摘要：Characteristics of the intraseasonal oscillations (ISO) in the mesosphere and lower thermosphere (MLT) are investigated using meteor radar wind observations from a South American, equatorial station, São João do Cariri (7.4°S, 36.5°W) during 2008.A prominent ISO signature is observed during January-May in the period band approximately 40 to 70 days in the MLT zonal wind.In the lower atmosphere, a dominant ISO is observed in the period band approximately 30 to 60 days in the outgoing longwave radiation (OLR) (a proxy for convection), total columnar water vapor (a proxy for tides), and zonal wind.Considerable high correlation of the ISO between the MLT and lower atmosphere indicates significant dynamical coupling between the lower and middle atmosphere during the observational period.The MLT-ISO shows conspicuous downward propagation of the peak amplitude indicating the role of the dissipating upward propagating waves for its generation.The amplitudes in the zonal wind of the dominant tidal components in the MLT exhibit conspicuous ISO modulation.The eastward propagating waves and tides are surmised to be responsible for communicating the ISO signature from the lower atmosphere to the MLT.The origin of the MLT-ISO is believed to take place in the lower troposphere, below 4 km.The MLT-ISO is believed to be the imprint of the lower atmospheric Madden-Julian oscillation which travels eastward from the Indian Ocean-western Pacific Ocean to the present location.
关键词：Intraseasonal oscillations ;Lower and middle atmosphere coupling ;Meteor radar observations
