Southern polar cap DPS and CADI ionosonde measurements: 1. Ionogram comparison Original Research Article

Digisonde Portable Sounder 4 (DPS-4) and Canadian Advanced Digital Ionosonde (CADI) digital ionosondes were operated concurrently at the polar cap station Casey (110.5°E, 66.3°S geographic, 81.0°S magnetic), Antarctica during 2000–2001. These two digital ionosondes employ different antenna arrays and digital signal processing techniques, yet nevertheless are closely related instruments. An interleaved operation schedule permitted continuous recording of ionograms. Both instruments have proved reliable in monitoring the ionosphere. This paper presents observations of background ionospheric irregularities in the E- and F-region polar cap ionosphere using these two different digital ionosondes. The comparison between DPS and CADI ionogram records enabled us to devise alternative operation modes for the CADI program at Casey. The DPS has since been relocated to the polar cusp station Davis (78.0°E, 68.6°S geographic, 74.6°S magnetic), Antarctica.