A COMPARISON OF PMSE AND OTHER GROUND-BASED OBSERVATIONS DURING THE NLC-91 CAMPAIGN

During the period July-August 1991, observations were made of Polar Me sospheric Summer Echoes (PMSE) at 46.9 MHz and 224 MHz by the CUPRI an d EISCAT radars, respectively, at two sites in northern Scandinavia. T hose observations are compared here with observations of noctilucent c louds, energetic particle precipitation and magnetic disturbances. The appearance and morphology of PMSE are found to be closely correlated at the two frequencies and the two sites, 200 km apart. No correlation is found between PMSE and noctilucent clouds or magnetic disturbance. No correlation is found between energetic particle precipitation and the appearance of PMSE at 46.9 MHz for the whole time period. At 224 M Hz, there is no evidence for a correlation before the beginning of Aug ust and only one event suggesting a possible correlation after the beg inning of August. A minimum in occurrence frequency for PMSE is found between 16 and 21 UT (17-22 LST) which may be related to an expected m inimum in background wind strength in that time interval.