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Accueil du site → Doctorat → Allemagne → 2016 → Signals of Weather Extremes in Soil Moisture and Terrestrial Water Storage from Multi-Sensor Earth Observations and Hydrological Modeling

Technische Universität München (2016)

Signals of Weather Extremes in Soil Moisture and Terrestrial Water Storage from Multi-Sensor Earth Observations and Hydrological Modeling

Abelen, Sarah

Titre : Signals of Weather Extremes in Soil Moisture and Terrestrial Water Storage from Multi-Sensor Earth Observations and Hydrological Modeling

Signaturen von Extremwetterereignissen in Bodenfeuchte und terrestrischer Wasserspeicherung aus multisensoralen Erdbeobachtungsdaten und hydrologischer Modellierung

Auteur : Abelen, Sarah

Université de soutenance : Technische Universität München

Grade : Doktor – Ingenieurs 2016

Résumé partiel
Soil moisture and terrestrial water storage (TWS) are of vital importance for water supply and agricultural production, and play a key role in the climate system. In this study interrelations between these two important hydrological parameters are analyzed. The analysis targets a better understanding of the dynamics of TWS, which in prior studies have primarily been related to changes in groundwater and surface water. Another objective is to gain insight about the drivers of soil moisture on global scale, and to find out whether the combined analysis of both parameters creates added value for their application in the field of natural disaster monitoring. The global mapping of soil moisture and TWS is a relatively new field of research because operational satellite products, which provide information on both parameters on large scales, have just emerged in the past 15 years. This study makes use of TWS data from the satellite gravity mission GRACE (Gravity Recovery And Climate Experiment) and two surface soil moisture satellite products, which originate from the active microwave sensor ASCAT (Advanced SCATterometer) and the passive microwave sensor AMSR-E (Advanced Microwave Scanning Radiometer for Earth Observing System). Additionally, global outputs for root zone soil moisture from the WGHM (WaterGAP Global Hydrology Model) and other ancillary data sets as for example for precipitation are integrated into the study. Following a three step approach first the question is posed whether it is at all feasible to relate data sets for soil moisture and TWS because especially GRACE data differ significantly in data structure and processing from the global soil moisture products. In order to achieve comparable formats, all data sets are harmoniously processed. Main steps include the conversion into spherical harmonics, Gauss filtering and the projection of all data onto a 1◦ ×1◦ grid in monthly time intervals. A least-squares filter is additionally applied to the GRACE data. Results show that the main impact of the harmonious processing is homogeneous spatial smoothing of the data in most parts of the world. Exceptions are mainly deserts. In these regions variations in soil moisture are artificially amplified and altered through the conversion into spherical harmonics and spatial leakage from Gauss filtering. Therefore, these areas are excluded from the analyses. Furthermore, regions of low data quality are identified individually for each data set via correlation and time shift analysis. The information on the data quality is also integrated in the analysis
In summary this study showed that soil moisture and TWS are interrelated over large parts of the world, either because soil moisture contributes significantly to seasonal changes in TWS or because soil moisture changes proportionally with other dominant storage components. In the La Plata Basin this information could be used for the analysis of extreme weather events and associated natural disasters, which had a high impact on society. By the integration of additional information on the absolute amount of soil moisture in the entire root zone, future studies could investigate the concrete share of soil moisture in TW

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Page publiée le 26 septembre 2017