Coordinated Analysis of the Zonal Mean Circulation and Semidiurnal Tide in the Mesosphere and Lower-Thermosphere Using Ground Based Radar and TIMED Observations

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

Palo, Scott E ATM-0000956 As part of this proposal both ground-based and TIDI observations from the TIMED satellite of the horizontal wind field will be used to estimate the spatial structure (latitude, longitude, and height) and temporal evolution of the semidiurnal tide, both migrating and non-migrating, on a monthly basis. The impetus for this effort is twofold. First, the semidiurnal tide has a significant influence on the structure of the MLT. However, little is understood about the underlying variability of the tide and the possible sources of this variability. One possible source of longitudinal variability is due to the non-migrating tidal components, which may result from zonally asymmetric heating in the lower-atmosphere, non-linear wave-wave interactions, or from in-situ sources in the MLT. To attack the problem of variability the longitudinal variability that results from the non-migrating tidal components must be separated from the source and propagation effects, such as the quasi-biennial oscillation, which can modify the structure of the migrating semidiurnal tide. To accomplish these research goals this proposal will utilize data from 21 ground-based meteor and MF radar systems. These data will be collected and analyzed in conjunction with the TIMED TIDI measurements. As a result of this proposal ground-based mean and tidal (24, 12, and 8 hour) estimates will be provided every 4 days from each station. These tidal estimates will be analyzed in conjunction with the TIDI measurements to provide an estimate of the zonal mean circulation, the migrating and non-migrating semidiurnal tides in the MLT on a monthly basis. An effort will be made to integrate ground-based measurements from stations not included herein but which are also funded as part of the TIMED/CEDAR program to extend these results to other latitudes.