The GEMMA Crustal Model: Validation and Data Distribution
Negretti, Marco1; Reguzzoni, Mirko2; Sampietro, Daniele3
1Politecnico di Milano, Polo Territoriale di Como, ITALY; 2DICA, Politecnico di Milano, ITALY; 3GReD s.r.l., ITALY

The GEMMA project (GOCE Exploitation for Moho Modeling and Application), funded by ESA-STSE and ASI, is a new crustal model constrained by GOCE gravity field observations. This model has a resolution of 0.5°x0.5° and it is composed of seven layers describing geometry and density of oceans, ice sheets, upper, medium and lower sediments, crystalline crust and upper mantle. Apart from GOCE data other external information, namely ETOPO1 and recent global models of sediments and upper mantle density, has been used. Moreover the crystalline crust has been subdivided into geological provinces having their own density variation with depth. In the present work the GEMMA model is validated against local seismic profiles and other models at global and regional scale, showing a good consistency where validation data are reliable.

Apart from that the development of a WPS (Web Processing Service) for the distribution of the GEMMA model is also presented. The service gives the possibility to download, interpolate and display the whole crustal model, providing for each layer the depth of its upper and lower boundary, its density as well as its gravitational effect in terms of second radial derivative of the gravitational potential at GOCE altitude.

The WPS is developed according to standards defined by OGC (Open Geospatial Consortium) and it is implemented with free and open source software, namely GRASS GIS for data processing and pyWPS for the WPS interface, enabling everybody to directly access the code and improve it. The output products are delivered in the most widely used formats, like ASCII or GeoTIFF, that can be later on imported in many GIS (Geographical Information Systems). In this sense, WCS, WMS and WFS standard protocols have been implemented too.