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168 results on '"Amory-Mazaudier, C."'

33. On equatorial geophysics studies: a review on the IGRGEA results during the last decade

Author

Amory-Mazaudier, C., Kobea, A., Vila, P., Achy-Séka, A., Blanc, E., Boka, K., Bouvet, J., Cécile, J-F., Cohen, Y., Curto, J.-J., Dukhan, M., Doumouya, V., Fambitakoye, O., Farges, T., Goutelard, C., Guisso, E., Hanbaba, R., Houngninou, E., Kone, E., Lassudrie-Duchesne, P., Lathuillere, C., Leroux, Y., Menvielle, M., Obrou, E., Petitdidier, M., Ogunade, S.O., Onwumechili, C.A., Rees, D., Sambou, E., Sow, M., and Vassal, J.

Published
2005
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34. Influence of orographic and canopy conditions on friction velocities observed during frontal events usinng doppler sodar obervations

Author

Kotroni, V. and Amory-Mazaudier, C.

Subjects
Planetary boundary layer -- Research, Doppler effect -- Usage, Winds -- Research, Earth sciences
Abstract

An analysis of sodar friction velocities is presented. The analysis focuses on such velocities during frontal events over regions bounded by various orographic and canopy conditions to evaluate the impact of topography. It is shown that decrease in horizontal wind speed is conditioned by frontal passage in the surface layer. In addition, increases in friction velocity follow such frontal passage.

Published
1993

40. Solar quiet current response in the African sector due to a 2009 sudden stratospheric warming event

Author

Bolaji, O.S., Oyeyemi, E.O., Owolabi, O.P., Yamazaki, Yosuke, Rabiu, A.B., Okoh, D., Fujimoto, A., Amory-Mazaudier, C., Seemala, G.K., Yoshikawa, A., Onanuga, O.K., Bolaji, O.S., Oyeyemi, E.O., Owolabi, O.P., Yamazaki, Yosuke, Rabiu, A.B., Okoh, D., Fujimoto, A., Amory-Mazaudier, C., Seemala, G.K., Yoshikawa, A., and Onanuga, O.K.

Abstract

We present solar quiet (Sq) variation of the horizontal (H) magnetic field intensity deduced from Magnetic Data Acquisition System (MAGDAS) records over Africa during an unusual strong and prolonged 2009 sudden stratospheric warming (SSW) event. A reduction in the SqH magnitude that enveloped the geomagnetic latitudes between 21.13°N (Fayum FYM) in Egypt and 39.51°S (Durban DRB) in South Africa was observed, while the stratospheric polar temperature was increasing and got strengthened when the stratospheric temperature reached its maximum. Another novel feature associated with the hemispheric reduction is the reversal in the north-south asymmetry of the SqH, which is indicative of higher SqH magnitude in the Northern Hemisphere compared to the Southern Hemisphere during SSW peak phase. The reversal of the equatorial electrojet (EEJ) or the counter electrojet (CEJ) was observed after the polar stratospheric temperature reached its maximum. The effect of additional currents associated with CEJ was observed in the Southern Hemisphere at middle latitude. Similar changes were observed in the EEJ at the South America, Pacific Ocean, and Central Asia sectors. The effect of the SSW is largest in the South American sector and smallest in the Central Asian sector.

Published
2016

48. Equatorial electrojet as part of the global circuit : a case-study from the IEEY

Author

Kobea, A.T., Amory-Mazaudier, C., Do, J.M., Lühr, H., Houngninou, E., Vassal, Jacques, Blanc, E., and Curto, J.J.

Subjects
CHAMP MAGNETIQUE, ELECTROMAGNETISME, VARIATION TEMPORELLE, IONOSPHERE, Physics::Space Physics, VARIATION SPATIALE, GEOPHYSIQUE, Physics::Atmospheric and Oceanic Physics, Physics::Geophysics
Abstract

Geomagnetic storm-time variations often occur coherently at high latitude and the day-side dip equator where they affect the east ward Sq field. This paper presents an analysis of ground magnetic field and ionospheric electrodynamic data related to the geomagnetic storm which occurred on the 27 may 1993 during the international Equatorial Electrojet Year during (IEEY) experiment. This storm-signature analysis on the auttoral, mid-latitude and equatorial ground field, and the ionospheric electrodynamic data leads to the identification of a sensitive response of the equatorial electrojet (EEJ) to large scale-auttoral return current : this response consists in a change of the eastward electric field during the pre-sunrise hours (0400-0600 UT) coherently to the high-, mid-, and equatorial-latitude H decrease and the decrease and the disappearance of the EEJ irregularities between the time-interval 0800-0950 UT. Subsequent to the change in h'F during pre-sunrise hours, the observed foF2 increase revealed an enhancement of the equatorial ionization anomaly (EIA) caused by the high-latitude penetrating electric field. The strengthening of these irregaluraties attesting by the Doppler frequency increase track the H component at the equator which undergoes a rapid increase around 0800 UT. The DeltaH variations observed at the equator are the sum of the following components S (subR), DP, DR, DCF and DT. (Résumé d'auteur)

Published
1998

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