A comparison of PMSE and other ground-based observations during the NLC-91 campaign

Abstract

During the period July–August 1991, observations were made of Polar Mesospheric Summer Echoes (PMSE) at 46.9 MHz and 224 MHz by the CUPRI and EISCAT radars, respectively, at two sites in northern Scandinavia. Those observations are compared here with observations of noctilucent clouds, 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 MHz, there is no evidence for a correlation before the beginning of August and only one event suggesting a possible correlation after the beginning 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 minimum in background wind strength in that time interval.