High frequency nutation from GRGS multitechnique combination
Résumé
The team Groupe de Recherche en G ́eod ́esie Spatiale (GRGS) has determined an experimental 12-hourly time series of the celestial pole offsets, based upon the simultaneous processing of VLBI and GPS observations over the year 2007 thanks to the package GINS-DYNAMO developed by CNES and GRGS. It allows us to obtain the high frequency part of the nutation, between 2 and 10 days, poorly determined by the routine VLBI processing. Absent in routine VLBI series, peaks of a few tens of microarcseconds appear around 7 days. This is possibly the effect of the normal mode Ψ 11 of the atmosphere (period of 1.2 day in the terrestrial frame).