and TO VS data. It conforms to the Landsat Technical Waking Group’s 
“Standard Family Tape Format”. The SHARK system fulfil the ECTN requirements providing the following 
functions: 
• HRPT data acquisition. 
• Display of acquired data and selection of scenes to process. 
• Generation of SHARP products and digital Quick Looks. 
• Generation of entries in the catalogue of all archived data. 
• On line quality control. 
• Archiving of products on optical disk. 
• Archive management and CCT/exabyte user product generation. 
The SHARK system is in demonstration during the symposium at die ESA stand. It includes the different steps in 
processing from HRPT up to SHARP Level 2A and 2B described hereafter. 
4 The Products 
All SHARP products consist of segments of AVHRR imagery that contain no fewer than 720 scan-lines and no 
more than 1440 scan-lines. These size limits correspond to 2 and 4 minutes tr ansmis sion time. The data is 
ordered with the northern-most scans first, irrespective of the direction in which the satellite was fly ing when the 
image was scanned. Figure 2 shows the products available now and in the near future.