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Analysis of temporal and spatial structures of soil moisture by integrating remote sensing and process based modelling

within the Transregional Collaborative Research Centre 32  

Project Staff:

Prof. Dr. Karl Schneider (Chair, Modelling & Remote Sensing)
PD Dr. Peter Fiener (Coordination, Modelling & Field Measurements)
Dipl.-Geogr. Wolfgang Korres (Field Measurements & Modelling Soil Hydrology)
Dipl.-Geogr. Christian Koyama  (Field Measurements & Radar Remote Sensing) 

Project period:

2007- 2010 during funding phase I of the

The Transregional Collaborative Research Centre 32 -
Pattern in Soil-Vegetation-Atmosphere Systems:
Monitoring, Modelling, and Data Assimilation

The Transregio 32 works on exchange processes between the soil, vegetation and the adjacent atmospheric boundary layer. The overall research goal is to yield improved numerical models for the prediction of water-, CO2- and energy-transfer by accounting for the patterns occurring at various scales. See also a short summary of the full project and the summaries of the sub-projects below. 

Project section:

C3: Analysis of temporal and spatial structures of soil moisture by integrating remote sensing and process based modelling

Understanding the temporal and spatial patterns of soil moisture is important for a range of applied tasks such as water and agricultural management, as well as research tasks such as understanding local impacts of large scale processes (e.g. climate change). The general goals of the proposed sub-project are to improve the understanding of the temporal and spatial patterns of soil moisture at different spatial scales, to diagnose the driving parameters and processes, which explain these patterns and their temporal dynamics, and to analyse the effects of soil moisture heterogeneity upon carbon and water fluxes.
Using existing semi-empirical algorithms, surface soil moisture maps is calculated from ERS and ASAR C-band SAR data. In addition, ALOS and TerraSAR data will be used as they become available during the project term. Soil moistures derived from these SAR measurements will be validated with ground truth measurements taken during the satellite overpass. In addition vertical soil moisture profiles will be measured with TDR profiling probes at different sampling locations along two transects. Continuous soil moisture measurements are provided by four automatic soil moisture stations in three depth (5 cm, 30 cm, 90 cm). These soil moisture measurements will be extended by soil moisture measurements of the project partners as well as soil respiration measurements. Based upon these measurements and the remotely sensed surface soil moisture, the moisture patterns will be analysed to identify the dominant processes and landscape properties explaining these patterns, and to analyse the impact of soil moisture patterns upon soil respiration. This knowledge is crucial to understand the impact of surface heterogeneity upon matter and energy exchange with the atmosphere as well as to understand scaling properties from the locally measurable parameters to regional relevant parameters and fluxes.

The PROcess-oriented Modular EnvironmenT and Vegetation model (PROMET-V) as well as the Biosphere - Energy - Transfer Hydrology (BETHY) scheme will be used. PROMET-V will be applied to investigate the interactions between soil moisture, plant growth, soil respiration and water fluxes with 30 - 100 m spatial resolution on the scale of sub-catchments. Several interfaces to assimilate optical remote sensing data have been established for PROMET-V. Based upon this experience, an efficient development and testing of advanced remote sensing assimilation techniques for SAR derived soil moisture is expected. After testing and validating these assimilation techniques with PROMET-V, they will be integrated into BETHY for regional model applications. Using BETHY will allow to investigate effects of soil moisture patterns upon processes modelled by the project partners.

The analysis of impact of soil moisture upon carbon fluxes will be investigated with particular focus on soil respiration. While this research is the main task for the second project phase, we will start with the required measurements and initial evaluations during the first project phase.

 Deutsche Forschungsgemeinschaft (DFG)