Preliminar study of a possible ionospheric response to the QBO

MARTA ZOSSI DE ARTIGAS; NIEVES ORTIZ DE ADLER; ANA G. ELIAS

Concepcion

Congreso; 6ta COLAGE, Conferencia LatinoAmericana de Geofísica Espacial; 2001

ALAGE, Asociacion LatinoAmericana de Geofisica Espacial

Other authors found, with data from Okinawa, an association between the variance of the F2 layer critical frequency, foF2var, and the quasi-biennial oscillation, QBO. As a QBO index, the monthly mean zonal wind in the equatorial stratosphere at 40 mb, MMZW was used. To confirm this association monthly hourly foF2 data (between 12 and 18 LT), of March for the period 1957-1990 from four ionospheric stations were analyzed. Three are located between the northern and southern equatorial anomaly crest and the other is high latitude station. MMZW is the concatenation of values measured at different stations located between 3°S - 1°N and 172°W -104°E. The correlation coefficient, r, between foF2var and MMZW is 0.47 for Okinawa (26°N, 128°E), -0.16 for Huancayo (12°S, 75°W), 0.047 for Tucuman (27°S, 65°W) and 0.20 for Slough (51°N, 0.6°W). The low r of Huancayo, Tucuman and Slough is consistent with the spectrum analysis. In the case of the low-latitude stations, the most significant peak corresponds to a 3-4 year periodicity; there is also a less significant 11 year peak, and a non-significant 2-3 year periodicity peak (QBO period). For Slough, the only significant peak is the 11-year periodicty one. For Okinawa, the spectrum could not be estimated since the data series has gaps. We do not found a clear association between foF2var and the QBO. But the spectral analysis is pointing out a significant 3-4 year periodicity in foF2var at low-latitude stations, close to the QBO periodicity. This suggests the existence of a forcing mechanism, possibly associated to tropospheric processes and coupled to the QBO, which deserves to be studied.