L. Fenoglio-Marc (1), R. Rietbroek (2), S. Grayek (3), T. aus der Beek (6), M. Becker (1), J. Kusche (2) , E. Stanev(4), L. Menzel (5)

(1) Institut für Physikalische Geodäsie, Technische Universität Darmstadt, Germany, (2) GeoForschungsZentrum Potsdam, Germany, (3) Institut für Chemie und Biologie des Meeres, Universität Oldenburg, Germany, (4) GKSS Institute for Coastal research Geesthacht, (5) Universität Heidelberg, (6) CESR Universität Kassel

The project STREMP aims at quantifying the interaction of several sources of mass variation in a complex and relatively small region, the Mediterranean-Black Sea region.

The general goals are:

1. Determination, analysis and separation of the different components of the mass storage, such as ocean transport,exchange between land and ocean in Southern Europe and the exchange between the Black Sea, the Mediterranean sea and the Atlantic Ocean.
2. Improved representation of ocean processes as a result of increasing synergy between newly available satellite data and oceanic and hydrologic modeling.
3. Full exploitation of altimetry and GRACE data to attain their resolution limits in space and time.
4. Exploitation of the upcoming GOCE geoid and estimation of the mean dynamic topography

Figure 1: Region of study

Results of Phase I (Goals 1-3, Partners 1-3)

In the first phase of the projects two composite time-series, the hydrology corrected GRACE derived time-variable mass change and the steric-corrected sea level change from altimeter observations, are regionally compared at seasonal and interannual scales over the interval 2002-2007. The leakage of mass change from land in the GRACE estimates of ocean mass change is accounted for by removing hydrologic models (Fenoglio et al., 2006, 2007). The leakage of the remaining land signal is largest in the smallest basin considered, the Black Sea.

The major results obtained are:

1. A promising validation of GRACE in Mediterranean Sea, with a very good agreement between the composite time-series (RMS difference 15 mm, correlation 0.83, difference in trend of 0.2 mm/yr for monthly time series) (Figure 2, top left))

 

2. A lower agreement between the composite time-series in the Black Sea, related to the big leakage of land hydrology and to the inaccuracy of the hydrological model used (RMS difference 40 mm and correlation of 0.53 for monthly time series) (Figure 2, top right)

Figure 2: Basin average of monthly seawater mass anomalies from filtered steric-corrected altimetry (circle) and from hydrology-corrected GRACE (triangle). The GIA correction is applied.

Planes for Phase II (Goals 1-4, Partners 1-4)

The integrated assessment is based on data and models of increased resolution. Some new aspects are:

1. Development of a regional version of the hydrology model WATERGAP at higher resolution (5’x5’)
2. Use of simulated and real GOCE data

List of Publications:

1. Fenoglio-Marc, L., J. Kusche, and M. Becker (2006), Mass variation in the Mediterranean Sea from GRACE and its validation by altimetry, steric and hydrologic fields, Geophys. Res. Lett., 33, L19606, doi:10.1029/2006GL026851
2. Fenoglio-Marc L., J. Kusche, M. Becker and I. Fukumori (2007). Comments on “On the steric and mass-induced contributions to the annual sea level variations in he Mediterranean Sea” by D. Garcia et al., J. of Geoph. Res., Vol. 112, C12018,doi:10.1029/2007JC004196
3. Fenoglio-Marc L., J. Kusche, M. Becker (2007). Estimation of mass variation and mean dynamic topography in the Mediterranean Sea from altimetry and GRACE/GOCE geoids, in 3rd GOCE Users Symposium Proceedings, SP-627, ESA Publications Division
4. Kusche, J (2007): Approximate decorrelation and non-isotropic smoothing of time-variable GRACE-type gravity fields, Journal of Geodesy, 81:733-749.
5. Kusche J, Schmidt R, Petrovic S, Rietbroek R (2009): Decorrelated GRACE time-variable gravity solutions for science by GFZ, and their validation using a hydrological model, Journal of Geodesy, (accepted Feb 2009)

More information from:

www.ipg.tu-darmstadt.de/institutphysgeod/ipgd_personal/fenoglio.de.jsp