Helmholtz Centre Potsdam
GFZ German Research Centre for Geosciences
Abstract (EDOC: 12430)
The variation in the sea level of the semi-closed Baltic Sea has been monitored in several complimentary ways. Now GRACE provides a method to directly measure the total mass variability in the Baltic. Using in situ and modelled Baltic data, we show that GRACE is able to recover the variation in the total water mass. We derive sea level surfaces from tide gauge data and estimate steric effects using hydrodynamic models as well as in situ salinity and temperature measurements for their verification. With its areal extent (~400 km x 1000 km) as well as fast temporal variations (hourly to monthly), the Baltic Sea provides a challenging test field for the temporal and spatial resolution of GRACE. We use both the standard monthly GRACE gravity field solutions and regional solutions and compare their capability to recover Baltic water mass variations. Due to spatial averaging, the GRACE mass estimates over the elongated area are contaminated by signals outside the region. The contribution of continental hydrology can be removed using water storage models to estimate mass variations on surrounding land areas. We discuss the processing steps required for the different GRACE solutions to improve the GRACE mass estimates for the Baltic, including mitigation of signal leakage as a result of spatial filtering. The capability of GRACE to recover internal mass redistributions in the Baltic is also investigated. Finally, we discuss the reduction of the Baltic contribution for studying land-uplift signal due to post-glacial rebound.
(2008): Improving GRACE mass estimates for the Baltic Sea and validation using in situ measurements.. AGU 2008 Fall Meeting. (San Francisco, USA 2008).