``Vetenskapsmannen är en byggmästare. Att samla vetenskapliga uppgifter kan jämföras med att samla stenar till ett hus; en hög med uppgifter är inte mer ``vetenskap'' än en hög stenar är ett hus. Obearbetade vetenskapliga resultat är bara en död stenhög''
``Wovon man nicht sprechen kann, darüber muà man schweigen''This chapter attempts to provide a summary of the scientific results obtained from the analysis of data from ALIS. It is important to stress that this can only be a brief review of published scientific results in order to demonstrate the scientific applicability of ALIS in particular, and of multi-station imaging in general. The reader is urged to read the original papers for more complete and detailed information about the scientific results summarised.
Interesting results often emerge from unexpected directions. HF pump-enhanced airglow was not mentioned among the scientific objectives in the early ALIS papers. However, this topic existed as an auxiliary scientific objective until 16 February 1999, when the first unambiguous observations of this phenomenon at high-latitudes were made. Since then it has been the main scientific objective of the ALIS measurements. Hence, a large portion of this chapter (Section 6.4) is therefore devoted to these observations.
It is essential for a proper interpretation of the data-sets to do coordinated observations involving as many independent measurement systems as possible. ALIS has participated in a number of coordinated campaigns involving instrumentation such as the tri-static European Incoherent SCATter radar (EISCAT), the EISCAT Heating facility in Tromsø, the American FAST, POLAR and MSX satellites, and the German lee-wave campaign studying polar stratospheric clouds etc.
The author's main role has been to supervise and make the observations with ALIS and supporting instruments, retrieve, calibrate and validate the datasets, as well as to assist with data-analysis and interpretation of the data-sets. Most ALIS data-analysis software, and in particular the software for triangulation and tomography-like analysis has been designed and written by Björn Gustavsson. He also performed most of the data-analysis. Many other coauthors (see the bibliography) contributed to the physical interpretations of the data-sets obtained from ALIS. This division of responsibilities appeared naturally in a small group with a large and technically complex project.