IMPROVEMENT OF THE TRANSFORMATION BETWEEN ITRF AND DOPPLER-REALIZED WGS84

The WGS84 (World Geodetic System 1984) reference system is, originally , mathematically defined from the NSWC-9Z2 (Naval Surface Weapons Cent er - 9Z2) reference system. The WGS84 associated realization, called i n this paper WGS84-D, is a 1 meter consistency NNSS (US Navy Navigatio n Satellite System) Doppler realized reference frame. In contrast, the ITRF (IERS Terrestrial Reference Frame) is a I centimeter consistency reference frame realized through the most accurate techniques of Spac e Geodesy. This work intends to improve the transformation parameters between the WGS84-D and the ITRF through the use of both a NSWC-9Z2/Do ppler realization and an extension of the ITRF network. A strong linea r correlation was also modeled between the Doppler determined scale fa ctor and the mean smoothed sunspot number, due to uncompensated ionosp heric effects. This correction improved NSWC-9Z2 (i.e. WGS84) Doppler realization consistency. The uncertainty of adjusted transformation pa rameters between the ITRF and the WGS84-D is improved by a factor 2 ov er previous determinations.