On the capability to derive mass estimates from high-low satellite-to-satellite tracking data

Poster (2013, December)

Recently it has been shown that it is possible to derive time-variable gravity signals from high-low satellite-to-satellite tracking (hl-SST) missions (Weigelt et al. 2013, JGR:Solid Earth, doi:10.1002 ... [more ▼]

Recently it has been shown that it is possible to derive time-variable gravity signals from high-low satellite-to-satellite tracking (hl-SST) missions (Weigelt et al. 2013, JGR:Solid Earth, doi:10.1002/jgrb.50283). Based on the GPS information only, we will present results derived from the dedicated gravity field missions CHAMP, GRACE and GOCE which allow us to determine mass estimates for various applications. Hydrologically induced mass changes on land cause the strongest mass variations in the gravity field and can be easily identified in the hl-SST data, especially in areas with strong signals such as the Amazon basin. Ice melt in Greenland can be derived from the data and mass estimates compare well to corresponding GRACE estimates. Also, loading time series based on these gravity field solutions agree well with GPS observations for various stations around the globe. We also discuss the limitations of the data, e.g. in detecting signals related to glacial isostatic adjustment or earthquake-induced gravity field changes. Overall, we will demonstrate that the quality of the GPS data is sufficient nowadays and with a proper processing strategy it is possible to derive reasonable mass estimates. As such, this type of observations may allow to bridge a possible gap between GRACE and its successor GRACE Follow-On scheduled for launch in 2017. [less ▲]

Hydrological mass changes inferred from high-low satellite-to-satellite tracking data

Scientific Conference (2013, April)

The technique of deriving time variable gravity (TVG) field observations from high-low satellite-to-satellite tracking (hl-SST) is beginning to establish itself as a valuable and supplementary source for ... [more ▼]

The technique of deriving time variable gravity (TVG) field observations from high-low satellite-to-satellite tracking (hl-SST) is beginning to establish itself as a valuable and supplementary source for the determination and description of long wavelength geophysical phenomena. Recent developments in data processing techniques have pushed the limits of the accuracy of these types of observations and now allows for realistic determinations of long-term trends and annual amplitudes of hydrological signals. We use CHAMP data and a dedicated signal processing to derive annual and inter-annual variations in the largest catchments of the Earth system, e.g. Amazon, Ob and Lena. Results are validated by computing the correlation of aggregated water storage changes from CHAMP (and GRACE) with the hydro-meteorological storage changes. High noise levels demand a stronger filtering, e.g. larger filtering radius (1000-1400km), than usually applied in case of GRACE. We therefore also investigate the effect of filtering on the consistency with the hydrological mass changes and estimate the signal to noise ratio and the spatial and temporal dependency of the noise. We will show that hl-SST observations are a viable source of information for TVG which can even serve as a reliable substitute in the event of the impending end of GRACE's active lifetime. [less ▲]