Investigation of Polar Motion from Doppler Tracking of the NNSS (Navy Navigation Satellite System) during the MERIT Campaign
DEFENSE MAPPING AGENCY HYDROGRAPHIC/TOPOGRAPHIC CENTER WASHINGTON DC
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For more than a dozen years, Doppler tracking of the Navy Navigation Satellite System NNSS has demonstrated the ability to give solutions for polar motion as a byproduct of precise ephemerides generation. This paper reviews the polar motion estimation process at the Defense Mapping Agency from Doppler measurements of the NNSS and gives comparisons to polar motion series from newer observational techniques and to the Bureau International delHeure Circucular-D series. The different techniques are compared for the period of the MERIT Main Campaign. In addition to comparing results for the Nova and Oscar NNSS satellites, comparisons are done utilizing the WGS 84 and the NWL 9Z2 gravitational fields in the precise ephemerides generation process. Keywords MERITMonitor Earth Rotation and Intercompare Techniques. Author.