Mostrar el registro sencillo del ítem Meriwether, J. Faivre, M. Fesen, C. Sherwood, P. Veliz, Oscar 2018-07-18T16:44:53Z 2018-07-18T16:44:53Z 2008-03-26
dc.identifier.citation Meriwether, J., Faivre, M., Fesen, C., Sherwood, P., & Veliz, O. (2008). New results on equatorial thermospheric winds and the midnight temperature maximum.==$Annales Geophysicae, 26$==(3), 447-466. es_ES
dc.identifier.govdoc index-oti2018
dc.description.abstract Optical observations of thermospheric winds and temperatures determined with high resolution measurements of Doppler shifts and Doppler widths of the OI 630-nm equatorial nightglow emission have been made with improved accuracy at Arequipa, Peru (16.4° S, 71.4° W) with an imaging Fabry-Perot interferometer. An observing procedure previously used at Arecibo Observatory was applied to achieve increased spatial and temporal sampling of the thermospheric wind and temperature with the selection of eight azimuthal directions, equally spaced from 0 to 360°, at a zenith angle of 60°. By assuming the equivalence of longitude and local time, the data obtained using this technique is analyzed to determine the mean neutral wind speeds and mean horizontal gradients of the wind field in the zonal and meridional directions. The new temperature measurements obtained with the improved instrumental accuracy clearly show the midnight temperature maximum (MTM) peak with amplitudes of 25 to 200 K in all directions observed for most nights. The horizontal wind field maps calculated from the mean winds and gradients show the MTM peak is always preceded by an equatorward wind surge lasting 1–2 h. The results also show for winter events a meridional wind abatement seen after the MTM peak. On one occasion, near the September equinox, a reversal was observed during the poleward transit of the MTM over Arequipa. Analysis inferring vertical winds from the observed convergence yielded inconsistent results, calling into question the validity of this calculation for the MTM structure at equatorial latitudes during solar minimum. Comparison of the observations with the predictions of the NCAR general circulation model indicates that the model fails to reproduce the observed amplitude by a factor of 5 or more. This is attributed in part to the lack of adequate spatial resolution in the model as the MTM phenomenon takes place within a scale of 300–500 km and ~45 min in local time. The model shortcoming is also attributed in part to the need for the model to include a hydrodynamical mechanism to describe the merging of the zonal wind with the meridional tidal winds that converge onto the geographical equator. Finally, a conclusion of this work is that the MTM compressional heating takes place along the perimeter of the pressure bulge rather than within the bulge, an issue previously not appreciated. es_ES
dc.format application/pdf es_ES
dc.language.iso eng es_ES
dc.publisher European Geosciences Union (EGU) es_ES
dc.relation.ispartof urn:issn:0992-7689
dc.rights info:eu-repo/semantics/openAccess es_ES
dc.rights.uri es_ES
dc.subject Thermospheric winds es_ES
dc.subject Doppler effect es_ES
dc.subject Interferometry es_ES
dc.subject Atmospheric temperature es_ES
dc.subject Thermosphere es_ES
dc.title New results on equatorial thermospheric winds and the midnight temperature maximum es_ES
dc.type info:eu-repo/semantics/article es_ES
dc.subject.ocde es_ES
dc.identifier.journal Annales Geophysicae es_ES
dc.description.peer-review Por pares es_ES
dc.identifier.doi es_ES




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