Interhemispheric Asymmetry in the Mesosphere and Lower Thermosphere Observed by SABER/TIMED
Abstract
In this paper we analyze nearly 15 years of satellite observations of temperature, airglow, and composition in the Mesosphere and Lower Thermosphere (MLT) to quantify their interhemispheric asymmetries ao one can provide quantitative links between observed asymmetries and the spatial and temporal variations of the gravity wave activity. Two processes are believed to be responsible for observed interhemispheric differences in the MLT. The first is the direct radiation effect from the eccentricity of the Earth orbit amd the other is the difference in gravity wave source distribution and filtering due to asymmetries in mean winds of the lower atmosphere. Both processes have been theoretically investigated to explain the observed asymmetry in some of the atmospheric parameters, but not self-consistently in all observed parameters together. In this paper we will show the asymmetry in the time-varying zonal-mean latitudinal structures of temperature, airglow emission rate, and composition observed by TIMED/SABER. We will quantify their interhemispheric asymmetries for different seasons under different solar activity conditions. In addition, temperature measurements will also be used to obtain temporal and spatial morphology of gravity wave potential energies. We will interpret the asymmetry in the observed fields and examine qualitatively their consistency with the two responsible processes, especially the one due to gravity wave filtering process. Our goal is to introduce and to share the spatial and temporal morphologies of all the observed fields to the modeling community so, together self-consistently, they be can be used to gain physical insights into the relative importance of various drivers responsible for the observed asymmetry, especially the role of gravity wave induced eddy drag and mixing, a critical, but least quantitatively understood process.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMSA13B..05Y
- Keywords:
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- 0355 Thermosphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 2437 Ionospheric dynamics;
- IONOSPHERE;
- 2494 Instruments and techniques;
- IONOSPHERE;
- 2794 Instruments and techniques;
- MAGNETOSPHERIC PHYSICS