{'fraction_non_alphanumeric': 0.032744282744282746, 'fraction_numerical': 0.009355509355509356, 'mean_word_length': 5.130573248407643, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Seasonal and magnetic activity variations of ionospheric electric fields above the southern mid-latitude station, Bundoora, Australia

We investigate the seasonal, local solar time, and geomagnetic activity variations of the average Doppler ve- locity measured by an HF digital ionosonde deployed at Bun- doora, Australia (145.1 E, 37.7 S, geographic; 49 S mag- netic). The Doppler velocities were heavily averaged to sup- press the short-term effects (<3 hours) of atmospheric grav- ity waves, and thereby obtain the diurnal variations attributed to the tidally-driven ionospheric dynamo and electric fields generated by magnetic disturbances. The observed seasonal variations in Doppler velocity were probably controlled by variations in the lower thermospheric winds and ionospheric conductivity above Bundoora and in the magnetically conju- gate location. The diurnal variations of the meridional (field- perpendicular) drifts and their perturbations exhibited a com- plex structure, and were generally smaller than the variations in the zonal drifts. The latter were basically strongly west- ward during the evening to early morning, and weakly east- ward during the late morning to just past noon. The zonal perturbations were strongly enhanced by increasing geomag- netic activity, and closely resembled the perturbation drifts measured by the incoherent scatter radar (ISR) at Millstone Hill (71.5 W, 42.6 N; 57 N). There was also some re- semblance between the diurnal variations in the meridional drifts. Overall, the comparisons suggest that with sufficient averaging, Doppler velocities measured with digital ionoson- des at mid-latitudes correspond to true ion motions driven by ionospheric electric fields. This is a useful result because apart from the ISRs located in the American-European sec- tor, there are no ground-based instruments capable of mea- suring electric fields in the mid-latitude ionosphere.