Abstract
Abstract. On the basis of MEM spectrum analysis, the main planetary scale fluctuations formed in the lower ionosphere are studied over a period of 3–25 days during the CRISTA campaign (October-November 1994). Three dominant period bands are found: 3–5, 6–8 and 15–23 (mainly 16–18) days. For 7–8 and 16–18 day fluctuations, propagation was eastward with wave numbers K = 3 and K = 1, respectively. The magnitude of planetary wave activity in the mid-latitudes of the Northern Hemisphere during the CRISTA campaign seems to be fairly consistent with the expected undisturbed normal/climatological state of the atmosphere at altitudes of 80–100 km.Key words. Ionosphere (ionosphere-atmosphere interactions) · Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)
Highlights
Planetary wave activity in the upper middle atmosphere at mid-latitudes has predominantly been studied in winter, partly as a comparison with summer conditions
The aim of this study is to look at planetary wave activity in October-November 1994 based on radio propagation data from the lower ionosphere (h = 80±100 km) collected during the international CRISTA campaign
The international CRISTA campaign was a large international campaign of rocket, balloon and ground-based measurements associated with the CRISTA (CRyogenic Infrared Spectrometers and Telescopes for the Atmosphere) and MAHRSI (Middle Atmosphere High Resolution Spectrometer Instrument) experiments launched by a US space shuttle
Summary
Planetary wave activity in the upper middle atmosphere at mid-latitudes has predominantly been studied in winter, partly as a comparison with summer conditions. The aim of this study is to look at planetary wave activity in October-November 1994 based on radio propagation data from the lower ionosphere (h = 80±100 km) collected during the international CRISTA campaign. It is continuation of our previous study made for the DYANA winter campaign (Pancheva et al, 1994), January-March 1990. Fluctuations of 10±11 days are observed only in some absorption data (analogous to fmin data of Irkutsk) They are the best developeductuation in the phase-height measurements (IPHA) at 162 kHz. The ®ltered 4- and 6-day waves in the day-time absorption measured at El Arenosillo and Panska Ves show very good coincidence.
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