Land-Surface Discharge Model (LSDM) Physics

Forced with atmospheric precipitation, evaporation and temperature data the Land Surface Discharge Model (LSDM) simulates globally the vertical and lateral water transport and storage on land surfaces. Physics and parametrization is based on the Hydrological Discharge Model (HDM) and the Simplified Land Surface Scheme (SLS; Hagemann und Dümenil, 1998, 2003). The hydrological model captures all major continental water mass transport processes (soil moisture, snow, rivers and lakes, runoff, drainage) relevant for the generation of hydrological Earth rotation excitation functions (Walter, 2008; Dill, 2009). In addition to the former serial combination HDM+SLS, the integrated LSDM model enables interactions between land surface and river routing in both directions. This allows the correct representation of swamps and temporally flooded regions including an enhanced estimation of local high evaporation areas. Further on, LSDM is optimized for the combination with ECMWF atmospheric forcing data and the ocean model OMCT to represent the global water cycle for geodetic purposes. An automatic version for the quasi real-time generation of hydrological angular momentum functions (HAM) and gravity field variations that was established in 2007 (Dill, 2008) is producing continuously updated time series of daily HAM.

References  

• Dill, R., Hydrological model LSDM for operational Earth rotation and gravity field variations. GFZ ScientificTechnical Report STR08/09, 2008.
• Dill, R., Hydrological induced Earth rotation variations from stand-alone and dynamically coupled simulations. Proceedings of LesJournées 2008 "Systèmes de Référence Spatio-Temporels", Dresden, in prep., 2009.
• Hagemann, S., Dümenil, L., Documentation for the Hydrological Discharge Model, Technical Report No. 17. Max Planck Institute for Meteorology, Hamburg, Germany, 42pp.,1998.
• Hagemann, S., Dümenil Gates, L., Improving a subgrid runoff parameterization scheme for climate models by the use of high resolution data derived from satellite observations. Clim. Dyn. 21, 349-359, 2003.
• Walter, C., Simulation hydrologischer Massenvariationen und deren Einfluss auf die Erdrotation,Ph.D.-thesis, 195pp., TU Dresden, Germany, 2008.