HR: 1330h
AN: G52C-0053    [PDF]
TI: Effect of Seasonal Mass Loading Signals on VLBI Crustal Displacement Measurements
AU: * MacMillan, D S
EM: dsm@leo.gsfc.nasa.gov
AF: NVI, Inc.,NASA Goddard Space Flight Center, Code 926, Greenbelt, MD 20771 United States
AU: Boy, J
EM: boy@bowie.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Code 926, Greenbelt, MD 20771 United States
AB: Observed VLBI site position variations contain significant contributions at annual and semiannual frequencies (2-8 mm for the vertical). We have determined the extent to which these observed site variations can be explained by mass loading signals. Specifically, we examined the effects of hydrologic (soil moisture and snow) loading [Milly and Shmakin, 2002], nontidal ocean loading [ECCO model], and atmospheric pressure loading [using NCEP reanalysis data]. We find that application of mass loading models reduces annual vertical amplitudes for 70% of the 36 most frequently observed sites by up to 2-3 mm. Baseline length repeatabilities are reduced for about 2/3 of the baselines between these sites. In addition, we have examined corrections for errors specific to the VLBI technique, troposphere delay mismodeling and antenna thermal deformation, which also have seasonal signatures. We have also compared GPS site annual amplitudes derived from site vertical position time series [Dong et al., 2002] with corresponding VLBI amplitudes for colocated sites.
DE: 1208 Crustal movements--intraplate (8110)
DE: 1219 Local gravity anomalies and crustal structure
DE: 1247 Terrestrial reference systems
DE: 1645 Solid Earth
SC: Geodesy [G]
MN: 2003 Fall Meeting