AN OVERVIEW OF NLC-91 - A ROCKET RADAR STUDY OF THE POLAR SUMMER MESOSPHERE

In late July and early August of 1991, a major suborbital scientific c ampaign (NLC-91) involving scientists from eight countries was conduct ed at ESRANGE, Kiruna, Sweden and at Heiss Island, Russia. The purpose of the program was to investigate the chemical, dynamical, and electr odynamical properties of the polar summer mesosphere. Thirty one rocke t flights were coordinated with two coherent radar facilities, EISCAT and CUPRI, and with other ground-based observatories and facilities. T his permitted direct comparison between the in situ measurements and t hose obtained by remote sensing of the mesosphere via continuous groun d-based monitoring. The primary objectives of the campaign were to stu dy noctilucent clouds (NLCs) and polar mesospheric summer echoes (PMSE s), including their possible relationship to local aerosols and/or sma ll scale turbulence. This overview describes the scientific program, d iscusses the geophysical conditions during launch activities, and revi ews some of the preliminary results. More detailed results can be foun d in the papers which follow.